通过套接字发送字符串。 服务器未收到

Question

I've been struggling lately to find a way to deliver strings through a socket file. I'm planning to create a remote tool(client) to execute things based on the received message(server). I've searched answers for my problem on google and i found some things and managed to understand things but I also got some problems (i'm new to programming, not yet in college).

I would appreciate any help in this matter

SocketService.java ---- class file = serverside

 package socket;

import java.io.DataInputStream;
import java.io.EOFException;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.concurrent.TimeUnit;

public class ServiceSocket {
    static ServerSocket myService;
    static Socket thesocket;
    static Thread socketThread;
    public static boolean socketRunning;
     public static DataInputStream socketMessage;


    public static void initialise(String localhost, int portNumber ){
        // make a server socket//////
        try {
            myService = new ServerSocket(portNumber);
            System.out.println();
        } catch (IOException e) {
            e.printStackTrace();
        }
        //////////////////////////////

    }

    public static void deploySocket(){
        socketThread = new Thread() {
            public void run(){

                // making connection
                System.out.println("VVaiting for connection...");
                try {
                    thesocket = myService.accept();
                    System.out.println("Connection made");
                    socketRunning = true;
                } catch (IOException e) {
                    e.printStackTrace();
                }
                ////////////////////////////////////
                try {
                    StartBrain();
                } catch (IOException e1) {
                    e1.printStackTrace();
                }

                if(socketRunning = false) {
                try {
                    thesocket.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
      }

    };
        socketThread.start();
  }

     public static String getSocketMessage() throws IOException {

         try {
            socketMessage = new DataInputStream(thesocket.getInputStream());
        } catch (IOException e1) {
            e1.printStackTrace();
        }
         boolean looprunning = true;
         String message = null;
         System.out.println("entering loop");
               do {
                   try {
                   while (socketMessage.readUTF() != null) {

                message = socketMessage.readUTF();
                looprunning = false;
                      }
                   } catch (EOFException e) {

                   }
               }while(looprunning);

                System.out.println("Message received from UTF: " + message);
                System.out.println("loop exited vvith message");   

         if(message == null) {
          message = "no message";
         }

         return message;
     }

     public static void StartBrain() throws IOException {
         System.out.println("socket brain started");
        String BrainMessage = getSocketMessage();
             if(BrainMessage == "command") {
                 System.out.println("Command EXECUTED HAHA");
             } else if(BrainMessage == "taskschedule") {
                 System.out.println("task scheduled");
             } else {
                 System.out.println("no command received");
             }

         }

Main.java ----- class file = serverside package main;

import socket.ServiceSocket;

public class Main {

   public static void main(String[] args) {

      ServiceSocket.initialise("localhost", 3535);
      ServiceSocket.deploySocket();
    }
   }  
} 

Main.java = CLIENT

package mainPackage;

import java.io.*;
import java.net.*;
import java.util.concurrent.TimeUnit;

public class Main {
    private static Socket clientSocket;

    public static void sendMessage(String message) throws IOException, InterruptedException {
        DataOutputStream dOut = new DataOutputStream(Main.clientSocket.getOutputStream());

        dOut.writeUTF(message);
        dOut.flush(); 

        dOut.close();
            }

    public static void main(String[] args) throws Exception {
     //   String modifiedSentence;

        clientSocket = new Socket("localhost", 3535);
        System.out.println("Initializing");
        sendMessage("command");

        boolean running = true;
     while(running) {
         TimeUnit.SECONDS.sleep(3);
         sendMessage("taskschedule");
     }
     clientSocket.close();

    }
}

main problem

 do {
                   try {
                   while (socketMessage.readUTF() != null) {

                message = socketMessage.readUTF();
                looprunning = false;
                      }
                   } catch (EOFException e) {

                   }
               }while(looprunning);

it doesn't read the string/UTF

Answer 1

It does read it, here:

while (socketMessage.readUTF() != null) {

and then throws it away as you're not assigning the return-value to a variable, and then tries to read another one, here:

message = socketMessage.readUTF();

but the one (first) message you send is already gone.

Answer 2

You have problem in

while (socketMessage.readUTF() != null) {
    message = socketMessage.readUTF();
    looprunning = false;
}

First call to method readUTF() will block thread and read UTF string from socket, but you discard this value and try read string second time.

If you replace socketMessage.readUTF() != null with looprunning server will log this messages:

VVaiting for connection...
Connection made
socket brain started
entering loop
Message received from UTF: command
loop exited vvith message
no command received

PS Command is not recognized because use compare objects (string is object) with == , but you must use equals .

public static void StartBrain() throws IOException {
    System.out.println("socket brain started");
    String BrainMessage = getSocketMessage();
    if (BrainMessage.equals("command")) {
        System.out.println("Command EXECUTED HAHA");
    } else if (BrainMessage.equals("taskschedule")) {
        System.out.println("task scheduled");
    } else {
        System.out.println("no command received");
    }

}

Server log:

VVaiting for connection...
Connection made
socket brain started
entering loop
Message received from UTF: command
loop exited vvith message
Command EXECUTED HAHA