UIComponentFactory.java

/*
 * Copyright to 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.
 */
package org.rioproject.serviceui;

import net.jini.core.lookup.ServiceItem;
import net.jini.lookup.ui.factory.JComponentFactory;

import javax.swing.*;
import java.io.Serializable;
import java.lang.reflect.Constructor;
import java.net.URL;
import java.net.URLClassLoader;
import java.security.AccessController;
import java.security.PrivilegedAction;

/**
 * The UIComponentFactory class is a helper for use with the ServiceUI
 *
 * @author Dennis Reedy
 */
public class UIComponentFactory implements JComponentFactory, Serializable {
    static final long serialVersionUID = 1L;
    private String className;
    private URL[] exportURL;

    public UIComponentFactory(URL exportUrl, String className) {
        this.className = className;
        this.exportURL = new URL[]{exportUrl};
    }

    public UIComponentFactory(URL[] exportURL, String className) {
        this.className = className;
        this.exportURL = exportURL;
    }

    public JComponent getJComponent(Object roleObject) {
        if(!(roleObject instanceof ServiceItem)) {
            throw new IllegalArgumentException("ServiceItem required");
        }
        ClassLoader cl = ((ServiceItem)roleObject).service.getClass().getClassLoader();
        JComponent component = null;
        try {
            final URLClassLoader uiLoader = new URLClassLoader(exportURL, cl);
            final Thread currentThread = Thread.currentThread();
            final ClassLoader parentLoader = 
                AccessController.doPrivileged(new PrivilegedAction<ClassLoader>() {
                    public ClassLoader run() {
                        return (currentThread.getContextClassLoader());
                    }
                });
            try {
                AccessController.doPrivileged(new PrivilegedAction<Void>() {
                    public Void run() {
                        currentThread.setContextClassLoader(uiLoader);
                        return (null);
                    }
                });
                Class clazz  ;
                try {
                    clazz = uiLoader.loadClass(className);
                } catch(ClassNotFoundException ex) {
                    ex.printStackTrace();
                    throw ex;
                }
                Constructor constructor = clazz.getConstructor(Object.class);
                Object instanceObj = constructor.newInstance(roleObject);
                component = (JComponent)instanceObj;
            } finally {
                AccessController.doPrivileged(new PrivilegedAction<Void>() {
                    public Void run() {
                        currentThread.setContextClassLoader(parentLoader);
                        return (null);
                    }
                });
            }
        } catch(Throwable t) {
            if(t.getCause() != null)
                t = t.getCause();
            IllegalArgumentException e = new IllegalArgumentException("Unable to instantiate ServiceUI :"+className);
            e.initCause(t);
            throw e;
        }
        return (component);
    }
}