Java 套接字 writeObject 卡住

Question

我正在尝试创建一些本地聊天软件。一切正常，但只停留在一点上；当用户单击按钮时，我的程序会卡住。

我编写了一个修改后的类，它的行为适用于服务器和客户端。

下面是我的代码:

package connections;

import java.awt.event.ActionEvent;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.nio.channels.SocketChannel;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JFrame;
import ui.ChatWindow;

public class Chat{

private SocketChannel socketChannel;
private ConnectionType connectionType;

private ObjectOutputStream out;
private ObjectInputStream in;

private String strClientName;

private ChatWindow chatWindow;
private String strMessage;

public Chat(SocketChannel socketChannel, ConnectionType connectionType) {
    this.socketChannel = socketChannel;
    this.connectionType = connectionType;

    init();
}

private void init() {

    new Thread(this::initThread).start();
}

private void initThread() {
    try {
        out = new ObjectOutputStream(socketChannel.socket().getOutputStream());
        in = new ObjectInputStream(socketChannel.socket().getInputStream());

        if (connectionType == ConnectionType.SERVER) {
            getClientName();
            sendMyName();
        } else {
            sendMyName();
            getClientName();
        }

        chatWindow = new ChatWindow();
        chatWindow.btnSend.addActionListener(this::eventBtnSend);
        chatWindow.setTitle(strClientName);
        chatWindow.setSize(600, 400);
        chatWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        if (connectionType == ConnectionType.CLIENT) {
            chatWindow.setVisible(true);
            chatWindow.requestFocus();
        }

        System.out.println("here");

        beginChat();

        System.out.println("thread ends");

    } catch (IOException ex) {
        Logger.getLogger(Chat.class.getName()).log(Level.SEVERE, null, ex);
    }
}

private void getClientName() {

    try {
        strClientName = (String) in.readObject();
    } catch (IOException | ClassNotFoundException ex) {
        Logger.getLogger(Status.class.getName()).log(Level.SEVERE, null, ex);
    }
}

private void sendMyName() {

    try {
        out.writeObject(main.Config.myName);
        out.flush();
    } catch (IOException ex) {
        Logger.getLogger(Status.class.getName()).log(Level.SEVERE, null, ex);
    }
}

private void beginChat() {
    while (true) {
        try {                
            waitForMessage();
        } catch (IOException | ClassNotFoundException ex) {
            Logger.getLogger(Chat.class.getName()).log(Level.SEVERE, null, ex);
        }
    }
}

private void waitForMessage() throws IOException, ClassNotFoundException {
    System.out.println("waiting for Message : " + connectionType);
    strMessage = (String) in.readObject();
    System.out.println("Message received");
    chatWindow.txtDisplay.append(strClientName + " : " + strMessage + "\n");

    if(chatWindow.isVisible() == false){
        chatWindow.setVisible(true);
    }
}

private void sendMessage(String strMessage) {

    try {
        out.writeObject(strMessage);
        out.flush();
    } catch (IOException ex) {
        Logger.getLogger(Chat.class.getName()).log(Level.SEVERE, null, ex);
    }
}

private void eventBtnSend(ActionEvent ae){
    System.out.println("a");
    sendMessage(chatWindow.txtMessage.getText());
    System.out.println("b");
    chatWindow.txtDisplay.append("Me : " + chatWindow.txtMessage.getText() + "\n");
    System.out.println("c");
    chatWindow.txtMessage.setText("");
}
}

当服务器和客户端连接时，我可以看到以下输出:

here
waiting for Message : SERVER
here
waiting for Message : CLIENT

但是当我单击发送按钮时，我的程序卡住了。单击按钮后我可以看到:

a on console.

Answer 1

这个词是“ block ”。它会阻塞 I/O。它会阻塞。

不要在事件线程上执行阻塞操作。所有网络代码都应该在单独的线程上运行。其中包括 readObject() 和 writeObject()、flush() 以及创建流。