Java线程程序停止运行，没有错误消息（mac终端/命令提示符）

时间：2017-04-07 00:27:22

标签： java eclipse multithreading

这个程序的目的是在客户端和服务器之间发送文本消息（字符串）（使用java线程），就像两个手机会相互发送文本消息一样。

如果命令行参数中存在“-l”，则它将运行服务器线程。如果命令行参数中不存在“-l”，那么它将运行客户端线程。

在下面的屏幕截图中，左侧窗口是服务器，右侧是客户端。

enter image description here

屏幕截图的问题是左窗口（服务器）应该输出“从客户端收到消息：Hello”，然后继续输出“标准输入（按完成后输入然后控制D）：”

我使用“ok1，ok2，ok3，ok4”作为调试目的的标准输出（你会发现它在代码中停止了哪些行）“所以它可以在将来被删除。

有三个文件：主要功能文件，服务器文件，客户端文件。

服务器代码（DirectMessengerServer.java）：

import java.io.*;
import java.net.*;
import java.util.*;
//import static java.nio.charset.StandardCharsets.*;
public class DirectMessengerServer
{
    private static Socket socket;
    boolean KeepRunning = true;
    void ServerRun(String[] args)
    {
        Thread Server = new Thread () 
        {
            public void run ()
            {   
                System.out.println("Server thread is now running");
                try
                {
                    System.out.println("Try block begins..");
                    int port_number1= Integer.valueOf(args[1]);
                    System.out.println("Port number is: " + port_number1);
                    ServerSocket serverSocket = new ServerSocket(port_number1);
                    //SocketAddress addr = new InetSocketAddress(address, port_number1);
                    System.out.println("Listening for connections..");
                    System.out.println( "Listening on port: " + ( port_number1 ) );

                    while(KeepRunning)
                    {
                        System.out.println("While loop run");
                        //Reading the message from the client

                        socket = serverSocket.accept();    
                        System.out.println("ok1");
                        InputStream is = socket.getInputStream();
                        System.out.println("ok2");
                        InputStreamReader isr = new InputStreamReader(is);
                        System.out.println("ok3");
                        BufferedReader br = new BufferedReader(isr);
                        System.out.println("ok4");
                        String MessageFromClient = br.readLine();
                        System.out.println("ok5");
                        System.out.println("Message received from client: "+ MessageFromClient);


                        //creating message to server send from standard input
                        String newmessage = "";
                        try {
                            // input the message from standard input
                            BufferedReader input= new BufferedReader( 
                              new InputStreamReader(System.in));
                            String line = "";

                            System.out.println( "Standard input (press enter then control D when finished): " );

                            while( (line= input.readLine()) != null && KeepRunning==true )      
                            {
                                newmessage += line + " \n ";
                            }
                            }
                        catch ( Exception e ) {
                            System.out.println( e.getMessage() );
                        }




                        //Writing return message back to client
                        String returnMessage = newmessage;
                        OutputStream os = socket.getOutputStream();
                        OutputStreamWriter osw = new OutputStreamWriter(os);
                        BufferedWriter bw = new BufferedWriter(osw);
                        bw.write(returnMessage);
                        System.out.println("Message sent to client: "+returnMessage);
                        bw.flush();
                        //shutdown with zero-length message
                        if(MessageFromClient.equals("") || MessageFromClient.equals(null) || returnMessage.equals(""))
                        {
                            KeepRunning=false;
                            System.out.println("Shutting down");
                            System.exit(0);
                            socket.close();
                            serverSocket.close();
                        }



                    }
                }
                catch ( Exception e )
                {
                    e.printStackTrace();

                }  
                finally
                {
                    //Closing the socket
                    try
                    {
                        socket.close();


                    }
                    catch(Exception e)
                    {
                        e.printStackTrace();
                    }
                }

            }

        };
        Server.start();
    }
}

客户代码（DirectMessengerClient.java）：

import java.io.*;
import java.net.*;
import java.util.*;
import static java.nio.charset.StandardCharsets.*;
public class DirectMessengerClient
{
    boolean KeepRunning = true;
    private static Socket socket;
    //static String[] arguments;
    //public static void main(String[] args)
    //{
    //  arguments = args;
    //}
    public DirectMessengerClient()
    {

        //System.out.println("test.");

    }
    public void ClientRun(String[] args)
    {
        Thread Client = new Thread ()
        {
          public void run()
          {   
                System.out.println("Client thread is now running");

                    try
                    {
                            System.out.println("Try block begins..");
                            String port_number1= args[0];
                            System.out.println("Port number is: " + port_number1);
                            int port = Integer.valueOf(port_number1);
                            System.out.println("Listening for connections..");
                            System.out.println( "Listening on port: " + port_number1 );

                            while(KeepRunning)
                            {
                                String host = "localhost";
                                InetAddress address = InetAddress.getByName(host);
                                socket = new Socket(address, port);


                                //Send the message to the server
                                OutputStream os = socket.getOutputStream();
                                OutputStreamWriter osw = new OutputStreamWriter(os);
                                BufferedWriter bw = new BufferedWriter(osw);

                                //creating message to send from standard input
                                String newmessage = "";
                                try 
                                {
                                    // input the message from standard input
                                    BufferedReader input= new BufferedReader( 
                                    new InputStreamReader(System.in));
                                    String line = "";

                                    System.out.println( "Standard input (press enter then control D when finished): " );

                                    while( (line= input.readLine()) != null )       
                                    {
                                        newmessage += line + " ";
                                    }
                                }
                                catch ( Exception e )
                                {
                                    System.out.println( e.getMessage() );
                                }
                                String sendMessage = newmessage;
                                bw.flush();
                                System.out.println("Message sent to server: "+sendMessage);

                                //Get the return message from the server
                                InputStream is = socket.getInputStream();
                                InputStreamReader isr = new InputStreamReader(is);
                                BufferedReader br = new BufferedReader(isr);
                                String messageFromServer = br.readLine();
                                System.out.println("Message received from server: " + messageFromServer);

                            }
                }

                catch ( Exception e )
                {
                    e.printStackTrace();
                }

                finally
                {
                    //Closing the socket
                    try
                    {
                        socket.close();
                    }
                    catch(Exception e)
                    {
                        e.printStackTrace();
                    }
                }

          }
        };

    Client.start(); 
    }
}

主要代码（DirectMessengerCombined.java）：

public class DirectMessengerCombined
{
    public static void main(String[] args)
    {
        DirectMessengerClient Client1 = new DirectMessengerClient();
        DirectMessengerServer Server1 = new DirectMessengerServer();
          for (int i = 0; i < args.length; i++)
          {
                if(!args[0].equals("-l"))
                {
                    Client1.ClientRun(args);
                }
                switch (args[0].charAt(0))
                {
                    case '-':
                    if(args[0].equals("-l"))
                    {   
                        Server1.ServerRun(args);
                    }

                }
           i=args.length + 20;
          } 
    }

}

我的问题是：为什么程序在输出ok4的行（服务器窗口）停止运行？没有错误消息，所以我也想知道如果我以某种方式错过它，如何找到错误消息？

1 个答案:

答案 0 :(得分：0)

在DirectMessengerClient课程中，您永远不会将消息发送到服务器。在代码中添加一行来执行此操作：

String sendMessage = newmessage;
bw.write(sendMessage + "\n"); // <--- ADD THIS LINE
bw.flush();
System.out.println("Message sent to server: "+sendMessage);

另请注意，在服务器类中，您正在发送返回消息。但是对BufferedWriter.write的调用不会在消息末尾添加换行符（与System.out.println不同），因此如果您希望能够使用{{1}读取行，则需要自己添加换行符。 }}：

BufferedReader.readLine
相关问题
最新问题