Java tutorial
/* * 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 com.jeeframework.util.classes; import java.io.File; import java.io.FileNotFoundException; import java.net.MalformedURLException; import java.net.URI; import java.net.URISyntaxException; import java.net.URL; import com.jeeframework.util.string.StringUtils; import com.jeeframework.util.validate.Assert; /** * Utility methods for resolving resource locations to files in the * file system. Mainly for internal use within the framework. * * <p>Consider using Spring's Resource abstraction in the core package * for handling all kinds of file resources in a uniform manner. * {@link org.springframework.core.io.ResourceLoader}'s <code>getResource</code> * method can resolve any location to a {@link org.springframework.core.io.Resource} * object, which in turn allows to obtain a <code>java.io.File</code> in the * file system through its <code>getFile()</code> method. * * <p>The main reason for these utility methods for resource location handling * is to support {@link Log4jConfigurer}, which must be able to resolve * resource locations <i>before the logging system has been initialized</i>. * Spring' Resource abstraction in the core package, on the other hand, * already expects the logging system to be available. * * @author Juergen Hoeller * @since 1.1.5 * @see org.springframework.core.io.Resource * @see org.springframework.core.io.ClassPathResource * @see org.springframework.core.io.FileSystemResource * @see org.springframework.core.io.UrlResource * @see org.springframework.core.io.ResourceLoader */ public abstract class ResourceUtils { /** Pseudo URL prefix for loading from the class path: "classpath:" */ public static final String CLASSPATH_URL_PREFIX = "classpath:"; /** URL prefix for loading from the file system: "file:" */ public static final String FILE_URL_PREFIX = "file:"; /** URL protocol for a file in the file system: "file" */ public static final String URL_PROTOCOL_FILE = "file"; /** URL protocol for an entry from a jar file: "jar" */ public static final String URL_PROTOCOL_JAR = "jar"; /** URL protocol for an entry from a zip file: "zip" */ public static final String URL_PROTOCOL_ZIP = "zip"; /** URL protocol for an entry from a WebSphere jar file: "wsjar" */ public static final String URL_PROTOCOL_WSJAR = "wsjar"; /** URL protocol for an entry from an OC4J jar file: "code-source" */ public static final String URL_PROTOCOL_CODE_SOURCE = "code-source"; /** Separator between JAR URL and file path within the JAR */ public static final String JAR_URL_SEPARATOR = "!/"; /** * Return whether the given resource location is a URL: * either a special "classpath" pseudo URL or a standard URL. * @param resourceLocation the location String to check * @return whether the location qualifies as a URL * @see #CLASSPATH_URL_PREFIX * @see java.net.URL */ public static boolean isUrl(String resourceLocation) { if (resourceLocation == null) { return false; } if (resourceLocation.startsWith(CLASSPATH_URL_PREFIX)) { return true; } try { new URL(resourceLocation); return true; } catch (MalformedURLException ex) { return false; } } /** * Resolve the given resource location to a <code>java.net.URL</code>. * <p>Does not check whether the URL actually exists; simply returns * the URL that the given location would correspond to. * @param resourceLocation the resource location to resolve: either a * "classpath:" pseudo URL, a "file:" URL, or a plain file path * @return a corresponding URL object * @throws FileNotFoundException if the resource cannot be resolved to a URL */ public static URL getURL(String resourceLocation) throws FileNotFoundException { Assert.notNull(resourceLocation, "Resource location must not be null"); if (resourceLocation.startsWith(CLASSPATH_URL_PREFIX)) { String path = resourceLocation.substring(CLASSPATH_URL_PREFIX.length()); URL url = ClassUtils.getDefaultClassLoader().getResource(path); if (url == null) { String description = "class path resource [" + path + "]"; throw new FileNotFoundException( description + " cannot be resolved to URL because it does not exist"); } return url; } try { // try URL return new URL(resourceLocation); } catch (MalformedURLException ex) { // no URL -> treat as file path try { return new File(resourceLocation).toURI().toURL(); } catch (MalformedURLException ex2) { throw new FileNotFoundException("Resource location [" + resourceLocation + "] is neither a URL not a well-formed file path"); } } } /** * Resolve the given resource location to a <code>java.io.File</code>, * i.e. to a file in the file system. * <p>Does not check whether the fil actually exists; simply returns * the File that the given location would correspond to. * @param resourceLocation the resource location to resolve: either a * "classpath:" pseudo URL, a "file:" URL, or a plain file path * @return a corresponding File object * @throws FileNotFoundException if the resource cannot be resolved to * a file in the file system */ public static File getFile(String resourceLocation) throws FileNotFoundException { Assert.notNull(resourceLocation, "Resource location must not be null"); if (resourceLocation.startsWith(CLASSPATH_URL_PREFIX)) { String path = resourceLocation.substring(CLASSPATH_URL_PREFIX.length()); String description = "class path resource [" + path + "]"; URL url = ClassUtils.getDefaultClassLoader().getResource(path); if (url == null) { throw new FileNotFoundException(description + " cannot be resolved to absolute file path " + "because it does not reside in the file system"); } return getFile(url, description); } try { // try URL return getFile(new URL(resourceLocation)); } catch (MalformedURLException ex) { // no URL -> treat as file path return new File(resourceLocation); } } /** * Resolve the given resource URL to a <code>java.io.File</code>, * i.e. to a file in the file system. * @param resourceUrl the resource URL to resolve * @return a corresponding File object * @throws FileNotFoundException if the URL cannot be resolved to * a file in the file system */ public static File getFile(URL resourceUrl) throws FileNotFoundException { return getFile(resourceUrl, "URL"); } /** * Resolve the given resource URL to a <code>java.io.File</code>, * i.e. to a file in the file system. * @param resourceUrl the resource URL to resolve * @param description a description of the original resource that * the URL was created for (for example, a class path location) * @return a corresponding File object * @throws FileNotFoundException if the URL cannot be resolved to * a file in the file system */ public static File getFile(URL resourceUrl, String description) throws FileNotFoundException { Assert.notNull(resourceUrl, "Resource URL must not be null"); if (!URL_PROTOCOL_FILE.equals(resourceUrl.getProtocol())) { throw new FileNotFoundException(description + " cannot be resolved to absolute file path " + "because it does not reside in the file system: " + resourceUrl); } try { return new File(toURI(resourceUrl).getSchemeSpecificPart()); } catch (URISyntaxException ex) { // Fallback for URLs that are not valid URIs (should hardly ever happen). return new File(resourceUrl.getFile()); } } /** * Resolve the given resource URI to a <code>java.io.File</code>, * i.e. to a file in the file system. * @param resourceUri the resource URI to resolve * @return a corresponding File object * @throws FileNotFoundException if the URL cannot be resolved to * a file in the file system */ public static File getFile(URI resourceUri) throws FileNotFoundException { return getFile(resourceUri, "URI"); } /** * Resolve the given resource URI to a <code>java.io.File</code>, * i.e. to a file in the file system. * @param resourceUri the resource URI to resolve * @param description a description of the original resource that * the URI was created for (for example, a class path location) * @return a corresponding File object * @throws FileNotFoundException if the URL cannot be resolved to * a file in the file system */ public static File getFile(URI resourceUri, String description) throws FileNotFoundException { Assert.notNull(resourceUri, "Resource URI must not be null"); if (!URL_PROTOCOL_FILE.equals(resourceUri.getScheme())) { throw new FileNotFoundException(description + " cannot be resolved to absolute file path " + "because it does not reside in the file system: " + resourceUri); } return new File(resourceUri.getSchemeSpecificPart()); } /** * Determine whether the given URL points to a resource in a jar file, * that is, has protocol "jar", "zip", "wsjar" or "code-source". * <p>"zip" and "wsjar" are used by BEA WebLogic Server and IBM WebSphere, respectively, * but can be treated like jar files. The same applies to "code-source" URLs on Oracle * OC4J, provided that the path contains a jar separator. * @param url the URL to check * @return whether the URL has been identified as a JAR URL */ public static boolean isJarURL(URL url) { String protocol = url.getProtocol(); return (URL_PROTOCOL_JAR.equals(protocol) || URL_PROTOCOL_ZIP.equals(protocol) || URL_PROTOCOL_WSJAR.equals(protocol) || (URL_PROTOCOL_CODE_SOURCE.equals(protocol) && url.getPath().indexOf(JAR_URL_SEPARATOR) != -1)); } /** * Extract the URL for the actual jar file from the given URL * (which may point to a resource in a jar file or to a jar file itself). * @param jarUrl the original URL * @return the URL for the actual jar file * @throws MalformedURLException if no valid jar file URL could be extracted */ public static URL extractJarFileURL(URL jarUrl) throws MalformedURLException { String urlFile = jarUrl.getFile(); int separatorIndex = urlFile.indexOf(JAR_URL_SEPARATOR); if (separatorIndex != -1) { String jarFile = urlFile.substring(0, separatorIndex); try { return new URL(jarFile); } catch (MalformedURLException ex) { // Probably no protocol in original jar URL, like "jar:C:/mypath/myjar.jar". // This usually indicates that the jar file resides in the file system. if (!jarFile.startsWith("/")) { jarFile = "/" + jarFile; } return new URL(FILE_URL_PREFIX + jarFile); } } else { return jarUrl; } } /** * Create a URI instance for the given URL, * replacing spaces with "%20" quotes first. * <p>Furthermore, this method works on JDK 1.4 as well, * in contrast to the <code>URL.toURI()</code> method. * @param url the URL to convert into a URI instance * @return the URI instance * @throws URISyntaxException if the URL wasn't a valid URI * @see java.net.URL#toURI() */ public static URI toURI(URL url) throws URISyntaxException { return toURI(url.toString()); } /** * Create a URI instance for the given location String, * replacing spaces with "%20" quotes first. * @param location the location String to convert into a URI instance * @return the URI instance * @throws URISyntaxException if the location wasn't a valid URI */ public static URI toURI(String location) throws URISyntaxException { return new URI(StringUtils.replace(location, " ", "%20")); } }