jarfilefactory.java

来自「This is a resource based on j2me embedde」· Java 代码 · 共 139 行

/*
 * @(#)JarFileFactory.java	1.35 06/10/10
 *
 * Copyright  1990-2008 Sun Microsystems, Inc. All Rights Reserved.  
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER  
 *   
 * This program is free software; you can redistribute it and/or  
 * modify it under the terms of the GNU General Public License version  
 * 2 only, as published by the Free Software Foundation.   
 *   
 * This program is distributed in the hope that it will be useful, but  
 * WITHOUT ANY WARRANTY; without even the implied warranty of  
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU  
 * General Public License version 2 for more details (a copy is  
 * included at /legal/license.txt).   
 *   
 * You should have received a copy of the GNU General Public License  
 * version 2 along with this work; if not, write to the Free Software  
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  
 * 02110-1301 USA   
 *   
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa  
 * Clara, CA 95054 or visit www.sun.com if you need additional  
 * information or have any questions. 
 *
 */

package sun.net.www.protocol.jar;

import java.io.*;
import java.net.*;
import java.util.*;
import java.util.jar.*;
import java.util.zip.ZipFile;
import java.security.Permission;

/* A factory for cached JAR file. This class is used to both retrieve
 * and cache Jar files.
 *
 * @author Benjamin Renaud
 * @since JDK1.2
 */
class JarFileFactory {

    /* the url to file cache */
    private static HashMap fileCache = new HashMap();

    /* the file to url cache */
    private static HashMap urlCache = new HashMap();

    URLConnection getConnection(JarFile jarFile) throws IOException {
	URL u = (URL)urlCache.get(jarFile);
	if (u != null)
	    return u.openConnection();

	return null;
    }

    public JarFile get(URL url) throws IOException {
        return get(url, true);
    }

    JarFile get(URL url, boolean useCaches) throws IOException {

	JarFile result = null;
        JarFile local_result = null;
	
	if (useCaches) {
	    synchronized (this) {
		result = getCachedJarFile(url);
	    }
	    if (result == null) {
		local_result = URLJarFile.getJarFile(url);
		synchronized (this) {
		    result = getCachedJarFile(url);
		    if (result == null) {
			fileCache.put(url, local_result);
			urlCache.put(local_result, url);
			result = local_result;
		    } else {
			if (local_result != null) {
			    local_result.close();
			}
		    }
		}
	    } 
	}else {
	    result = URLJarFile.getJarFile(url);
	}
	if (result == null) 
	    throw new FileNotFoundException(url.toString());
	
	return result;
    }

    private JarFile getCachedJarFile(URL url) {
	JarFile result = (JarFile)fileCache.get(url);

	/* if the JAR file is cached, the permission will always be there */
	if (result != null) {
	    Permission perm = getPermission(result);
	    if (perm != null) {
		SecurityManager sm = System.getSecurityManager();
		if (sm != null) {
		    try {
			sm.checkPermission(perm);
		    } catch (SecurityException se) {
			// fallback to checkRead/checkConnect for pre 1.2
			// security managers
			if ((perm instanceof java.io.FilePermission) &&
			    perm.getActions().indexOf("read") != -1) {
			    sm.checkRead(perm.getName());
			} else if ((perm instanceof 
			    java.net.SocketPermission) &&
			    perm.getActions().indexOf("connect") != -1) {
			    sm.checkConnect(url.getHost(), url.getPort());
			} else {
			    throw se;
			}
		    }
		}
	    }
	}
	return result;
    }

    private Permission getPermission(JarFile jarFile) {
	try {
	    URLConnection uc = (URLConnection)getConnection(jarFile);
	    if (uc != null)
		return uc.getPermission();
	} catch (IOException ioe) {
	    // gulp
	}

	return null;
    }
}