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 block
e.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
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*/
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 ");
}
}