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/*
* @(#)MimeTypeParameterList.java 1.13 07/05/14
*/
package javax.activation;
import java.util.Hashtable;
import java.util.Enumeration;
import java.util.Locale;
/**
* A parameter list of a MimeType
* as defined in RFC 2045 and 2046. The Primary type of the
* object must already be stripped off.
*
* @see javax.activation.MimeType
*/
public class MimeTypeParameterList {
private Hashtable parameters;
/**
* A string that holds all the special chars.
*/
private static final String TSPECIALS = "()<>@,;:/[]?=\\\"";
/**
* Default constructor.
*/
public MimeTypeParameterList() {
parameters = new Hashtable();
}
/**
* Constructs a new MimeTypeParameterList with the passed in data.
*
* @param parameterList an RFC 2045, 2046 compliant parameter list.
*/
public MimeTypeParameterList(String parameterList)
throws MimeTypeParseException {
parameters = new Hashtable();
// now parse rawdata
parse(parameterList);
}
/**
* A routine for parsing the parameter list out of a String.
*
* @param parameterList an RFC 2045, 2046 compliant parameter list.
*/
protected void parse(String parameterList) throws MimeTypeParseException {
if (parameterList == null)
return;
int length = parameterList.length();
if (length <= 0)
return;
int i;
char c;
for (i = skipWhiteSpace(parameterList, 0);
i < length && (c = parameterList.charAt(i)) == ';';
i = skipWhiteSpace(parameterList, i)) {
int lastIndex;
String name;
String value;
// eat the ';'
i++;
// now parse the parameter name
// skip whitespace
i = skipWhiteSpace(parameterList, i);
// tolerate trailing semicolon, even though it violates the spec
if (i >= length)
return;
// find the end of the token char run
lastIndex = i;
while ((i < length) && isTokenChar(parameterList.charAt(i)))
i++;
name = parameterList.substring(lastIndex, i).
toLowerCase(Locale.ENGLISH);
// now parse the '=' that separates the name from the value
i = skipWhiteSpace(parameterList, i);
if (i >= length || parameterList.charAt(i) != '=')
throw new MimeTypeParseException(
"Couldn't find the '=' that separates a " +
"parameter name from its value.");
// eat it and parse the parameter value
i++;
i = skipWhiteSpace(parameterList, i);
if (i >= length)
throw new MimeTypeParseException(
"Couldn't find a value for parameter named " + name);
// now find out whether or not we have a quoted value
c = parameterList.charAt(i);
if (c == '"') {
// yup it's quoted so eat it and capture the quoted string
i++;
if (i >= length)
throw new MimeTypeParseException(
"Encountered unterminated quoted parameter value.");
lastIndex = i;
// find the next unescaped quote
while (i < length) {
c = parameterList.charAt(i);
if (c == '"')
break;
if (c == '\\') {
// found an escape sequence
// so skip this and the
// next character
i++;
}
i++;
}
if (c != '"')
throw new MimeTypeParseException(
"Encountered unterminated quoted parameter value.");
value = unquote(parameterList.substring(lastIndex, i));
// eat the quote
i++;
} else if (isTokenChar(c)) {
// nope it's an ordinary token so it
// ends with a non-token char
lastIndex = i;
while (i < length && isTokenChar(parameterList.charAt(i)))
i++;
value = parameterList.substring(lastIndex, i);
} else {
// it ain't a value
throw new MimeTypeParseException(
"Unexpected character encountered at index " + i);
}
// now put the data into the hashtable
parameters.put(name, value);
}
if (i < length) {
throw new MimeTypeParseException(
"More characters encountered in input than expected.");
}
}
/**
* Return the number of name-value pairs in this list.
*
* @return the number of parameters
*/
public int size() {
return parameters.size();
}
/**
* Determine whether or not this list is empty.
*
* @return true if there are no parameters
*/
public boolean isEmpty() {
return parameters.isEmpty();
}
/**
* Retrieve the value associated with the given name, or null if there
* is no current association.
*
* @param name the parameter name
* @return the parameter's value
*/
public String get(String name) {
return (String)parameters.get(name.trim().toLowerCase(Locale.ENGLISH));
}
/**
* Set the value to be associated with the given name, replacing
* any previous association.
*
* @param name the parameter name
* @param value the parameter's value
*/
public void set(String name, String value) {
parameters.put(name.trim().toLowerCase(Locale.ENGLISH), value);
}
/**
* Remove any value associated with the given name.
*
* @param name the parameter name
*/
public void remove(String name) {
parameters.remove(name.trim().toLowerCase(Locale.ENGLISH));
}
/**
* Retrieve an enumeration of all the names in this list.
*
* @return an enumeration of all parameter names
*/
public Enumeration getNames() {
return parameters.keys();
}
/**
* Return a string representation of this object.
*/
public String toString() {
StringBuffer buffer = new StringBuffer();
buffer.ensureCapacity(parameters.size() * 16);
// heuristic: 8 characters per field
Enumeration keys = parameters.keys();
while (keys.hasMoreElements()) {
String key = (String)keys.nextElement();
buffer.append("; ");
buffer.append(key);
buffer.append('=');
buffer.append(quote((String)parameters.get(key)));
}
return buffer.toString();
}
// below here be scary parsing related things
/**
* Determine whether or not a given character belongs to a legal token.
*/
private static boolean isTokenChar(char c) {
return ((c > 040) && (c < 0177)) && (TSPECIALS.indexOf(c) < 0);
}
/**
* return the index of the first non white space character in
* rawdata at or after index i.
*/
private static int skipWhiteSpace(String rawdata, int i) {
int length = rawdata.length();
while ((i < length) && Character.isWhitespace(rawdata.charAt(i)))
i++;
return i;
}
/**
* A routine that knows how and when to quote and escape the given value.
*/
private static String quote(String value) {
boolean needsQuotes = false;
// check to see if we actually have to quote this thing
int length = value.length();
for (int i = 0; (i < length) && !needsQuotes; i++) {
needsQuotes = !isTokenChar(value.charAt(i));
}
if (needsQuotes) {
StringBuffer buffer = new StringBuffer();
buffer.ensureCapacity((int)(length * 1.5));
// add the initial quote
buffer.append('"');
// add the properly escaped text
for (int i = 0; i < length; ++i) {
char c = value.charAt(i);
if ((c == '\\') || (c == '"'))
buffer.append('\\');
buffer.append(c);
}
// add the closing quote
buffer.append('"');
return buffer.toString();
} else {
return value;
}
}
/**
* A routine that knows how to strip the quotes and
* escape sequences from the given value.
*/
private static String unquote(String value) {
int valueLength = value.length();
StringBuffer buffer = new StringBuffer();
buffer.ensureCapacity(valueLength);
boolean escaped = false;
for (int i = 0; i < valueLength; ++i) {
char currentChar = value.charAt(i);
if (!escaped && (currentChar != '\\')) {
buffer.append(currentChar);
} else if (escaped) {
buffer.append(currentChar);
escaped = false;
} else {
escaped = true;
}
}
return buffer.toString();
}
}