java套接字客户端发送到服务器，但无法听

Question

我必须做一个非常简单的TCP服务器，它使用TCP监听某个客户端并以大写形式返回消息。

连接stablishes精致，完美的客户发送消息和服务器监听到他们，但服务器将不回答，我没有的为什么会这样一个线索...

服务器：

//imports and stuff you don't really care about 

public class ServerThread extends Thread { 

private final Socket clientSocket; 
private final Main controller; 
private final Server server; 

BufferedReader in; 
PrintWriter out; 

//constructor 
ServerThread(Socket clientSocket, Main controller, Server server) throws IOException { 
    this.clientSocket = clientSocket; 
    this.controller = controller; 
    this.server = server; 
    //make input and output streams 
    in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream())); 

    //THIS MAY BE WRONG 
    out = new PrintWriter(clientSocket.getOutputStream()); 
} 

@Override 
public void run() { 

    controller.out("Connected: " + clientSocket.getInetAddress().toString()); 
    out.println("test"); 
    try { 
     String msg; 
     while ((msg = in.readLine()) != null) { 
      //Prints this line 
      System.out.println(clientSocket.getInetAddress().toString() + " says: " + msg); 
      //THIS MAY BE WRONG 
      out.println(msg.toUpperCase()); 

      System.out.println("Answered");//this line too 
     } 
    }catch(SocketException ex){ 
     destroyMe(); 
    } 
    catch (IOException ex) { 
     Logger.getLogger(ServerThread.class.getName()).log(Level.SEVERE, null, ex); 
     destroyMe(); 
    } 
} 

//couple of methods that don't interfere here 
} 

客户：

public class Client extends Thread { 

private final String host = "localhost"; 
private final int port = 44444; 
private final PrintWriter out; 
private final Socket socket; 
BufferedReader in; 

private Main c; 

public Client(Main c) throws IOException { 
    this.c = c; 

    socket = new Socket(host, port); 
    out = new PrintWriter(socket.getOutputStream(), true); 
    in = new BufferedReader(new InputStreamReader(socket.getInputStream())); 

    System.out.println("Connection Opened."); 
} 

public void send(String str) { 
    out.println(str); //this works fine 
} 

@Override 
public void run() { 
    String msg; 
    while (true) { 
     try { 
      //THIS MAY BE WRONG but I don't think so 
      while ((msg = in.readLine()) != null) { 
       System.out.println("received: " + msg); //this never happens 
       c.out(msg); 
      } 
      //this line is always reached until I close the connection. 
     } catch (SocketException ex) { 
      System.out.println("Connection closed"); //this line is reached too 
      break; 
     } catch (IOException ex) { 
      Logger.getLogger(Client.class.getName()).log(Level.SEVERE, null, ex); 
      //This works fine 
     } 
    } 
}//end of the thread 

//there are a couple of methods here but they don't do anything related 
} 

我看不出有什么错，但一定有东西。

感谢您的帮助。

Answer 1

您正在使用PrinterWriter来控制您的服务器代码的输出。

通过out = new PrintWriter(clientSocket.getOutputStream());打开自动冲洗功能时未通过打开自动冲洗功能通过println，printf或格式方法编写消息时，会在按文档打开时自动冲洗。

打开自动冲水&使用上述方法为你写消息，当你想发送消息时调用flush方法，或者完全使用不同的方法来控制你的服务器输出流。

http://docs.oracle.com/javase/7/docs/api/java/io/PrintWriter.html