Java 异步线程FutureTask的使用和SwingWorker

常用的Thread类在run方法执行完之后是没有返回值的，要实现子线程完成任务后返回值给主线程需要借助第三方转存。Callable接口则提供了一种有返回值的多线程实现方法。 在这里，我们使用FutureTask来实现某种比较耗时的计算，当调用get时如果任务计算完成就会立即返回结果，否则get将阻塞直到任务完成状态。

package Observer;import java.util.concurrent.Callable;import java.util.concurrent.ExecutionException;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.FutureTask;import java.util.concurrent.TimeUnit;import java.util.concurrent.TimeoutException;public class MyFutureTask {public static void main(String[] args) {ExecutorService executorService= Executors.newCachedThreadPool();FutureTask<String> task=new FutureTask<String>(new Callable<String>() {public String call() throws Exception {Thread.sleep(5*1000);return "call ok";}});//executorService.execute(task);executorService.submit(task);//可以提交多个异步任务 long t = System.currentTimeMillis();        try {            String result = task.get(6000, TimeUnit.MILLISECONDS); //取得结果，同时设置超时执行时间为5秒。            System.out.println(result);            System.out.println("fuck");             result = task.get(); //取得结果，同时设置超时执行时间为5秒。            System.err.println("result is " + result + ", time is " + (System.currentTimeMillis() - t));        } catch (InterruptedException e) {        task.cancel(true);            System.err.println("Interrupte time is " + (System.currentTimeMillis() - t));        } catch (ExecutionException e) {        task.cancel(true);            System.err.println("Throw Exception time is " + (System.currentTimeMillis() - t));        } catch (TimeoutException e) {// TODO Auto-generated catch blocke.printStackTrace();} finally {            executorService.shutdown();        }}}

package Observer;import java.util.concurrent.Callable;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.FutureTask;import java.util.concurrent.TimeUnit;public class FutureTaskExample {static class MyCallable implements Callable<String> {private long waitTime;public MyCallable(int timeInMillis) {this.waitTime = timeInMillis;}@Overridepublic String call() throws Exception {Thread.sleep(waitTime);// return the thread name executing this callable taskreturn Thread.currentThread().getName();}}public static void main(String[] args) {        MyCallable callable1 = new MyCallable(2000);        MyCallable callable2 = new MyCallable(8000);         FutureTask<String> futureTask1 = new FutureTask<String>(callable1);        FutureTask<String> futureTask2 = new FutureTask<String>(callable2);         ExecutorService executor = Executors.newFixedThreadPool(2);        executor.execute(futureTask1);        executor.execute(futureTask2);                 while (true) {            try {                if(futureTask1.isDone() && futureTask2.isDone()){                    System.out.println("all Done");                    //shut down executor service                    executor.shutdown();                    return;                }                                                //wait indefinitely for future task to complete                System.out.println("FutureTask1 output="+futureTask1.get());                                                                System.out.println("Waiting for FutureTask2 to complete");                String s = futureTask2.get(10000L, TimeUnit.MILLISECONDS);                if(s !=null){                    System.out.println("FutureTask2 output="+s);                }            } catch(Exception e){                e.printStackTrace();            }        }             }}

package Observer;import java.util.ArrayList;import java.util.List;import java.util.concurrent.Callable;import java.util.concurrent.ExecutionException;import java.util.concurrent.FutureTask;public class FutureTest {public static void main(String[] args) {Preloader preloader = new Preloader();preloader.start();List<String> datas = null;datas = preloader.getDatas();for (String str : datas) {System.out.println(str);}}}class Preloader {private Callable<List<String>> callable = new Callable<List<String>>() {@Overridepublic List<String> call() throws Exception {return downloadData();}};private Thread thread;private FutureTask<List<String>> future;private List<String> downloadData() {List<String> list = new ArrayList<String>();try {Thread.sleep(2000);} catch (InterruptedException e) {e.printStackTrace();}for (int i = 0; i < 10; i++) {list.add("data" + i);}return list;}private void init() {future = new FutureTask<List<String>>(callable);thread = new Thread(future);}public Preloader() {init();}public void start() {thread.start();}public List<String> getDatas() {try {return future.get();} catch (InterruptedException e) {e.printStackTrace();} catch (ExecutionException e) {e.printStackTrace();}return null;}}

SwingWorker

/* * To change this license header, choose License Headers in Project Properties. * To change this template file, choose Tools | Templates * and open the template in the editor. */package com.jiepu.docbuildermanager.demo;import javax.swing.SwingWorker;/** * * @author Administrator */public class TestThread {    public static void main(String[] args) throws Exception {        SwingWorker worker=new SwingWorker<Object, Object>() {            @Override            protected Object doInBackground() throws Exception {                System.out.println("老子是异步线程 来高我啊");                Thread.sleep(1000);                return System.getProperties();            }        };        worker.execute();                 //不用等待异步线程执行完成        System.out.println("ok");        //等待异步线程执行完成        System.out.println(worker.get());                        System.out.println("main thread finish ");    }}