java - 在线程上调用方法 - 它可以工作，但为什么呢？

Question

我有以下 Thread 子类(为了便于阅读而稍微简化):

public class ConnectionHandlerThread extends Thread {
    private Socket socket;
    private volatile boolean disconnected = false;
    private ObjectOutputStream out = null;
    private ObjectInputStream in = null;

    public ConnectionHandlerThread(Socket socket){
        this.socket = socket;
    }

    public void run(){
        disconnected = false;

        try {           
            out = new ObjectOutputStream(socket.getOutputStream());
            in = new ObjectInputStream(socket.getInputStream());

            while(!disconnected){
                try{
                    Object data = in.readObject();                  
                }
                catch(ClassNotFoundException e){
                    // Handle exception
                }               
                catch(IOException e){
                    // Handle exception
                }
            }
        } 
        catch (IOException e) {
            // Handle exception
        }

    }

    public void send(Object data){
        try{
            out.writeObject( data );
        }
        catch(IOException e){
            // Handle exception
        }       
    }
}

当我连接到服务器时，我的客户端(使用 Swing GUI)创建了该线程的实例。我觉得奇怪的是，我可以从主 GUI 调用方法 send(Object data)，而且它有效。为什么无限 while 循环和/或调用 in.readObject() 不会阻止我这样做？我的意思是线程不应该忙于不断做其他事情吗？这是一个好的做事方式吗？如果没有，为什么不呢？

编辑

为了澄清让我困惑的事情:如果这是在主线程中，它会忙于 in.readObject() 直到读取到某些内容，然后它会再次开始监听循环的下一次迭代。当然，我知道我可以从另一个线程调用 send() 。但令我震惊的是——“谁”实际上在执行 send()？是我的线程在执行此操作，还是调用线程在执行此操作？如果是前者，怎么可能既忙于在 while 循环中等待输入，又忙于执行 send() 方法呢？我只是很难集中注意力......

Answer 1

有两件事:

1) 无限循环不会让 cpu 仅忙于自身。它只是在可用时不断地使其保持忙碌，但其他线程我也使用它。

2) 当您调用您的

send(Object data)

你不是从你的线程中执行此操作，因此请记住1)它被调用没有什么奇怪的

示例:

代码:

public class Main {
    public static void main(String[] args) {
        InfiniteThread t = new InfiniteThread();
        t.start();
        for(int i=0;i<10;i++) {
            t.fromOut(i);
        }
    }
    @DebugLog
    public static class InfiniteThread extends Thread {

        public void run() {
            for(int i=0;i<10;i++) {
                fromIn();
            }
        }

        private void fromIn() {
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }

        public void fromOut(Object data){
            try {
                Thread.sleep(500);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

输出:

InfiniteThread :: ⇢ () [Thread:"main"] InfiniteThread :: ⇠ [0ms] InfiniteThread :: ⇢ run() [Thread:"Thread-0"] InfiniteThread :: ⇢ fromIn() [Thread:"Thread-0"] InfiniteThread :: ⇢ fromOut(data=0) [Thread:"main"] InfiniteThread :: ⇠ fromOut [500ms] InfiniteThread :: ⇢ fromOut(data=1) [Thread:"main"] InfiniteThread :: ⇠ fromIn [1000ms] InfiniteThread :: ⇢ fromIn() [Thread:"Thread-0"] InfiniteThread :: ⇠ fromOut [500ms] InfiniteThread :: ⇢ fromOut(data=2) [Thread:"main"] InfiniteThread :: ⇠ fromOut [500ms] InfiniteThread :: ⇢ fromOut(data=3) [Thread:"main"] InfiniteThread :: ⇠ fromIn [1000ms] InfiniteThread :: ⇢ fromIn() [Thread:"Thread-0"] InfiniteThread :: ⇠ fromOut [500ms] InfiniteThread :: ⇢ fromOut(data=4) [Thread:"main"] InfiniteThread :: ⇠ fromOut [500ms] InfiniteThread :: ⇢ fromOut(data=5) [Thread:"main"] InfiniteThread :: ⇠ fromIn [1000ms] InfiniteThread :: ⇢ fromIn() [Thread:"Thread-0"] InfiniteThread :: ⇠ fromOut [500ms] InfiniteThread :: ⇢ fromOut(data=6) [Thread:"main"] InfiniteThread :: ⇠ fromOut [500ms] InfiniteThread :: ⇢ fromOut(data=7) [Thread:"main"] InfiniteThread :: ⇠ fromIn [1000ms] InfiniteThread :: ⇢ fromIn() [Thread:"Thread-0"] InfiniteThread :: ⇠ fromOut [500ms] InfiniteThread :: ⇢ fromOut(data=8) [Thread:"main"] InfiniteThread :: ⇠ fromOut [500ms] InfiniteThread :: ⇢ fromOut(data=9) [Thread:"main"] InfiniteThread :: ⇠ fromIn [1000ms] InfiniteThread :: ⇢ fromIn() [Thread:"Thread-0"] InfiniteThread :: ⇠ fromOut [500ms] InfiniteThread :: ⇠ fromIn [1000ms] InfiniteThread :: ⇢ fromIn() [Thread:"Thread-0"] InfiniteThread :: ⇠ fromIn [1000ms] InfiniteThread :: ⇢ fromIn() [Thread:"Thread-0"] InfiniteThread :: ⇠ fromIn [1000ms] InfiniteThread :: ⇢ fromIn() [Thread:"Thread-0"] InfiniteThread :: ⇠ fromIn [1000ms] InfiniteThread :: ⇢ fromIn() [Thread:"Thread-0"] InfiniteThread :: ⇠ fromIn [1000ms] InfiniteThread :: ⇠ run [10003ms]