ResourceUtils.java Source code

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Here is the source code for ResourceUtils.java

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/*
 * Copyright 2002-2007 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.
 */

import java.io.File;
import java.io.FileNotFoundException;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLDecoder;

/**
 * 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;
        }
    }

    /**
     * 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;
        }
    }

}