Future Parttern 先给你这张提货单

来源：互联网发布：乔任梁与网络暴力编辑：程序博客网时间：2024/05/23 01:17

Future是未来，预期的意思，Thread-permessage模式是指将任务交给其他线程来做，但是如果想知道处理的结果，就要使用Future模式，它的典型应用时执行一个需要花一些时间的方法，会立即返回一个future提货单，然后调用方可以继续处理自己的业务逻辑，然后需要的时候再查看future是否返回，一直等到future结果已经处理完毕。

thread-pre-message模式发送的请求很像这样 host.request(10，‘A’），只有请求，没有返回值，而future pattern模式发送请求后会马上就要有返回值，类似这样 Data data=host.request(10,'A')，但是这个data并不是程序执行的结果，只是一个提货单，过一段时间后，可以使用data.getContent()来获取真正的运行结果，调用getContent方法时，如果还没处理完毕，就要等待到处理好为止。

public class FutureThreadTest {    /**     * @param args     */    public static void main(String[] args) {        System.out.println("main begin.");        Host host = new Host();        Data data1 = host.request(30,'A');        Data data2 = host.request(20,'B');        Data data3 = host.request(10,'C');                System.out.println("main other job begin");        try {            Thread.sleep(3000);        } catch (InterruptedException e) {            e.printStackTrace();        }                System.out.println("main other job end");                System.out.println("data1 = " + data1.getContent());        System.out.println("data2 = " + data2.getContent());        System.out.println("data3 = " + data3.getContent());    }}class Host {    public Data request(final int count, final char c) {        System.out.println("request(" + count + "," + c + ")begin");        final FutureData future = new FutureData();        new Thread() {            @Override            public void run() {                RealData realdata = new RealData(count, c);                future.setRealData(realdata);            }        }.start();        System.out.println("request(" + count + ", " + c + ")end");        return future;    }}interface Data{    public abstract String getContent();}class FutureData implements Data{    private RealData realdata = null;    private boolean ready = false;        public synchronized void setRealData(RealData realdata){        if(ready){            return;        }                this.realdata=realdata;        this.ready=true;                notify();    }        @Override    public synchronized String getContent() {        while(!ready){            try {                wait();            } catch (InterruptedException e) {                e.printStackTrace();            }        }        return realdata.getContent();    }}class RealData implements Data {    private final String content;    public RealData(int count, char c) {        System.out.println("making realdata(" + count + "," + c + ")begin");        char[] buffer = new char[count];        for (int i = 0; i < count; i++) {            buffer[i] = c;            try {                Thread.sleep(100);            } catch (InterruptedException e) {                e.printStackTrace();            }        }        System.out.println("making realdata(" + count + "," + c + ")end");        this.content = new String(buffer);    }    @Override    public String getContent() {        return content;    }}

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