通过套接字发送一个字符串。服务器收不到

Question

我最近一直在努力寻找一种通过套接字文件传递字符串的方法。我打算创建一个远程工具（客户端）来根据收到的消息（服务器）执行操作。我在 google 上搜索了我的问题的答案，我找到了一些东西并设法理解了一些东西，但我也遇到了一些问题（我是编程新手，还没有上大学）。

我将不胜感激在这件事上的任何帮助

SocketService.java ---- class 文件=服务器端

 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 文件=服务器端主包；

import socket.ServiceSocket;

public class Main {

   public static void main(String[] args) {

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

Main.java = 客户

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();

    }
}

主要问题

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

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

                   }
               }while(looprunning);

它没有读取 string/UTF

Answer 1

确实在此处阅读了它：

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

然后将其丢弃，因为您没有将 return-value 分配给变量，然后尝试读取另一个变量，此处：

message = socketMessage.readUTF();

但是您发送的一条（第一条）消息已经消失了。

Answer 2

您在

中遇到问题

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

第一次调用方法 readUTF() 将阻塞线程并从套接字读取 UTF 字符串，但您丢弃该值并尝试第二次读取字符串。

如果您将 socketMessage.readUTF() != null 替换为 looprunning 服务器将记录此消息：

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

P.S。命令无法识别，因为使用 == 比较对象（字符串是对象），但您必须使用 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");
    }

}

服务器日志：

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

通过套接字发送一个字符串。服务器收不到

Sending a String through socket. Server not receiving it

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serversocket