中间桥梁，将互相不联系的事物联系起来。

public abstract class Colleague {    protected Mediator mediator;    /**     * 用于表示几件事物的统一性，最起码是同一个媒介     *     * @param mediator     */    public Colleague(Mediator mediator) {        this.mediator = mediator;    }}

public class CDDevice extends Colleague {    private String data;    /**     * CD唱片，包括音频，视频     * @param mediator     */    public CDDevice(Mediator mediator) {        super(mediator);    }    public String read() {        return data;    }    public void load() {        data = "视频数据,音频数据";        mediator.changed(this);        // 媒介分发数据    }}

public class CPU extends Colleague {    private String video, sound;    public CPU(Mediator mediator) {        super(mediator);    }    public String getVideo() {        return video;    }    /**     * 解析数据     *     * @param data     */    public void decodeData(String data) {        String[] tmp = data.split("");        video = tmp[0];        sound = tmp[1];        mediator.changed(this);    }    public String getSound() {        return sound;    }}

public class GraphicsCard extends Colleague {    public GraphicsCard(Mediator mediator) {        super(mediator);    }    /**     * 视频数据处理     *     * @param data     */    public void videoPlay(String data) {        System.out.print("视频：" + data);    }}

public class SoundCard extends Colleague {    public SoundCard(Mediator mediator) {        super(mediator);    }    /**     * 音频数据处理     * @param data     */    public void soundPlay(String data){        System.out.print("音频："+  data);    }}

public abstract class Mediator {    /**     * 通知中介改变     *     * @param c     */    abstract void changed(Colleague c);}

public class MainBoard extends Mediator {    private CDDevice cdDevice;    private CPU cpu;    private GraphicsCard graphicsCard;    private SoundCard soundCard;    @Override    void changed(Colleague c) {        if (c == cdDevice) {            cdDevice = (CDDevice) c;            cpu.decodeData(cdDevice.read());        } else if (c == cpu) {            cpu = (CPU) c;            soundCard.soundPlay(cpu.getVideo());            graphicsCard.videoPlay(cpu.getSound());        }    }    public MainBoard setCdDevice(CDDevice cdDevice) {        this.cdDevice = cdDevice;        return this;    }    public MainBoard setCPU(CPU cpu) {        this.cpu = cpu;        return this;    }    public MainBoard setGraphicsCard(GraphicsCard graphicsCard) {        this.graphicsCard = graphicsCard;        return this;    }    public MainBoard setSoundCard(SoundCard soundCard) {        this.soundCard = soundCard;        return this;    }}

public static void main(String[] args) {    MainBoard mediator = new MainBoard();    CDDevice cdDevice = new CDDevice(mediator);    CPU cpu = new CPU(mediator);    GraphicsCard graphicsCa = new GraphicsCard(mediator);    SoundCard soundCard = new SoundCard(mediator);    mediator.setCdDevice(cdDevice).setCPU(cpu).setGraphicsCard(graphicsCa).setSoundCard(soundCard);    cdDevice.load();      //  CD开始放片}