Spring Framework example source code file (UrlResource.java)

This example Spring Framework source code file (UrlResource.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Spring Framework tags/keywords

file, inputstream, io, ioexception, ioexception, malformedurlexception, malformedurlexception, net, network, path, resource, string, uri, url, url, urlresource, urlresource

The Spring Framework UrlResource.java source code

/*
 * Copyright 2002-2008 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.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URL;
import java.net.URLConnection;

import org.springframework.util.Assert;
import org.springframework.util.ResourceUtils;
import org.springframework.util.StringUtils;

/**
 * {@link Resource} implementation for <code>java.net.URL locators.
 * Obviously supports resolution as URL, and also as File in case of
 * the "file:" protocol.
 *
 * @author Juergen Hoeller
 * @since 28.12.2003
 * @see java.net.URL
 */
public class UrlResource extends AbstractResource {

	/**
	 * Original URL, used for actual access.
	 */
	private final URL url;

	/**
	 * Cleaned URL (with normalized path), used for comparisons.
	 */
	private final URL cleanedUrl;

	/**
	 * Original URI, if available; used for URI and File access.
	 */
	private final URI uri;


	/**
	 * Create a new UrlResource.
	 * @param url a URL
	 */
	public UrlResource(URL url) {
		Assert.notNull(url, "URL must not be null");
		this.url = url;
		this.cleanedUrl = getCleanedUrl(this.url, url.toString());
		this.uri = null;
	}

	/**
	 * Create a new UrlResource.
	 * @param uri a URI
	 * @throws MalformedURLException if the given URL path is not valid
	 */
	public UrlResource(URI uri) throws MalformedURLException {
		Assert.notNull(uri, "URI must not be null");
		this.url = uri.toURL();
		this.cleanedUrl = getCleanedUrl(this.url, uri.toString());
		this.uri = uri;
	}

	/**
	 * Create a new UrlResource.
	 * @param path a URL path
	 * @throws MalformedURLException if the given URL path is not valid
	 */
	public UrlResource(String path) throws MalformedURLException {
		Assert.notNull(path, "Path must not be null");
		this.url = new URL(path);
		this.cleanedUrl = getCleanedUrl(this.url, path);
		this.uri = null;
	}

	/**
	 * Determine a cleaned URL for the given original URL.
	 * @param originalUrl the original URL
	 * @param originalPath the original URL path
	 * @return the cleaned URL
	 * @see org.springframework.util.StringUtils#cleanPath
	 */
	private URL getCleanedUrl(URL originalUrl, String originalPath) {
		try {
			return new URL(StringUtils.cleanPath(originalPath));
		}
		catch (MalformedURLException ex) {
			// Cleaned URL path cannot be converted to URL
			// -> take original URL.
			return originalUrl;
		}
	}


	/**
	 * This implementation opens an InputStream for the given URL.
	 * It sets the "UseCaches" flag to <code>false,
	 * mainly to avoid jar file locking on Windows.
	 * @see java.net.URL#openConnection()
	 * @see java.net.URLConnection#setUseCaches(boolean)
	 * @see java.net.URLConnection#getInputStream()
	 */
	public InputStream getInputStream() throws IOException {
		URLConnection con = this.url.openConnection();
		con.setUseCaches(false);
		return con.getInputStream();
	}

	/**
	 * This implementation returns the underlying URL reference.
	 */
	public URL getURL() throws IOException {
		return this.url;
	}

	/**
	 * This implementation returns the underlying URI directly,
	 * if possible.
	 */
	public URI getURI() throws IOException {
		if (this.uri != null) {
			return this.uri;
		}
		else {
			return super.getURI();
		}
	}

	/**
	 * This implementation returns a File reference for the underlying URL/URI,
	 * provided that it refers to a file in the file system.
	 * @see org.springframework.util.ResourceUtils#getFile(java.net.URL, String)
	 */
	public File getFile() throws IOException {
		if (this.uri != null) {
			return ResourceUtils.getFile(this.uri, getDescription());
		}
		else {
			return ResourceUtils.getFile(this.url, getDescription());
		}
	}

	/**
	 * This implementation determines the underlying File
	 * (or jar file, in case of a resource in a jar/zip).
	 */
	protected File getFileForLastModifiedCheck() throws IOException {
		if (ResourceUtils.isJarURL(this.url)) {
			URL actualUrl = ResourceUtils.extractJarFileURL(this.url);
			return ResourceUtils.getFile(actualUrl);
		}
		else {
			return getFile();
		}
	}

	/**
	 * This implementation creates a UrlResource, applying the given path
	 * relative to the path of the underlying URL of this resource descriptor.
	 * @see java.net.URL#URL(java.net.URL, String)
	 */
	public Resource createRelative(String relativePath) throws MalformedURLException {
		if (relativePath.startsWith("/")) {
			relativePath = relativePath.substring(1);
		}
		return new UrlResource(new URL(this.url, relativePath));
	}

	/**
	 * This implementation returns the name of the file that this URL refers to.
	 * @see java.net.URL#getFile()
	 * @see java.io.File#getName()
	 */
	public String getFilename() {
		return new File(this.url.getFile()).getName();
	}

	/**
	 * This implementation returns a description that includes the URL.
	 */
	public String getDescription() {
		return "URL [" + this.url + "]";
	}


	/**
	 * This implementation compares the underlying URL references.
	 */
	public boolean equals(Object obj) {
		return (obj == this ||
		    (obj instanceof UrlResource && this.cleanedUrl.equals(((UrlResource) obj).cleanedUrl)));
	}

	/**
	 * This implementation returns the hash code of the underlying URL reference.
	 */
	public int hashCode() {
		return this.cleanedUrl.hashCode();
	}

}