/*
 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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 in the LICENSE file that
 * accompanied this code).
 *
 * 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package sun.net.www.protocol.jar;

import java.io.IOException;
import java.io.FileNotFoundException;
import java.net.URL;
import java.net.URLConnection;
import java.util.HashMap;
import java.util.jar.JarFile;
import java.security.Permission;
import sun.net.util.URLUtil;

/* A factory for cached JAR file. This class is used to both retrieve
 * and cache Jar files.
 *
 * @author Benjamin Renaud
 * @since 1.2
 */
class JarFileFactory implements URLJarFile.URLJarFileCloseController {

    /* the url to file cache */
    private static final HashMap<String, JarFile> fileCache = new HashMap<>();

    /* the file to url cache */
    private static final HashMap<JarFile, URL> urlCache = new HashMap<>();

    private static final JarFileFactory instance = new JarFileFactory();

    private JarFileFactory() { }

    public static JarFileFactory getInstance() {
        return instance;
    }

    URLConnection getConnection(JarFile jarFile) throws IOException {
        URL u;
        synchronized (instance) {
            u = 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;
        JarFile local_result;

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

        return result;
    }

    
Callback method of the URLJarFileCloseController to indicate that the JarFile is close. This way we can remove the JarFile from the cache
/** * Callback method of the URLJarFileCloseController to * indicate that the JarFile is close. This way we can * remove the JarFile from the cache */
public void close(JarFile jarFile) { synchronized (instance) { URL urlRemoved = urlCache.remove(jarFile); if (urlRemoved != null) fileCache.remove(urlKey(urlRemoved)); } } private JarFile getCachedJarFile(URL url) { assert Thread.holdsLock(instance); JarFile result = fileCache.get(urlKey(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 String urlKey(URL url) { String urlstr = URLUtil.urlNoFragString(url); if ("runtime".equals(url.getRef())) urlstr += "#runtime"; return urlstr; } private Permission getPermission(JarFile jarFile) { try { URLConnection uc = getConnection(jarFile); if (uc != null) return uc.getPermission(); } catch (IOException ioe) { // gulp } return null; } }