/*
* Copyright 2002-2017 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.core.io;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URI;
import java.net.URL;
import java.net.URLConnection;
import java.nio.channels.ReadableByteChannel;
import org.springframework.util.ResourceUtils;
/**
* Abstract base class for resources which resolve URLs into File references,
* such as {@link UrlResource} or {@link ClassPathResource}.
*
* <p>Detects the "file" protocol as well as the JBoss "vfs" protocol in URLs,
* resolving file system references accordingly.
*
* @author Juergen Hoeller
* @since 3.0
*/
public abstract class AbstractFileResolvingResource extends AbstractResource {
@Override
public boolean isFile() {
try {
URL url = getURL();
if (url.getProtocol().startsWith(ResourceUtils.URL_PROTOCOL_VFS)) {
return VfsResourceDelegate.getResource(url).isFile();
}
return ResourceUtils.URL_PROTOCOL_FILE.equals(url.getProtocol());
}
catch (IOException ex) {
return false;
}
}
/**
* This implementation returns a File reference for the underlying class path
* resource, provided that it refers to a file in the file system.
* @see org.springframework.util.ResourceUtils#getFile(java.net.URL, String)
*/
@Override
public File getFile() throws IOException {
URL url = getURL();
if (url.getProtocol().startsWith(ResourceUtils.URL_PROTOCOL_VFS)) {
return VfsResourceDelegate.getResource(url).getFile();
}
return ResourceUtils.getFile(url, getDescription());
}
/**
* This implementation determines the underlying File
* (or jar file, in case of a resource in a jar/zip).
*/
@Override
protected File getFileForLastModifiedCheck() throws IOException {
URL url = getURL();
if (ResourceUtils.isJarURL(url)) {
URL actualUrl = ResourceUtils.extractArchiveURL(url);
if (actualUrl.getProtocol().startsWith(ResourceUtils.URL_PROTOCOL_VFS)) {
return VfsResourceDelegate.getResource(actualUrl).getFile();
}
return ResourceUtils.getFile(actualUrl, "Jar URL");
}
else {
return getFile();
}
}
/**
* This implementation returns a File reference for the given URI-identified
* resource, provided that it refers to a file in the file system.
* @since 5.0
* @see #getFile(URI)
*/
protected boolean isFile(URI uri) {
try {
if (uri.getScheme().startsWith(ResourceUtils.URL_PROTOCOL_VFS)) {
return VfsResourceDelegate.getResource(uri).isFile();
}
return ResourceUtils.URL_PROTOCOL_FILE.equals(uri.getScheme());
}
catch (IOException ex) {
return false;
}
}
/**
* This implementation returns a File reference for the given URI-identified
* resource, provided that it refers to a file in the file system.
* @see org.springframework.util.ResourceUtils#getFile(java.net.URI, String)
*/
protected File getFile(URI uri) throws IOException {
if (uri.getScheme().startsWith(ResourceUtils.URL_PROTOCOL_VFS)) {
return VfsResourceDelegate.getResource(uri).getFile();
}
return ResourceUtils.getFile(uri, getDescription());
}
/**
* This implementation returns a FileChannel for the given URI-identified
* resource, provided that it refers to a file in the file system.
* @since 5.0
* @see #getFile(URI)
*/
@Override
public ReadableByteChannel readableChannel() throws IOException {
if (isFile()) {
return new FileInputStream(getFile()).getChannel();
}
else {
return super.readableChannel();
}
}
@Override
public boolean exists() {
try {
URL url = getURL();
if (ResourceUtils.isFileURL(url)) {
// Proceed with file system resolution
return getFile().exists();
}
else {
// Try a URL connection content-length header
URLConnection con = url.openConnection();
customizeConnection(con);
HttpURLConnection httpCon =
(con instanceof HttpURLConnection ? (HttpURLConnection) con : null);
if (httpCon != null) {
int code = httpCon.getResponseCode();
if (code == HttpURLConnection.HTTP_OK) {
return true;
}
else if (code == HttpURLConnection.HTTP_NOT_FOUND) {
return false;
}
}
if (con.getContentLength() >= 0) {
return true;
}
if (httpCon != null) {
// no HTTP OK status, and no content-length header: give up
httpCon.disconnect();
return false;
}
else {
// Fall back to stream existence: can we open the stream?
InputStream is = getInputStream();
is.close();
return true;
}
}
}
catch (IOException ex) {
return false;
}
}
@Override
public boolean isReadable() {
try {
URL url = getURL();
if (ResourceUtils.isFileURL(url)) {
// Proceed with file system resolution
File file = getFile();
return (file.canRead() && !file.isDirectory());
}
else {
return true;
}
}
catch (IOException ex) {
return false;
}
}
@Override
public long contentLength() throws IOException {
URL url = getURL();
if (ResourceUtils.isFileURL(url)) {
// Proceed with file system resolution
return getFile().length();
}
else {
// Try a URL connection content-length header
URLConnection con = url.openConnection();
customizeConnection(con);
return con.getContentLength();
}
}
@Override
public long lastModified() throws IOException {
URL url = getURL();
if (ResourceUtils.isFileURL(url) || ResourceUtils.isJarURL(url)) {
// Proceed with file system resolution
try {
return super.lastModified();
}
catch (FileNotFoundException ex) {
// Defensively fall back to URL connection check instead
}
}
// Try a URL connection last-modified header
URLConnection con = url.openConnection();
customizeConnection(con);
return con.getLastModified();
}
/**
* Customize the given {@link URLConnection}, obtained in the course of an
* {@link #exists()}, {@link #contentLength()} or {@link #lastModified()} call.
* <p>Calls {@link ResourceUtils#useCachesIfNecessary(URLConnection)} and
* delegates to {@link #customizeConnection(HttpURLConnection)} if possible.
* Can be overridden in subclasses.
* @param con the URLConnection to customize
* @throws IOException if thrown from URLConnection methods
*/
protected void customizeConnection(URLConnection con) throws IOException {
ResourceUtils.useCachesIfNecessary(con);
if (con instanceof HttpURLConnection) {
customizeConnection((HttpURLConnection) con);
}
}
/**
* Customize the given {@link HttpURLConnection}, obtained in the course of an
* {@link #exists()}, {@link #contentLength()} or {@link #lastModified()} call.
* <p>Sets request method "HEAD" by default. Can be overridden in subclasses.
* @param con the HttpURLConnection to customize
* @throws IOException if thrown from HttpURLConnection methods
*/
protected void customizeConnection(HttpURLConnection con) throws IOException {
con.setRequestMethod("HEAD");
}
/**
* Inner delegate class, avoiding a hard JBoss VFS API dependency at runtime.
*/
private static class VfsResourceDelegate {
public static Resource getResource(URL url) throws IOException {
return new VfsResource(VfsUtils.getRoot(url));
}
public static Resource getResource(URI uri) throws IOException {
return new VfsResource(VfsUtils.getRoot(uri));
}
}
}