java:Observable/Observer模式在SWT环境下UI线程/非UI线程的透明化调用

package net.gdface.ui;

import java.util.Observable;
import java.util.Observer;
import java.util.Vector;

import org.eclipse.swt.widgets.Display;

/**
 * SWT环境下对{@link Observable}的易用性封装<br>
 * 实现{@link Observer}类型的侦听器在SWT下UI线程/非UI线程的透明化调用
 * @author guyadong
 *
 */
public class SWTObservable extends Observable {
    /**
     * {@link Observer}在SWT环境下的重新封装<br>
     * 实现UI/非UI线程透明化
     * @author guyadong
     *
     */
    class SWTObserver implements Observer {
        final Observer observer;
        /**
         * 私有构造方法
         * @param observer
         */
        private SWTObserver(Observer observer) {
            super();
            if (null == observer)
                throw new IllegalArgumentException("the argument observer must not be null");       
            this.observer = observer;
        }
        @Override
        public void update(Observable o, Object arg) {
            // 判断UI/非UI线程，区别对待
            if (display.getThread() == Thread.currentThread()) {
                observer.update(o, arg);
            } else {
                // 非UI线程下调用 Display.syncExec方法执行
                display.syncExec(new Runnable() {
                    @Override
                    public void run() {
                        observer.update(o, arg);
                    }
                });
            }
        }
    }
    /**
     * 保存所有被 {@link Observable#addObserver(Observer)}方法添加的 {@link SWTObserver}对象，<br>
     * 以便在 {@link Observable#deleteObserver(Observer)}删除{@link Observer}对象时查找到对应的{@link SWTObserver}对象
     */
    private final Vector<SWTObserver> listeners=new Vector<SWTObserver>();
    private final Display display;
    SWTObservable(Display display) {
        if (null == display)
            throw new IllegalArgumentException("the argument display must not be null");        
        this.display = display;
    }
    /**
     * 在 {@link #listeners}中 查找{@link Observer}对应的{@link SWTObserver}对象，找不到则返回null
     * @param listener
     * @return
     */
    private SWTObserver find(Observer listener){
        for(SWTObserver o:this.listeners){
            if(o.observer==listener)return o;
        }
        return null;
    }
    @Override
    public synchronized void addObserver(Observer o) {
        add(o); 
    }

    @Override
    public synchronized void deleteObserver(Observer o) {
        delete(o);
    }
    synchronized SWTObserver add(Observer o) {
        if (null==find(o)) {
            SWTObserver obs = new SWTObserver(o);
            this.listeners.add(obs);
            super.addObserver(obs);
            return obs;
        }       
        return null;
    }
    synchronized SWTObserver delete(Observer o) {
        SWTObserver obs = find(o);
        if(null!=obs){
            this.listeners.remove(obs);
            super.deleteObserver(obs);
        }
        return obs; 
    }
    @Override
    public void notifyObservers(Object arg) {
        setChanged();
        super.notifyObservers(arg);
    }
}