StateHelper帮助JMF中Player和Processor进行状态过度，,MF中Player和Pr

StateHelper帮助JMF中Player和Processor进行状态过度，,MF中Player和Pr

MF中Player和Processor的configure(),realize()等方法是异步的，会马上返回；而用StateHelper调用这些方法会阻塞，直到状态过度好了或者timeout了才返回.代码来自 JMF Media Framework API Guide

import javax.media.*;public class StateHelper implements ControllerListener{    public StateHelper (Player p) {        player = p;        p.addControllerListener(this);    }    public boolean configure (int timeOutMillis) {        long startTime = System.currentTimeMillis();        synchronized (this) {            if (player instanceof Processor)                ((Processor)player).configure();            else                return false;            while(!configured && !failed) {                try {                    wait(timeOutMillis);                } catch (InterruptedException e) {                    // TODO: handle exception                }                if(System.currentTimeMillis() - startTime > timeOutMillis)                    break;            }        }        return configured;    }    public boolean prefetch(int timeOutMillis) {        long startTime = System.currentTimeMillis();        synchronized (this) {            player.prefetch();            while(!prefetched && !failed) {                try {                    wait(timeOutMillis);                } catch (InterruptedException e) {                    // TODO: handle exception                }                if(System.currentTimeMillis() - startTime > timeOutMillis)                    break;            }        }        return prefetched && !failed;    }    public boolean realize(int timeOutMillis) {        long startTime = System.currentTimeMillis();        synchronized (this) {            player.realize();            while(!realized && !failed) {                try {                    wait(timeOutMillis);                } catch (InterruptedException e) {                    // TODO: handle exception                }                if(System.currentTimeMillis() - startTime > timeOutMillis)                    break;            }        }        return realized;    }    public boolean playToEndOfMedia(int timeOutMillis) {        long startTime = System.currentTimeMillis();        eom = false;        synchronized (this) {            player.start();            while(!eom && !failed) {                try {                    wait(timeOutMillis);                } catch (InterruptedException e) {                    // TODO: handle exception                }                if(System.currentTimeMillis() - startTime > timeOutMillis)                    break;            }        }        return eom && !failed;    }    public void close() {        synchronized (this) {            player.close();            while(!closed) {                try {                    wait(100);                } catch (InterruptedException e) {                    // TODO: handle exception                }            }        }        player.removeControllerListener(this);    }    @Override    public synchronized void controllerUpdate(ControllerEvent e) {        if(e instanceof RealizeCompleteEvent) {            realized = true;        } else if(e instanceof ConfigureCompleteEvent) {            configured = true;        } else if(e instanceof PrefetchCompleteEvent) {            prefetched = true;        } else if(e instanceof EndOfMediaEvent) {            eom = true;        } else if(e instanceof ControllerErrorEvent) {            failed = true;        } else if(e instanceof ControllerClosedEvent) {            closed = true;        } else {            return;        }        notifyAll();            }    boolean configured = false;    boolean realized = false;    boolean prefetched = false;    boolean closed = false;    boolean failed = false;    boolean eom = false;    Player player = null;}//该片段来自于http://byrx.net