Java tutorial
/* * Copyright 2002-2018 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 * * https://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.HttpURLConnection; import java.net.MalformedURLException; import java.net.URI; import java.net.URISyntaxException; import java.net.URL; import java.net.URLConnection; import org.springframework.lang.Nullable; import org.springframework.util.Assert; import org.springframework.util.ResourceUtils; import org.springframework.util.StringUtils; /** * {@link Resource} implementation for {@code java.net.URL} locators. * Supports resolution as a {@code URL} and also as a {@code File} in * case of the {@code "file:"} protocol. * * @author Juergen Hoeller * @since 28.12.2003 * @see java.net.URL */ public class UrlResource extends AbstractFileResolvingResource { /** * Original URI, if available; used for URI and File access. */ @Nullable private final URI uri; /** * Original URL, used for actual access. */ private final URL url; /** * Cleaned URL (with normalized path), used for comparisons. */ private final URL cleanedUrl; /** * Create a new {@code UrlResource} based on the given URI object. * @param uri a URI * @throws MalformedURLException if the given URL path is not valid * @since 2.5 */ public UrlResource(URI uri) throws MalformedURLException { Assert.notNull(uri, "URI must not be null"); this.uri = uri; this.url = uri.toURL(); this.cleanedUrl = getCleanedUrl(this.url, uri.toString()); } /** * Create a new {@code UrlResource} based on the given URL object. * @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 {@code UrlResource} based on a URL path. * <p>Note: The given path needs to be pre-encoded if necessary. * @param path a URL path * @throws MalformedURLException if the given URL path is not valid * @see java.net.URL#URL(String) */ public UrlResource(String path) throws MalformedURLException { Assert.notNull(path, "Path must not be null"); this.uri = null; this.url = new URL(path); this.cleanedUrl = getCleanedUrl(this.url, path); } /** * Create a new {@code UrlResource} based on a URI specification. * <p>The given parts will automatically get encoded if necessary. * @param protocol the URL protocol to use (e.g. "jar" or "file" - without colon); * also known as "scheme" * @param location the location (e.g. the file path within that protocol); * also known as "scheme-specific part" * @throws MalformedURLException if the given URL specification is not valid * @see java.net.URI#URI(String, String, String) */ public UrlResource(String protocol, String location) throws MalformedURLException { this(protocol, location, null); } /** * Create a new {@code UrlResource} based on a URI specification. * <p>The given parts will automatically get encoded if necessary. * @param protocol the URL protocol to use (e.g. "jar" or "file" - without colon); * also known as "scheme" * @param location the location (e.g. the file path within that protocol); * also known as "scheme-specific part" * @param fragment the fragment within that location (e.g. anchor on an HTML page, * as following after a "#" separator) * @throws MalformedURLException if the given URL specification is not valid * @see java.net.URI#URI(String, String, String) */ public UrlResource(String protocol, String location, @Nullable String fragment) throws MalformedURLException { try { this.uri = new URI(protocol, location, fragment); this.url = this.uri.toURL(); this.cleanedUrl = getCleanedUrl(this.url, this.uri.toString()); } catch (URISyntaxException ex) { MalformedURLException exToThrow = new MalformedURLException(ex.getMessage()); exToThrow.initCause(ex); throw exToThrow; } } /** * Determine a cleaned URL for the given original URL. * @param originalUrl the original URL * @param originalPath the original URL path * @return the cleaned URL (possibly the original URL as-is) * @see org.springframework.util.StringUtils#cleanPath */ private URL getCleanedUrl(URL originalUrl, String originalPath) { String cleanedPath = StringUtils.cleanPath(originalPath); if (!cleanedPath.equals(originalPath)) { try { return new URL(cleanedPath); } 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. * <p>It sets the {@code 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() */ @Override public InputStream getInputStream() throws IOException { URLConnection con = this.url.openConnection(); ResourceUtils.useCachesIfNecessary(con); try { return con.getInputStream(); } catch (IOException ex) { // Close the HTTP connection (if applicable). if (con instanceof HttpURLConnection) { ((HttpURLConnection) con).disconnect(); } throw ex; } } /** * This implementation returns the underlying URL reference. */ @Override public URL getURL() { return this.url; } /** * This implementation returns the underlying URI directly, * if possible. */ @Override public URI getURI() throws IOException { if (this.uri != null) { return this.uri; } else { return super.getURI(); } } @Override public boolean isFile() { if (this.uri != null) { return super.isFile(this.uri); } else { return super.isFile(); } } /** * 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) */ @Override public File getFile() throws IOException { if (this.uri != null) { return super.getFile(this.uri); } else { return super.getFile(); } } /** * This implementation creates a {@code 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) */ @Override 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#getPath() */ @Override public String getFilename() { return StringUtils.getFilename(this.cleanedUrl.getPath()); } /** * This implementation returns a description that includes the URL. */ @Override public String getDescription() { return "URL [" + this.url + "]"; } /** * This implementation compares the underlying URL references. */ @Override public boolean equals(@Nullable Object other) { return (this == other || (other instanceof UrlResource && this.cleanedUrl.equals(((UrlResource) other).cleanedUrl))); } /** * This implementation returns the hash code of the underlying URL reference. */ @Override public int hashCode() { return this.cleanedUrl.hashCode(); } }