ThreadLocal類使用

class Channel {  //消息發送通道
    private static final ThreadLocal<Message> THREAD_LOCAL = new ThreadLocal<>();
    public Channel() {}
    public static void setMessage(Message m) {
        THREAD_LOCAL.set(m);
    }
    public static void send() {
        System.out.println("【" + Thread.currentThread().getName() + "消息發送】" + THREAD_LOCAL.get().getInfo());
    }
}

class Message { //消息類
    private String info;
    public void setInfo(String info) {
        this.info = info;
    }
    public String getInfo() {
        return this.info;
    }
}

public class ThreadLocalTest {
    public static void main(String[] args) throws Exception{
//        Message message = new Message();
//        message.setInfo("www.baidu.com");
//        Channel.setMessage(message);
//        Channel.send();
        new Thread(()-> {
            Message msg = new Message();
            msg.setInfo("Thread 1 message.");
            Channel.setMessage(msg);
            Channel.send();
        }, "消息發送者A").start();
        new Thread(()-> {
            Message msg = new Message();
            msg.setInfo("Thread 2 message.");
            Channel.setMessage(msg);
            Channel.send();
        }, "消息發送者B").start();
        new Thread(()-> {
            Message msg = new Message();
            msg.setInfo("Thread 3 message.");
            Channel.setMessage(msg);
            Channel.send();
        }, "消息發送者C").start();
    }
}