PicoContainer example source code file (CustomPermissionsURLClassLoader.java)

This example PicoContainer source code file (CustomPermissionsURLClassLoader.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - PicoContainer tags/keywords

class, class, classloader, classloader, classnotfoundexception, classnotfoundexception, custompermissionsurlclassloader, map, net, network, object, security, string, string, stringbuffer, the, url, util

The PicoContainer CustomPermissionsURLClassLoader.java source code

/*****************************************************************************
 * Copyright (C) PicoContainer Organization. All rights reserved.            *
 * ------------------------------------------------------------------------- *
 * The software in this package is published under the terms of the BSD      *
 * style license a copy of which has been included with this distribution in *
 * the LICENSE.txt file.                                                     *
 *                                                                           *
 *****************************************************************************/

package org.picocontainer;

import java.net.URL;
import java.net.URLClassLoader;
import java.security.AccessController;
import java.security.CodeSource;
import java.security.PermissionCollection;
import java.security.Permissions;
import java.security.PrivilegedAction;
import java.util.Map;

/**
 * CustomPermissionsURLClassLoader extends URLClassLoader, adding the abilty to programatically add permissions easily.
 * To be effective for permission management, it should be run in conjunction with a policy that restricts
 * some of the classloaders, but not all.
 * It's not ordinarily used by PicoContainer, but is here because PicoContainer is common
 * to most classloader trees.
 * 
 * @author Paul Hammant
 */
public class CustomPermissionsURLClassLoader extends URLClassLoader {
    private final Map permissionsMap;

    public CustomPermissionsURLClassLoader(URL[] urls, Map permissionsMap, ClassLoader parent) {
        super(urls, parent);
        this.permissionsMap = permissionsMap;
    }

    public Class loadClass(String name) throws ClassNotFoundException {
        try {
            return super.loadClass(name);
        } catch (ClassNotFoundException e) {
            throw decorateException(name, e);
        }
    }

    protected Class findClass(String name) throws ClassNotFoundException {
        try {
            return super.findClass(name);
        } catch (ClassNotFoundException e) {
            throw decorateException(name, e);
        }
    }

    private ClassNotFoundException decorateException(String name, ClassNotFoundException e) {
        if (name.startsWith("class ")) {
            return new ClassNotFoundException("Class '" + name + "' is not a classInstance.getName(). " +
                    "It's a classInstance.toString(). The clue is that it starts with 'class ', no classname contains a space.");
        }
        ClassLoader classLoader = this;
        StringBuffer sb = new StringBuffer("'").append(name).append("' classloader stack [");
        while (classLoader != null) {
            sb.append(classLoader.toString()).append("\n");
            final ClassLoader cl = classLoader;
            classLoader = (ClassLoader) AccessController.doPrivileged(new PrivilegedAction() {
                public Object run() {
                    return cl.getParent();
                }
            });

        }
        return new ClassNotFoundException(sb.append("]").toString(), e);
    }

    public String toString() {
        String result = CustomPermissionsURLClassLoader.class.getName() + " " + System.identityHashCode(this) + ":";
        URL[] urls = getURLs();
        for (URL url : urls) {
            result += "\n\t" + url.toString();
        }

        return result;
    }

    public PermissionCollection getPermissions(CodeSource codeSource) {
        return (Permissions) permissionsMap.get(codeSource.getLocation());
    }

}