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());
     }
 }