Java如何实现异步多线程呢?

写在前面的话:
    以前我们执行异步多任务,采用下面的代码
    new Thread (new Runnable(){
    public void run(){
        //异步逻辑
		}
	}).start

//但是这么写有一个缺点:
   1.new Thread 新建线程时,性能很差
   2.线程缺乏统一管理,可能无限制新建线程,相互之间竞争,及可能占用过多系统资源导致死机或oom资源耗尽。
   3.此种创建线程方式:如定时执行、定期执行、线程中断

package com.java265.thread;

import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
public class MyThreadPool {

    public static void main(String [] args){
        Executor executor = Executors.newFixedThreadPool(10);
        for (int i = 0 ; i<8 ; i++){
            executor.execute(new Runnable() {
                @Override
                public void run() {
                    System.out.println("我是一个子线程!!");
                }
            });
        }
    }
}

在Java5之后
  任务分两类:
   一类是实现了Runnable接口的类(Thread类也是实现了Runnable接口)
   一类是实现了Callable接口的类
  两者都可以被ExecutorService执行
  但Runnable任务没有返回值,而Callable任务有返回值
   Callable的call()方法只能通过ExecutorService的(task)方法来执行,且返回一个,是表示任务等待完成Future

 
package com.java265.thread;

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

public class MyCallBackThread implements Callable<String> {

    public static void main(String [] args) throws Exception{
        ExecutorService executor = Executors.newFixedThreadPool(10);
        //void execute(Runnable command);
        //实现Callable接口的线程需要使用executor.submit(Callable command )
        Future<String> submit = executor.submit(new MyCallBackThread());
        System.out.println(submit.get());

    }

    @Override
    public String call() throws Exception {
        System.out.println("我是一个Callable子线程");
        return "this is Callable thread return ";
    }
}