/*
* @(#)File.java 1.122 04/05/05
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.io;
import java.net.URI;
import java.net.URL;
import java.net.MalformedURLException;
import java.net.URISyntaxException;
import java.util.ArrayList;
import java.util.Map;
import java.util.Hashtable;
import java.util.Random;
import java.security.AccessController;
import java.security.AccessControlException;
import sun.security.action.GetPropertyAction;
/**
* An abstract representation of file and directory pathnames.
*
* <p> User interfaces and operating systems use system-dependent <em>pathname
* strings</em> to name files and directories. This class presents an
* abstract, system-independent view of hierarchical pathnames. An
* <em>abstract pathname</em> has two components:
*
* <ol>
* <li> An optional system-dependent <em>prefix</em> string,
* such as a disk-drive specifier, <code>"/"</code> for the UNIX root
* directory, or <code>"\\\\"</code> for a Microsoft Windows UNC pathname, and
* <li> A sequence of zero or more string <em>names</em>.
* </ol>
*
* Each name in an abstract pathname except for the last denotes a directory;
* the last name may denote either a directory or a file. The <em>empty</em>
* abstract pathname has no prefix and an empty name sequence.
*
* <p> The conversion of a pathname string to or from an abstract pathname is
* inherently system-dependent. When an abstract pathname is converted into a
* pathname string, each name is separated from the next by a single copy of
* the default <em>separator character</em>. The default name-separator
* character is defined by the system property <code>file.separator</code>, and
* is made available in the public static fields <code>{@link
* #separator}</code> and <code>{@link #separatorChar}</code> of this class.
* When a pathname string is converted into an abstract pathname, the names
* within it may be separated by the default name-separator character or by any
* other name-separator character that is supported by the underlying system.
*
* <p> A pathname, whether abstract or in string form, may be either
* <em>absolute</em> or <em>relative</em>. An absolute pathname is complete in
* that no other information is required in order to locate the file that it
* denotes. A relative pathname, in contrast, must be interpreted in terms of
* information taken from some other pathname. By default the classes in the
* <code>java.io</code> package always resolve relative pathnames against the
* current user directory. This directory is named by the system property
* <code>user.dir</code>, and is typically the directory in which the Java
* virtual machine was invoked.
*
* <p> The prefix concept is used to handle root directories on UNIX platforms,
* and drive specifiers, root directories and UNC pathnames on Microsoft Windows platforms,
* as follows:
*
* <ul>
*
* <li> For UNIX platforms, the prefix of an absolute pathname is always
* <code>"/"</code>. Relative pathnames have no prefix. The abstract pathname
* denoting the root directory has the prefix <code>"/"</code> and an empty
* name sequence.
*
* <li> For Microsoft Windows platforms, the prefix of a pathname that contains a drive
* specifier consists of the drive letter followed by <code>":"</code> and
* possibly followed by <code>"\\"</code> if the pathname is absolute. The
* prefix of a UNC pathname is <code>"\\\\"</code>; the hostname and the share
* name are the first two names in the name sequence. A relative pathname that
* does not specify a drive has no prefix.
*
* </ul>
*
* <p> Instances of the <code>File</code> class are immutable; that is, once
* created, the abstract pathname represented by a <code>File</code> object
* will never change.
*
* @version 1.122, 05/05/04
* @author unascribed
* @since JDK1.0
*/
public class File
implements Serializable, Comparable<File>
{
/**
* The FileSystem object representing the platform's local file system.
*/
static private FileSystem fs = FileSystem.getFileSystem();
/**
* This abstract pathname's normalized pathname string. A normalized
* pathname string uses the default name-separator character and does not
* contain any duplicate or redundant separators.
*
* @serial
*/
private String path;
/**
* The length of this abstract pathname's prefix, or zero if it has no
* prefix.
*/
private transient int prefixLength;
/**
* Returns the length of this abstract pathname's prefix.
* For use by FileSystem classes.
*/
int getPrefixLength() {
return prefixLength;
}
/**
* The system-dependent default name-separator character. This field is
* initialized to contain the first character of the value of the system
* property <code>file.separator</code>. On UNIX systems the value of this
* field is <code>'/'</code>; on Microsoft Windows systems it is <code>'\\'</code>.
*
* @see java.lang.System#getProperty(java.lang.String)
*/
public static final char separatorChar = fs.getSeparator();
/**
* The system-dependent default name-separator character, represented as a
* string for convenience. This string contains a single character, namely
* <code>{@link #separatorChar}</code>.
*/
public static final String separator = "" + separatorChar;
/**
* The system-dependent path-separator character. This field is
* initialized to contain the first character of the value of the system
* property <code>path.separator</code>. This character is used to
* separate filenames in a sequence of files given as a <em>path list</em>.
* On UNIX systems, this character is <code>':'</code>; on Microsoft Windows systems it
* is <code>';'</code>.
*
* @see java.lang.System#getProperty(java.lang.String)
*/
public static final char pathSeparatorChar = fs.getPathSeparator();
/**
* The system-dependent path-separator character, represented as a string
* for convenience. This string contains a single character, namely
* <code>{@link #pathSeparatorChar}</code>.
*/
public static final String pathSeparator = "" + pathSeparatorChar;
/* -- Constructors -- */
/**
* Internal constructor for already-normalized pathname strings.
*/
private File(String pathname, int prefixLength) {
this.path = pathname;
this.prefixLength = prefixLength;
}
/**
* Internal constructor for already-normalized pathname strings.
* The parameter order is used to disambiguate this method from the
* public(File, String) constructor.
*/
private File(String child, File parent) {
assert parent.path != null;
assert (!parent.path.equals(""));
this.path = fs.resolve(parent.path, child);
this.prefixLength = parent.prefixLength;
}
/**
* Creates a new <code>File</code> instance by converting the given
* pathname string into an abstract pathname. If the given string is
* the empty string, then the result is the empty abstract pathname.
*
* @param pathname A pathname string
* @throws NullPointerException
* If the <code>pathname</code> argument is <code>null</code>
*/
public File(String pathname) {
if (pathname == null) {
throw new NullPointerException();
}
this.path = fs.normalize(pathname);
this.prefixLength = fs.prefixLength(this.path);
}
/* Note: The two-argument File constructors do not interpret an empty
parent abstract pathname as the current user directory. An empty parent
instead causes the child to be resolved against the system-dependent
directory defined by the FileSystem.getDefaultParent method. On Unix
this default is "/", while on Microsoft Windows it is "\\". This is required for
compatibility with the original behavior of this class. */
/**
* Creates a new <code>File</code> instance from a parent pathname string
* and a child pathname string.
*
* <p> If <code>parent</code> is <code>null</code> then the new
* <code>File</code> instance is created as if by invoking the
* single-argument <code>File</code> constructor on the given
* <code>child</code> pathname string.
*
* <p> Otherwise the <code>parent</code> pathname string is taken to denote
* a directory, and the <code>child</code> pathname string is taken to
* denote either a directory or a file. If the <code>child</code> pathname
* string is absolute then it is converted into a relative pathname in a
* system-dependent way. If <code>parent</code> is the empty string then
* the new <code>File</code> instance is created by converting
* <code>child</code> into an abstract pathname and resolving the result
* against a system-dependent default directory. Otherwise each pathname
* string is converted into an abstract pathname and the child abstract
* pathname is resolved against the parent.
*
* @param parent The parent pathname string
* @param child The child pathname string
* @throws NullPointerException
* If <code>child</code> is <code>null</code>
*/
public File(String parent, String child) {
if (child == null) {
throw new NullPointerException();
}
if (parent != null) {
if (parent.equals("")) {
this.path = fs.resolve(fs.getDefaultParent(),
fs.normalize(child));
} else {
this.path = fs.resolve(fs.normalize(parent),
fs.normalize(child));
}
} else {
this.path = fs.normalize(child);
}
this.prefixLength = fs.prefixLength(this.path);
}
/**
* Creates a new <code>File</code> instance from a parent abstract
* pathname and a child pathname string.
*
* <p> If <code>parent</code> is <code>null</code> then the new
* <code>File</code> instance is created as if by invoking the
* single-argument <code>File</code> constructor on the given
* <code>child</code> pathname string.
*
* <p> Otherwise the <code>parent</code> abstract pathname is taken to
* denote a directory, and the <code>child</code> pathname string is taken
* to denote either a directory or a file. If the <code>child</code>
* pathname string is absolute then it is converted into a relative
* pathname in a system-dependent way. If <code>parent</code> is the empty
* abstract pathname then the new <code>File</code> instance is created by
* converting <code>child</code> into an abstract pathname and resolving
* the result against a system-dependent default directory. Otherwise each
* pathname string is converted into an abstract pathname and the child
* abstract pathname is resolved against the parent.
*
* @param parent The parent abstract pathname
* @param child The child pathname string
* @throws NullPointerException
* If <code>child</code> is <code>null</code>
*/
public File(File parent, String child) {
if (child == null) {
throw new NullPointerException();
}
if (parent != null) {
if (parent.path.equals("")) {
this.path = fs.resolve(fs.getDefaultParent(),
fs.normalize(child));
} else {
this.path = fs.resolve(parent.path,
fs.normalize(child));
}
} else {
this.path = fs.normalize(child);
}
this.prefixLength = fs.prefixLength(this.path);
}
/**
* Creates a new <tt>File</tt> instance by converting the given
* <tt>file:</tt> URI into an abstract pathname.
*
* <p> The exact form of a <tt>file:</tt> URI is system-dependent, hence
* the transformation performed by this constructor is also
* system-dependent.
*
* <p> For a given abstract pathname <i>f</i> it is guaranteed that
*
* <blockquote><tt>
* new File(</tt><i> f</i><tt>.{@link #toURI() toURI}()).equals(</tt><i> f</i><tt>.{@link #getAbsoluteFile() getAbsoluteFile}())
* </tt></blockquote>
*
* so long as the original abstract pathname, the URI, and the new abstract
* pathname are all created in (possibly different invocations of) the same
* Java virtual machine. This relationship typically does not hold,
* however, when a <tt>file:</tt> URI that is created in a virtual machine
* on one operating system is converted into an abstract pathname in a
* virtual machine on a different operating system.
*
* @param uri
* An absolute, hierarchical URI with a scheme equal to
* <tt>"file"</tt>, a non-empty path component, and undefined
* authority, query, and fragment components
*
* @throws NullPointerException
* If <tt>uri</tt> is <tt>null</tt>
*
* @throws IllegalArgumentException
* If the preconditions on the parameter do not hold
*
* @see #toURI()
* @see java.net.URI
* @since 1.4
*/
public File(URI uri) {
// Check our many preconditions
if (!uri.isAbsolute())
throw new IllegalArgumentException("URI is not absolute");
if (uri.isOpaque())
throw new IllegalArgumentException("URI is not hierarchical");
String scheme = uri.getScheme();
if ((scheme == null) || !scheme.equalsIgnoreCase("file"))
throw new IllegalArgumentException("URI scheme is not \"file\"");
if (uri.getAuthority() != null)
throw new IllegalArgumentException("URI has an authority component");
if (uri.getFragment() != null)
throw new IllegalArgumentException("URI has a fragment component");
if (uri.getQuery() != null)
throw new IllegalArgumentException("URI has a query component");
String p = uri.getPath();
if (p.equals(""))
throw new IllegalArgumentException("URI path component is empty");
// Okay, now initialize
p = fs.fromURIPath(p);
if (File.separatorChar != '/')
p = p.replace('/', File.separatorChar);
this.path = fs.normalize(p);
this.prefixLength = fs.prefixLength(this.path);
}
/* -- Path-component accessors -- */
/**
* Returns the name of the file or directory denoted by this abstract
* pathname. This is just the last name in the pathname's name
* sequence. If the pathname's name sequence is empty, then the empty
* string is returned.
*
* @return The name of the file or directory denoted by this abstract
* pathname, or the empty string if this pathname's name sequence
* is empty
*/
public String getName() {
int index = path.lastIndexOf(separatorChar);
if (index < prefixLength) return path.substring(prefixLength);
return path.substring(index + 1);
}
/**
* Returns the pathname string of this abstract pathname's parent, or
* <code>null</code> if this pathname does not name a parent directory.
*
* <p> The <em>parent</em> of an abstract pathname consists of the
* pathname's prefix, if any, and each name in the pathname's name
* sequence except for the last. If the name sequence is empty then
* the pathname does not name a parent directory.
*
* @return The pathname string of the parent directory named by this
* abstract pathname, or <code>null</code> if this pathname
* does not name a parent
*/
public String getParent() {
int index = path.lastIndexOf(separatorChar);
if (index < prefixLength) {
if ((prefixLength > 0) && (path.length() > prefixLength))
return path.substring(0, prefixLength);
return null;
}
return path.substring(0, index);
}
/**
* Returns the abstract pathname of this abstract pathname's parent,
* or <code>null</code> if this pathname does not name a parent
* directory.
*
* <p> The <em>parent</em> of an abstract pathname consists of the
* pathname's prefix, if any, and each name in the pathname's name
* sequence except for the last. If the name sequence is empty then
* the pathname does not name a parent directory.
*
* @return The abstract pathname of the parent directory named by this
* abstract pathname, or <code>null</code> if this pathname
* does not name a parent
*
* @since 1.2
*/
public File getParentFile() {
String p = this.getParent();
if (p == null) return null;
return new File(p, this.prefixLength);
}
/**
* Converts this abstract pathname into a pathname string. The resulting
* string uses the {@link #separator default name-separator character} to
* separate the names in the name sequence.
*
* @return The string form of this abstract pathname
*/
public String getPath() {
return path;
}
/* -- Path operations -- */
/**
* Tests whether this abstract pathname is absolute. The definition of
* absolute pathname is system dependent. On UNIX systems, a pathname is
* absolute if its prefix is <code>"/"</code>. On Microsoft Windows systems, a
* pathname is absolute if its prefix is a drive specifier followed by
* <code>"\\"</code>, or if its prefix is <code>"\\\\"</code>.
*
* @return <code>true</code> if this abstract pathname is absolute,
* <code>false</code> otherwise
*/
public boolean isAbsolute() {
return fs.isAbsolute(this);
}
/**
* Returns the absolute pathname string of this abstract pathname.
*
* <p> If this abstract pathname is already absolute, then the pathname
* string is simply returned as if by the <code>{@link #getPath}</code>
* method. If this abstract pathname is the empty abstract pathname then
* the pathname string of the current user directory, which is named by the
* system property <code>user.dir</code>, is returned. Otherwise this
* pathname is resolved in a system-dependent way. On UNIX systems, a
* relative pathname is made absolute by resolving it against the current
* user directory. On Microsoft Windows systems, a relative pathname is made absolute
* by resolving it against the current directory of the drive named by the
* pathname, if any; if not, it is resolved against the current user
* directory.
*
* @return The absolute pathname string denoting the same file or
* directory as this abstract pathname
*
* @throws SecurityException
* If a required system property value cannot be accessed.
*
* @see java.io.File#isAbsolute()
*/
public String getAbsolutePath() {
return fs.resolve(this);
}
/**
* Returns the absolute form of this abstract pathname. Equivalent to
* <code>new File(this.{@link #getAbsolutePath}())</code>.
*
* @return The absolute abstract pathname denoting the same file or
* directory as this abstract pathname
*
* @throws SecurityException
* If a required system property value cannot be accessed.
*
* @since 1.2
*/
public File getAbsoluteFile() {
String absPath = getAbsolutePath();
return new File(absPath, fs.prefixLength(absPath));
}
/**
* Returns the canonical pathname string of this abstract pathname.
*
* <p> A canonical pathname is both absolute and unique. The precise
* definition of canonical form is system-dependent. This method first
* converts this pathname to absolute form if necessary, as if by invoking the
* {@link #getAbsolutePath} method, and then maps it to its unique form in a
* system-dependent way. This typically involves removing redundant names
* such as <tt>"."</tt> and <tt>".."</tt> from the pathname, resolving
* symbolic links (on UNIX platforms), and converting drive letters to a
* standard case (on Microsoft Windows platforms).
*
* <p> Every pathname that denotes an existing file or directory has a
* unique canonical form. Every pathname that denotes a nonexistent file
* or directory also has a unique canonical form. The canonical form of
* the pathname of a nonexistent file or directory may be different from
* the canonical form of the same pathname after the file or directory is
* created. Similarly, the canonical form of the pathname of an existing
* file or directory may be different from the canonical form of the same
* pathname after the file or directory is deleted.
*
* @return The canonical pathname string denoting the same file or
* directory as this abstract pathname
*
* @throws IOException
* If an I/O error occurs, which is possible because the
* construction of the canonical pathname may require
* filesystem queries
*
* @throws SecurityException
* If a required system property value cannot be accessed, or
* if a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkRead}</code> method denies
* read access to the file
*
* @since JDK1.1
*/
public String getCanonicalPath() throws IOException {
return fs.canonicalize(fs.resolve(this));
}
/**
* Returns the canonical form of this abstract pathname. Equivalent to
* <code>new File(this.{@link #getCanonicalPath}())</code>.
*
* @return The canonical pathname string denoting the same file or
* directory as this abstract pathname
*
* @throws IOException
* If an I/O error occurs, which is possible because the
* construction of the canonical pathname may require
* filesystem queries
*
* @throws SecurityException
* If a required system property value cannot be accessed, or
* if a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkRead}</code> method denies
* read access to the file
*
* @since 1.2
*/
public File getCanonicalFile() throws IOException {
String canonPath = getCanonicalPath();
return new File(canonPath, fs.prefixLength(canonPath));
}
private static String slashify(String path, boolean isDirectory) {
String p = path;
if (File.separatorChar != '/')
p = p.replace(File.separatorChar, '/');
if (!p.startsWith("/"))
p = "/" + p;
if (!p.endsWith("/") && isDirectory)
p = p + "/";
return p;
}
/**
* Converts this abstract pathname into a <code>file:</code> URL. The
* exact form of the URL is system-dependent. If it can be determined that
* the file denoted by this abstract pathname is a directory, then the
* resulting URL will end with a slash.
*
* <p> <b>Usage note:</b> This method does not automatically escape
* characters that are illegal in URLs. It is recommended that new code
* convert an abstract pathname into a URL by first converting it into a
* URI, via the {@link #toURI() toURI} method, and then converting the URI
* into a URL via the {@link java.net.URI#toURL() URI.toURL} method.
*
* @return A URL object representing the equivalent file URL
*
* @throws MalformedURLException
* If the path cannot be parsed as a URL
*
* @see #toURI()
* @see java.net.URI
* @see java.net.URI#toURL()
* @see java.net.URL
* @since 1.2
*/
public URL toURL() throws MalformedURLException {
return new URL("file", "", slashify(getAbsolutePath(), isDirectory()));
}
/**
* Constructs a <tt>file:</tt> URI that represents this abstract pathname.
*
* <p> The exact form of the URI is system-dependent. If it can be
* determined that the file denoted by this abstract pathname is a
* directory, then the resulting URI will end with a slash.
*
* <p> For a given abstract pathname <i>f</i>, it is guaranteed that
*
* <blockquote><tt>
* new {@link #File(java.net.URI) File}(</tt><i> f</i><tt>.toURI()).equals(</tt><i> f</i><tt>.{@link #getAbsoluteFile() getAbsoluteFile}())
* </tt></blockquote>
*
* so long as the original abstract pathname, the URI, and the new abstract
* pathname are all created in (possibly different invocations of) the same
* Java virtual machine. Due to the system-dependent nature of abstract
* pathnames, however, this relationship typically does not hold when a
* <tt>file:</tt> URI that is created in a virtual machine on one operating
* system is converted into an abstract pathname in a virtual machine on a
* different operating system.
*
* @return An absolute, hierarchical URI with a scheme equal to
* <tt>"file"</tt>, a path representing this abstract pathname,
* and undefined authority, query, and fragment components
*
* @see #File(java.net.URI)
* @see java.net.URI
* @see java.net.URI#toURL()
* @since 1.4
*/
public URI toURI() {
try {
File f = getAbsoluteFile();
String sp = slashify(f.getPath(), f.isDirectory());
if (sp.startsWith("//"))
sp = "//" + sp;
return new URI("file", null, sp, null);
} catch (URISyntaxException x) {
throw new Error(x); // Can't happen
}
}
/* -- Attribute accessors -- */
/**
* Tests whether the application can read the file denoted by this
* abstract pathname.
*
* @return <code>true</code> if and only if the file specified by this
* abstract pathname exists <em>and</em> can be read by the
* application; <code>false</code> otherwise
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkRead(java.lang.String)}</code>
* method denies read access to the file
*/
public boolean canRead() {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkRead(path);
}
return fs.checkAccess(this, false);
}
/**
* Tests whether the application can modify the file denoted by this
* abstract pathname.
*
* @return <code>true</code> if and only if the file system actually
* contains a file denoted by this abstract pathname <em>and</em>
* the application is allowed to write to the file;
* <code>false</code> otherwise.
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
* method denies write access to the file
*/
public boolean canWrite() {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkWrite(path);
}
return fs.checkAccess(this, true);
}
/**
* Tests whether the file or directory denoted by this abstract pathname
* exists.
*
* @return <code>true</code> if and only if the file or directory denoted
* by this abstract pathname exists; <code>false</code> otherwise
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkRead(java.lang.String)}</code>
* method denies read access to the file or directory
*/
public boolean exists() {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkRead(path);
}
return ((fs.getBooleanAttributes(this) & FileSystem.BA_EXISTS) != 0);
}
/**
* Tests whether the file denoted by this abstract pathname is a
* directory.
*
* @return <code>true</code> if and only if the file denoted by this
* abstract pathname exists <em>and</em> is a directory;
* <code>false</code> otherwise
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkRead(java.lang.String)}</code>
* method denies read access to the file
*/
public boolean isDirectory() {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkRead(path);
}
return ((fs.getBooleanAttributes(this) & FileSystem.BA_DIRECTORY)
!= 0);
}
/**
* Tests whether the file denoted by this abstract pathname is a normal
* file. A file is <em>normal</em> if it is not a directory and, in
* addition, satisfies other system-dependent criteria. Any non-directory
* file created by a Java application is guaranteed to be a normal file.
*
* @return <code>true</code> if and only if the file denoted by this
* abstract pathname exists <em>and</em> is a normal file;
* <code>false</code> otherwise
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkRead(java.lang.String)}</code>
* method denies read access to the file
*/
public boolean isFile() {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkRead(path);
}
return ((fs.getBooleanAttributes(this) & FileSystem.BA_REGULAR) != 0);
}
/**
* Tests whether the file named by this abstract pathname is a hidden
* file. The exact definition of <em>hidden</em> is system-dependent. On
* UNIX systems, a file is considered to be hidden if its name begins with
* a period character (<code>'.'</code>). On Microsoft Windows systems, a file is
* considered to be hidden if it has been marked as such in the filesystem.
*
* @return <code>true</code> if and only if the file denoted by this
* abstract pathname is hidden according to the conventions of the
* underlying platform
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkRead(java.lang.String)}</code>
* method denies read access to the file
*
* @since 1.2
*/
public boolean isHidden() {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkRead(path);
}
return ((fs.getBooleanAttributes(this) & FileSystem.BA_HIDDEN) != 0);
}
/**
* Returns the time that the file denoted by this abstract pathname was
* last modified.
*
* @return A <code>long</code> value representing the time the file was
* last modified, measured in milliseconds since the epoch
* (00:00:00 GMT, January 1, 1970), or <code>0L</code> if the
* file does not exist or if an I/O error occurs
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkRead(java.lang.String)}</code>
* method denies read access to the file
*/
public long lastModified() {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkRead(path);
}
return fs.getLastModifiedTime(this);
}
/**
* Returns the length of the file denoted by this abstract pathname.
* The return value is unspecified if this pathname denotes a directory.
*
* @return The length, in bytes, of the file denoted by this abstract
* pathname, or <code>0L</code> if the file does not exist
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkRead(java.lang.String)}</code>
* method denies read access to the file
*/
public long length() {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkRead(path);
}
return fs.getLength(this);
}
/* -- File operations -- */
/**
* Atomically creates a new, empty file named by this abstract pathname if
* and only if a file with this name does not yet exist. The check for the
* existence of the file and the creation of the file if it does not exist
* are a single operation that is atomic with respect to all other
* filesystem activities that might affect the file.
* <P>
* Note: this method should <i>not</i> be used for file-locking, as
* the resulting protocol cannot be made to work reliably. The
* {@link java.nio.channels.FileLock FileLock}
* facility should be used instead.
*
* @return <code>true</code> if the named file does not exist and was
* successfully created; <code>false</code> if the named file
* already exists
*
* @throws IOException
* If an I/O error occurred
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
* method denies write access to the file
*
* @since 1.2
*/
public boolean createNewFile() throws IOException {
SecurityManager security = System.getSecurityManager();
if (security != null) security.checkWrite(path);
return fs.createFileExclusively(path);
}
/**
* Deletes the file or directory denoted by this abstract pathname. If
* this pathname denotes a directory, then the directory must be empty in
* order to be deleted.
*
* @return <code>true</code> if and only if the file or directory is
* successfully deleted; <code>false</code> otherwise
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkDelete}</code> method denies
* delete access to the file
*/
public boolean delete() {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkDelete(path);
}
return fs.delete(this);
}
/**
* Requests that the file or directory denoted by this abstract
* pathname be deleted when the virtual machine terminates.
* Deletion will be attempted only for normal termination of the
* virtual machine, as defined by the Java Language Specification.
*
* <p> Once deletion has been requested, it is not possible to cancel the
* request. This method should therefore be used with care.
*
* <P>
* Note: this method should <i>not</i> be used for file-locking, as
* the resulting protocol cannot be made to work reliably. The
* {@link java.nio.channels.FileLock FileLock}
* facility should be used instead.
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkDelete}</code> method denies
* delete access to the file
*
* @see #delete
*
* @since 1.2
*/
public void deleteOnExit() {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkDelete(path);
}
fs.deleteOnExit(this);
}
/**
* Returns an array of strings naming the files and directories in the
* directory denoted by this abstract pathname.
*
* <p> If this abstract pathname does not denote a directory, then this
* method returns <code>null</code>. Otherwise an array of strings is
* returned, one for each file or directory in the directory. Names
* denoting the directory itself and the directory's parent directory are
* not included in the result. Each string is a file name rather than a
* complete path.
*
* <p> There is no guarantee that the name strings in the resulting array
* will appear in any specific order; they are not, in particular,
* guaranteed to appear in alphabetical order.
*
* @return An array of strings naming the files and directories in the
* directory denoted by this abstract pathname. The array will be
* empty if the directory is empty. Returns <code>null</code> if
* this abstract pathname does not denote a directory, or if an
* I/O error occurs.
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkRead(java.lang.String)}</code>
* method denies read access to the directory
*/
public String[] list() {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkRead(path);
}
return fs.list(this);
}
/**
* Returns an array of strings naming the files and directories in the
* directory denoted by this abstract pathname that satisfy the specified
* filter. The behavior of this method is the same as that of the
* <code>{@link #list()}</code> method, except that the strings in the
* returned array must satisfy the filter. If the given
* <code>filter</code> is <code>null</code> then all names are accepted.
* Otherwise, a name satisfies the filter if and only if the value
* <code>true</code> results when the <code>{@link
* FilenameFilter#accept}</code> method of the filter is invoked on this
* abstract pathname and the name of a file or directory in the directory
* that it denotes.
*
* @param filter A filename filter
*
* @return An array of strings naming the files and directories in the
* directory denoted by this abstract pathname that were accepted
* by the given <code>filter</code>. The array will be empty if
* the directory is empty or if no names were accepted by the
* filter. Returns <code>null</code> if this abstract pathname
* does not denote a directory, or if an I/O error occurs.
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkRead(java.lang.String)}</code>
* method denies read access to the directory
*/
public String[] list(FilenameFilter filter) {
String names[] = list();
if ((names == null) || (filter == null)) {
return names;
}
ArrayList v = new ArrayList();
for (int i = 0 ; i < names.length ; i++) {
if (filter.accept(this, names[i])) {
v.add(names[i]);
}
}
return (String[])(v.toArray(new String[0]));
}
/**
* Returns an array of abstract pathnames denoting the files in the
* directory denoted by this abstract pathname.
*
* <p> If this abstract pathname does not denote a directory, then this
* method returns <code>null</code>. Otherwise an array of
* <code>File</code> objects is returned, one for each file or directory in
* the directory. Pathnames denoting the directory itself and the
* directory's parent directory are not included in the result. Each
* resulting abstract pathname is constructed from this abstract pathname
* using the <code>{@link #File(java.io.File, java.lang.String)
* File(File, String)}</code> constructor. Therefore if this pathname
* is absolute then each resulting pathname is absolute; if this pathname
* is relative then each resulting pathname will be relative to the same
* directory.
*
* <p> There is no guarantee that the name strings in the resulting array
* will appear in any specific order; they are not, in particular,
* guaranteed to appear in alphabetical order.
*
* @return An array of abstract pathnames denoting the files and
* directories in the directory denoted by this abstract
* pathname. The array will be empty if the directory is
* empty. Returns <code>null</code> if this abstract pathname
* does not denote a directory, or if an I/O error occurs.
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkRead(java.lang.String)}</code>
* method denies read access to the directory
*
* @since 1.2
*/
public File[] listFiles() {
String[] ss = list();
if (ss == null) return null;
int n = ss.length;
File[] fs = new File[n];
for (int i = 0; i < n; i++) {
fs[i] = new File(ss[i], this);
}
return fs;
}
/**
* Returns an array of abstract pathnames denoting the files and
* directories in the directory denoted by this abstract pathname that
* satisfy the specified filter. The behavior of this method is the
* same as that of the <code>{@link #listFiles()}</code> method, except
* that the pathnames in the returned array must satisfy the filter.
* If the given <code>filter</code> is <code>null</code> then all
* pathnames are accepted. Otherwise, a pathname satisfies the filter
* if and only if the value <code>true</code> results when the
* <code>{@link FilenameFilter#accept}</code> method of the filter is
* invoked on this abstract pathname and the name of a file or
* directory in the directory that it denotes.
*
* @param filter A filename filter
*
* @return An array of abstract pathnames denoting the files and
* directories in the directory denoted by this abstract
* pathname. The array will be empty if the directory is
* empty. Returns <code>null</code> if this abstract pathname
* does not denote a directory, or if an I/O error occurs.
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkRead(java.lang.String)}</code>
* method denies read access to the directory
*
* @since 1.2
*/
public File[] listFiles(FilenameFilter filter) {
String ss[] = list();
if (ss == null) return null;
ArrayList v = new ArrayList();
for (int i = 0 ; i < ss.length ; i++) {
if ((filter == null) || filter.accept(this, ss[i])) {
v.add(new File(ss[i], this));
}
}
return (File[])(v.toArray(new File[0]));
}
/**
* Returns an array of abstract pathnames denoting the files and
* directories in the directory denoted by this abstract pathname that
* satisfy the specified filter. The behavior of this method is the
* same as that of the <code>{@link #listFiles()}</code> method, except
* that the pathnames in the returned array must satisfy the filter.
* If the given <code>filter</code> is <code>null</code> then all
* pathnames are accepted. Otherwise, a pathname satisfies the filter
* if and only if the value <code>true</code> results when the
* <code>{@link FileFilter#accept(java.io.File)}</code> method of
* the filter is invoked on the pathname.
*
* @param filter A file filter
*
* @return An array of abstract pathnames denoting the files and
* directories in the directory denoted by this abstract
* pathname. The array will be empty if the directory is
* empty. Returns <code>null</code> if this abstract pathname
* does not denote a directory, or if an I/O error occurs.
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkRead(java.lang.String)}</code>
* method denies read access to the directory
*
* @since 1.2
*/
public File[] listFiles(FileFilter filter) {
String ss[] = list();
if (ss == null) return null;
ArrayList v = new ArrayList();
for (int i = 0 ; i < ss.length ; i++) {
File f = new File(ss[i], this);
if ((filter == null) || filter.accept(f)) {
v.add(f);
}
}
return (File[])(v.toArray(new File[0]));
}
/**
* Creates the directory named by this abstract pathname.
*
* @return <code>true</code> if and only if the directory was
* created; <code>false</code> otherwise
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
* method does not permit the named directory to be created
*/
public boolean mkdir() {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkWrite(path);
}
return fs.createDirectory(this);
}
/**
* Creates the directory named by this abstract pathname, including any
* necessary but nonexistent parent directories. Note that if this
* operation fails it may have succeeded in creating some of the necessary
* parent directories.
*
* @return <code>true</code> if and only if the directory was created,
* along with all necessary parent directories; <code>false</code>
* otherwise
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkRead(java.lang.String)}</code>
* method does not permit verification of the existence of the
* named directory and all necessary parent directories; or if
* the <code>{@link
* java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
* method does not permit the named directory and all necessary
* parent directories to be created
*/
public boolean mkdirs() {
if (exists()) {
return false;
}
if (mkdir()) {
return true;
}
File canonFile = null;
try {
canonFile = getCanonicalFile();
} catch (IOException e) {
return false;
}
String parent = canonFile.getParent();
return (parent != null) &&
(new File(parent, fs.prefixLength(parent)).mkdirs() &&
canonFile.mkdir());
}
/**
* Renames the file denoted by this abstract pathname.
*
* <p> Many aspects of the behavior of this method are inherently
* platform-dependent: The rename operation might not be able to move a
* file from one filesystem to another, it might not be atomic, and it
* might not succeed if a file with the destination abstract pathname
* already exists. The return value should always be checked to make sure
* that the rename operation was successful.
*
* @param dest The new abstract pathname for the named file
*
* @return <code>true</code> if and only if the renaming succeeded;
* <code>false</code> otherwise
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
* method denies write access to either the old or new pathnames
*
* @throws NullPointerException
* If parameter <code>dest</code> is <code>null</code>
*/
public boolean renameTo(File dest) {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkWrite(path);
security.checkWrite(dest.path);
}
return fs.rename(this, dest);
}
/**
* Sets the last-modified time of the file or directory named by this
* abstract pathname.
*
* <p> All platforms support file-modification times to the nearest second,
* but some provide more precision. The argument will be truncated to fit
* the supported precision. If the operation succeeds and no intervening
* operations on the file take place, then the next invocation of the
* <code>{@link #lastModified}</code> method will return the (possibly
* truncated) <code>time</code> argument that was passed to this method.
*
* @param time The new last-modified time, measured in milliseconds since
* the epoch (00:00:00 GMT, January 1, 1970)
*
* @return <code>true</code> if and only if the operation succeeded;
* <code>false</code> otherwise
*
* @throws IllegalArgumentException If the argument is negative
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
* method denies write access to the named file
*
* @since 1.2
*/
public boolean setLastModified(long time) {
if (time < 0) throw new IllegalArgumentException("Negative time");
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkWrite(path);
}
return fs.setLastModifiedTime(this, time);
}
/**
* Marks the file or directory named by this abstract pathname so that
* only read operations are allowed. After invoking this method the file
* or directory is guaranteed not to change until it is either deleted or
* marked to allow write access. Whether or not a read-only file or
* directory may be deleted depends upon the underlying system.
*
* @return <code>true</code> if and only if the operation succeeded;
* <code>false</code> otherwise
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
* method denies write access to the named file
*
* @since 1.2
*/
public boolean setReadOnly() {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkWrite(path);
}
return fs.setReadOnly(this);
}
/* -- Filesystem interface -- */
/**
* List the available filesystem roots.
*
* <p> A particular Java platform may support zero or more
* hierarchically-organized file systems. Each file system has a
* <code>root</code> directory from which all other files in that file
* system can be reached. Windows platforms, for example, have a root
* directory for each active drive; UNIX platforms have a single root
* directory, namely <code>"/"</code>. The set of available filesystem
* roots is affected by various system-level operations such as the insertion
* or ejection of removable media and the disconnecting or unmounting of
* physical or virtual disk drives.
*
* <p> This method returns an array of <code>File</code> objects that
* denote the root directories of the available filesystem roots. It is
* guaranteed that the canonical pathname of any file physically present on
* the local machine will begin with one of the roots returned by this
* method.
*
* <p> The canonical pathname of a file that resides on some other machine
* and is accessed via a remote-filesystem protocol such as SMB or NFS may
* or may not begin with one of the roots returned by this method. If the
* pathname of a remote file is syntactically indistinguishable from the
* pathname of a local file then it will begin with one of the roots
* returned by this method. Thus, for example, <code>File</code> objects
* denoting the root directories of the mapped network drives of a Windows
* platform will be returned by this method, while <code>File</code>
* objects containing UNC pathnames will not be returned by this method.
*
* <p> Unlike most methods in this class, this method does not throw
* security exceptions. If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkRead(java.lang.String)}</code> method
* denies read access to a particular root directory, then that directory
* will not appear in the result.
*
* @return An array of <code>File</code> objects denoting the available
* filesystem roots, or <code>null</code> if the set of roots
* could not be determined. The array will be empty if there are
* no filesystem roots.
*
* @since 1.2
*/
public static File[] listRoots() {
return fs.listRoots();
}
/* -- Temporary files -- */
private static final Object tmpFileLock = new Object();
private static int counter = -1; /* Protected by tmpFileLock */
private static File generateFile(String prefix, String suffix, File dir)
throws IOException
{
if (counter == -1) {
counter = new Random().nextInt() & 0xffff;
}
counter++;
return new File(dir, prefix + Integer.toString(counter) + suffix);
}
private static String tmpdir; /* Protected by tmpFileLock */
private static String getTempDir() {
if (tmpdir == null) {
GetPropertyAction a = new GetPropertyAction("java.io.tmpdir");
tmpdir = ((String) AccessController.doPrivileged(a));
tmpdir = fs.normalize(tmpdir);
}
return tmpdir;
}
private static boolean checkAndCreate(String filename, SecurityManager sm)
throws IOException
{
if (sm != null) {
try {
sm.checkWrite(filename);
} catch (AccessControlException x) {
/* Throwing the original AccessControlException could disclose
the location of the default temporary directory, so we
re-throw a more innocuous SecurityException */
throw new SecurityException("Unable to create temporary file");
}
}
return fs.createFileExclusively(filename);
}
/**
* <p> Creates a new empty file in the specified directory, using the
* given prefix and suffix strings to generate its name. If this method
* returns successfully then it is guaranteed that:
*
* <ol>
* <li> The file denoted by the returned abstract pathname did not exist
* before this method was invoked, and
* <li> Neither this method nor any of its variants will return the same
* abstract pathname again in the current invocation of the virtual
* machine.
* </ol>
*
* This method provides only part of a temporary-file facility. To arrange
* for a file created by this method to be deleted automatically, use the
* <code>{@link #deleteOnExit}</code> method.
*
* <p> The <code>prefix</code> argument must be at least three characters
* long. It is recommended that the prefix be a short, meaningful string
* such as <code>"hjb"</code> or <code>"mail"</code>. The
* <code>suffix</code> argument may be <code>null</code>, in which case the
* suffix <code>".tmp"</code> will be used.
*
* <p> To create the new file, the prefix and the suffix may first be
* adjusted to fit the limitations of the underlying platform. If the
* prefix is too long then it will be truncated, but its first three
* characters will always be preserved. If the suffix is too long then it
* too will be truncated, but if it begins with a period character
* (<code>'.'</code>) then the period and the first three characters
* following it will always be preserved. Once these adjustments have been
* made the name of the new file will be generated by concatenating the
* prefix, five or more internally-generated characters, and the suffix.
*
* <p> If the <code>directory</code> argument is <code>null</code> then the
* system-dependent default temporary-file directory will be used. The
* default temporary-file directory is specified by the system property
* <code>java.io.tmpdir</code>. On UNIX systems the default value of this
* property is typically <code>"/tmp"</code> or <code>"/var/tmp"</code>; on
* Microsoft Windows systems it is typically <code>"C:\\WINNT\\TEMP"</code>. A different
* value may be given to this system property when the Java virtual machine
* is invoked, but programmatic changes to this property are not guaranteed
* to have any effect upon the temporary directory used by this method.
*
* @param prefix The prefix string to be used in generating the file's
* name; must be at least three characters long
*
* @param suffix The suffix string to be used in generating the file's
* name; may be <code>null</code>, in which case the
* suffix <code>".tmp"</code> will be used
*
* @param directory The directory in which the file is to be created, or
* <code>null</code> if the default temporary-file
* directory is to be used
*
* @return An abstract pathname denoting a newly-created empty file
*
* @throws IllegalArgumentException
* If the <code>prefix</code> argument contains fewer than three
* characters
*
* @throws IOException If a file could not be created
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
* method does not allow a file to be created
*
* @since 1.2
*/
public static File createTempFile(String prefix, String suffix,
File directory)
throws IOException
{
if (prefix == null) throw new NullPointerException();
if (prefix.length() < 3)
throw new IllegalArgumentException("Prefix string too short");
String s = (suffix == null) ? ".tmp" : suffix;
synchronized (tmpFileLock) {
if (directory == null) {
String tmpDir = getTempDir();
directory = new File(tmpDir, fs.prefixLength(tmpDir));
}
SecurityManager sm = System.getSecurityManager();
File f;
do {
f = generateFile(prefix, s, directory);
} while (!checkAndCreate(f.getPath(), sm));
return f;
}
}
/**
* Creates an empty file in the default temporary-file directory, using
* the given prefix and suffix to generate its name. Invoking this method
* is equivalent to invoking <code>{@link #createTempFile(java.lang.String,
* java.lang.String, java.io.File)
* createTempFile(prefix, suffix, null)}</code>.
*
* @param prefix The prefix string to be used in generating the file's
* name; must be at least three characters long
*
* @param suffix The suffix string to be used in generating the file's
* name; may be <code>null</code>, in which case the
* suffix <code>".tmp"</code> will be used
*
* @return An abstract pathname denoting a newly-created empty file
*
* @throws IllegalArgumentException
* If the <code>prefix</code> argument contains fewer than three
* characters
*
* @throws IOException If a file could not be created
*
* @throws SecurityException
* If a security manager exists and its <code>{@link
* java.lang.SecurityManager#checkWrite(java.lang.String)}</code>
* method does not allow a file to be created
*
* @since 1.2
*/
public static File createTempFile(String prefix, String suffix)
throws IOException
{
return createTempFile(prefix, suffix, null);
}
/* -- Basic infrastructure -- */
/**
* Compares two abstract pathnames lexicographically. The ordering
* defined by this method depends upon the underlying system. On UNIX
* systems, alphabetic case is significant in comparing pathnames; on Microsoft Windows
* systems it is not.
*
* @param pathname The abstract pathname to be compared to this abstract
* pathname
*
* @return Zero if the argument is equal to this abstract pathname, a
* value less than zero if this abstract pathname is
* lexicographically less than the argument, or a value greater
* than zero if this abstract pathname is lexicographically
* greater than the argument
*
* @since 1.2
*/
public int compareTo(File pathname) {
return fs.compare(this, pathname);
}
/**
* Tests this abstract pathname for equality with the given object.
* Returns <code>true</code> if and only if the argument is not
* <code>null</code> and is an abstract pathname that denotes the same file
* or directory as this abstract pathname. Whether or not two abstract
* pathnames are equal depends upon the underlying system. On UNIX
* systems, alphabetic case is significant in comparing pathnames; on Microsoft Windows
* systems it is not.
*
* @param obj The object to be compared with this abstract pathname
*
* @return <code>true</code> if and only if the objects are the same;
* <code>false</code> otherwise
*/
public boolean equals(Object obj) {
if ((obj != null) && (obj instanceof File)) {
return compareTo((File)obj) == 0;
}
return false;
}
/**
* Computes a hash code for this abstract pathname. Because equality of
* abstract pathnames is inherently system-dependent, so is the computation
* of their hash codes. On UNIX systems, the hash code of an abstract
* pathname is equal to the exclusive <em>or</em> of the hash code
* of its pathname string and the decimal value
* <code>1234321</code>. On Microsoft Windows systems, the hash
* code is equal to the exclusive <em>or</em> of the hash code of
* its pathname string converted to lower case and the decimal
* value <code>1234321</code>.
*
* @return A hash code for this abstract pathname
*/
public int hashCode() {
return fs.hashCode(this);
}
/**
* Returns the pathname string of this abstract pathname. This is just the
* string returned by the <code>{@link #getPath}</code> method.
*
* @return The string form of this abstract pathname
*/
public String toString() {
return getPath();
}
/**
* WriteObject is called to save this filename.
* The separator character is saved also so it can be replaced
* in case the path is reconstituted on a different host type.
*/
private synchronized void writeObject(java.io.ObjectOutputStream s)
throws IOException
{
s.defaultWriteObject();
s.writeChar(this.separatorChar); // Add the separator character
}
/**
* readObject is called to restore this filename.
* The original separator character is read. If it is different
* than the separator character on this system, then the old separator
* is replaced by the local separator.
*/
private synchronized void readObject(java.io.ObjectInputStream s)
throws IOException, ClassNotFoundException
{
s.defaultReadObject();
char sep = s.readChar(); // read the previous separator char
if (sep != separatorChar)
this.path = this.path.replace(sep, separatorChar);
this.path = fs.normalize(this.path);
this.prefixLength = fs.prefixLength(this.path);
}
/** use serialVersionUID from JDK 1.0.2 for interoperability */
private static final long serialVersionUID = 301077366599181567L;
}