package currentTest.BlockingQueue;import java.util.concurrent.Callable;import java.util.concurrent.ExecutionException;import java.util.concurrent.FutureTask;/** * 测试FutureTask的用法，如果不想分支线程阻塞主线程，又想取得分支线程的执行结果，就用FutureTask *  * @author zhailzh *  */public class FutureTaskTest {    /**     * @param args     */    public static void main(String[] args) {        CountNum cn = new CountNum(0);        // FutureTask<Integer> 这里的表示返回的是Integer        FutureTask<Integer> ft = new FutureTask<Integer>(cn);        Thread td = new Thread(ft);        System.out.println("futureTask执行计算:" + System.currentTimeMillis());        td.start();        System.out.println("main 主线程可以做些其他事情" + System.currentTimeMillis());        try {            // futureTask的get方法会阻塞，知道可以取得结果为止            Integer result = ft.get();            System.out.println("计算的结果是:" + result);        } catch (InterruptedException e) {            e.printStackTrace();        } catch (ExecutionException e) {            e.printStackTrace();        }        System.out.println("取得分支线程执行的结果后，主线程可以继续处理其他事项");    }}class CountNum implements Callable {    private Integer sum;    public CountNum(Integer sum) {        this.sum = sum;    }    public Object call() throws Exception {        for (int i = 0; i < 100; i++) {            sum = sum + i;        }        // 休眠5秒钟，观察主线程行为，预期的结果是主线程会继续执行，到要取得FutureTask的结果是等待直至完成        Thread.sleep(3000);        System.out.println("futureTask 执行完成" + System.currentTimeMillis());        return sum;    }}