FutureTask浅析

package com.lzq.test;

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class TestFuture {

    public static void main(String[] args) {

        // 通过线程池来创建FutureTask
        ExecutorService executor = Executors.newFixedThreadPool(3);
        try {
            // 测试包装runnable
            Future<?> run = executor.submit(new Runnable() {
                @Override
                public void run() {
                    System.out.println("runnable");
                }
            });
            System.out.println("runable:" + run.get());

            // 测试包装callable
            Future<String> call = executor.submit(new Callable<String>() {
                @Override
                public String call() throws Exception {
                    return "call";
                }
            });

            // 调用get方法，当前线程会阻塞，等待任务执行完毕后才往下执行，适合耗时的运算
            System.out.println("call: " + call.get());
            // 测试cancel
            Future<String> cancelFuture = executor
                    .submit(new Callable<String>() {
                        @Override
                        public String call() throws Exception {
                            try {
                                while (true) {
                                    System.out.println("cancel running.");
                                    Thread.sleep(50);
                                }
                            } catch (InterruptedException e) {
                                System.out.println("Interrupted");
                            }
                            return "cancel false";
                        }
                    });

            System.out.println("cancel: " + cancelFuture.cancel(true));

            // 测试抛异常
            Future<String> exception = executor.submit(new Callable<String>() {

                @Override
                public String call() throws Exception {
                    throw new Exception("new exception!");
                }

            });
            System.out.println("exception: " + exception.get());
        } catch (Exception e) {
            System.out.println(e.toString());
        }

        // 线程他关闭
        executor.shutdownNow();
    }
}

FutureTask<String> ft = new FutureTask<String>(new Callable<String>() {
            @Override
            public String call() throws Exception {
                return "call";
            }
        });
        
        Thread thread = new Thread(ft);
        thread.start();