用 Exchanger两个线程之间的通信

01 Exchanger 作用

使两个线程之间进行数据传递。（对是两个之间而不是三个或者更多个线程之间）

02 常用方法

exchange（） 阻塞当前线程并等待其他线程来取得数据，若没有其他线程来取数据则一直等待。

exchange（） 传递数据

exchange(V v, long timeout, TimeUnit unit) 在指定的时间内没收到消息，则抛出超时的异常。

03 例子

package com.page.concurrent.exchanger;

import java.util.concurrent.Exchanger;

public class Worker extends Thread {

    private final String name;
    Exchanger<String> exchanger;

    public Worker(String name, Exchanger<String> exchanger) {
        this.name = name;
        this.exchanger = exchanger;
    }

    @Override
    public void run() {
        System.out.println(Thread.currentThread().getName() + " : " +
                System.currentTimeMillis() +
                " " + name +
                " waiting message.");

        try {
            String exchange = exchanger.exchange("I'm " + name);
            System.out.println(name + " get message : " + exchange);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

    }
}

package com.page.concurrent.exchanger;

import java.util.concurrent.Exchanger;

public class App {
    public static void main(String[] args) {
        Exchanger<String> exchanger = new Exchanger<>();

        for (int i = 1; i <= 2; i++) {
            new Worker("people-" + i, exchanger)
                    .start();
        }
    }
}