org.polymap.service.geoserver.GeoServerClassLoader.java Source code

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Here is the source code for org.polymap.service.geoserver.GeoServerClassLoader.java

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/* 
 * polymap.org
 * Copyright 2009-2012, Polymap GmbH. All rights reserved.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 */
package org.polymap.service.geoserver;

import java.util.Arrays;
import java.util.Enumeration;

import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLClassLoader;

import javax.imageio.ImageIO;

import org.osgi.framework.Bundle;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * This ClassLoader acts like a WebAppClassLoader for the GeoServer instances.
 * It helps to start several GeoServers in separate (servlet) contexts.
 * 
 * @see "http://www.devdaily.com/java/jwarehouse/jetty-6.1.9/modules/jetty/src/main/java/org/mortbay/jetty/webapp/WebAppClassLoader.java.shtml"
 * @author <a href="http://www.polymap.de">Falko Braeutigam</a>
 * @since 3.0
 */
public class GeoServerClassLoader extends URLClassLoader {

    private static final Log log = LogFactory.getLog(GeoServerClassLoader.class);

    private ClassLoader parent;

    private String loaderName = "GeoServerClassLoader";

    private boolean isParentLoaderPriority = false;

    public GeoServerClassLoader(ClassLoader parent) {
        super(new URL[] {}, parent);
        this.parent = parent;

        Bundle bundle = GeoServerPlugin.getDefault().getBundle();
        for (Enumeration en = bundle.findEntries("lib/", "*.jar", false); en.hasMoreElements();) {
            URL entry = (URL) en.nextElement();
            log.debug("JAR found: " + entry);
            addURL(entry);
        }

        //  allow GeoServer/Spring to access my classes (have to be included in the bundle)
        addURL(bundle.getResource("build/eclipse/"));

        // Trigger a call to sun.awt.AppContext.getAppContext(). This will pin
        // the common class loader in memory but that shouldn't be an issue. 
        ImageIO.getCacheDirectory();
    }

    public void close() throws IOException {
        try {
            // super.close() is defined in JDK 1.7
            Method m = URLClassLoader.class.getMethod("close", new Class[0]);
            m.invoke(this, new Object[0]);
        } catch (Exception e) {
            log.warn("" + e);
        }
        this.parent = null;
    }

    public URL getResource(String name) {
        //log.debug( "getResource(): path= " + name );
        return super.getResource(name);
    }

    public InputStream getResourceAsStream(String name) {
        //log.debug( "getResourceAsStream(): path= " + name );
        return super.getResourceAsStream(name);
    }

    public Enumeration<URL> getResources(String name) throws IOException {
        //log.debug( "getResources(): path= " + name );
        return super.getResources(name);
    }

    public synchronized Class loadClass(String name) throws ClassNotFoundException {
        return loadClass(name, false);
    }

    protected synchronized Class loadClass(String name, boolean resolve) throws ClassNotFoundException {
        Class c = findLoadedClass(name);
        ClassNotFoundException ex = null;
        boolean tried_parent = false;

        // parent priority?
        if (c == null && parent != null && (isParentLoaderPriority || isSystemPath(name))) {

            tried_parent = true;
            try {
                c = parent.loadClass(name);
            } catch (ClassNotFoundException e) {
                ex = e;
            }
        }
        // find class
        if (c == null) {
            try {
                c = this.findClass(name);
                //log.debug( "loadClass(): name= " + name );
            } catch (ClassNotFoundException e) {
                ex = e;
            }
        }
        // delegate parent
        if (c == null && parent != null && !tried_parent && !isServerPath(name)) {
            c = parent.loadClass(name);
        }
        if (c == null) {
            throw ex;
        }
        if (resolve) {
            resolveClass(c);
        }
        return c;
    }

    public boolean isSystemPath(String name) {
        //log.info( "isSystemPath(): name= " + name );
        name = name.replace('/', '.');
        while (name.startsWith(".")) {
            name = name.substring(1);
        }
        return !name.startsWith("org.geoserver.") && !name.startsWith("org.vfny.") &&
        //                !name.startsWith( "org.springframework." ) &&
        //                !name.startsWith( "org.geotools." ) &&
                !name.startsWith("org.polymap.service.geoserver.spring");
        //!name.startsWith( "sun." );

        //        String[] system_classes = _context.getSystemClasses();
        //        if (system_classes != null) {
        //            for (int i = 0; i < system_classes.length; i++) {
        //                boolean result = true;
        //                String c = system_classes[i];
        //            }
        //            if (c.startsWith( "-" )) {
        //                c = c.substring( 1 ); // TODO cache result=false; }
        //                if (c.endsWith( "." )) {
        //                    if (name.startsWith( c ))
        //                        return result;
        //                }
        //                else if (name.equals( c ))
        //                    return result;
        //            }
        //        }
        //        return false;
    }

    public boolean isServerPath(String name) {
        //log.debug( "isServerPath(): name= " + name );
        name = name.replace('/', '.');
        while (name.startsWith(".")) {
            name = name.substring(1);
        }
        return false;
    }

    public String toString() {
        if (log.isDebugEnabled()) {
            return "ContextLoader@" + loaderName + "(" + Arrays.asList(getURLs()) + ") / " + parent;
        }
        return "ContextLoader@" + loaderName;
    }

}