Java并发程序设计（十）设计模式与并发之Future模式

设计模式与并发之Future模式

核心思想：异步调用。

 

/**
 * @author: Tang Jiujia
 * @version: 2017/9/18 0018 15:22
 */
public interface Data {

    String getResult();
}

/**
 * @author: Tang Jiujia
 * @version: 2017/9/18 0018 15:23
 */
public class RealData implements Data{

    protected final String result;

    public RealData(String para){
        StringBuffer bf=new StringBuffer();
        for (int i=0;i<10;i++){
            bf.append(para);
            try{
                   Thread.sleep(100);
                }catch (Exception e){
                    e.printStackTrace();
                }
        }
        result=bf.toString();
    }

    @Override
    public String getResult() {
        return result;
    }
}

public class FutureData implements Data{

    protected RealData realData=null;
    protected boolean isReady=false;

    public synchronized void setRealData(RealData realData){
        if(isReady){
           return;
        }

        this.realData=realData;
        isReady=true;
        notifyAll();
    }

    @Override
    public synchronized String getResult() {
        while (!isReady){
            try{
                 wait();
                }catch (Exception e){
                    e.printStackTrace();
                }
        }
        return realData.result;
    }
}

public class Client {

    public Data request(final String queryStr){
        final FutureData futureData=new FutureData();
        new Thread(){
            @Override
            public void run(){
                RealData realData=new RealData(queryStr);
                futureData.setRealData(realData);
            }
        }.start();

        return futureData; //立即返回了futureData
    }
}

public class MainClass {

    public static void main(String[] args){
        Client client=new Client();
        Data data=client.request("name");
        System.out.println("请求完毕");
        try{
             Thread.sleep(2000);
            }catch (Exception e){
                e.printStackTrace();
            }
            System.out.println("数据="+data.getResult());
    }
}