继承Callable接口从任务中产生返回值
Runnale是执行工作的独立任务，但是它不会返回任何值。 如果你希望任务在执行完成后能够返回一个值，那么可以实现Callable接口。
package threadpool;import java.util.concurrent.Callable;/** * * @author hewei * * Runnable是执行工作的独立任务，但是它不返回任何值 实现Callable接口可以实现返回值 */public class TaskWithResult implements Callable<String> {private int id;public TaskWithResult(int id) {this.id = id;}@Overridepublic String call() throws Exception {Thread.sleep(1000);return "报告老大 ...线程" + id+" 执行完毕";}}package threadpool;import java.util.ArrayList;import java.util.concurrent.ExecutionException;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;import java.util.concurrent.Future;public class CallableDemo {public static void main(String[] args) {ExecutorService exec = Executors.newSingleThreadExecutor();ArrayList<Future<String>> results = new ArrayList<Future<String>>();for(int i=0;i<10;i++){results.add(exec.submit(new TaskWithResult(i)));}for(Future<String> fs : results){try {System.out.println(fs.get()); //fs.get() 为阻塞方法} catch (InterruptedException | ExecutionException e) {// TODO Auto-generated catch blocke.printStackTrace();}}try {Thread.sleep(1000);} catch (InterruptedException e) {// TODO Auto-generated catch blocke.printStackTrace();}exec.shutdown();exec.shutdownNow();}}