TCP 服务器未从 TCP 客户端接收消息 (Java)

Question

服务器似乎没有收到客户端发送的消息。据我了解，客户端正在写入套接字输出流。服务器正在从套接字输入流中读取。请帮忙。

服务器代码：

import java.io.*;
import java.net.ServerSocket;
import java.net.Socket;

public class TCPServer {
static final int DEFAULT_PORTNUMBER = 1236;

public static void main(String[] args){
    int portnumber;

    if(args.length >= 1){
        portnumber = Integer.parseInt(args[0]);
    }else{
        portnumber = DEFAULT_PORTNUMBER;
    }

    //Setting a server socket and a possible client socket
    ServerSocket server = null;
    Socket client;

    try{
        server = new ServerSocket(portnumber);
    } catch (IOException e){
        e.printStackTrace();
    }
    while(true){

        try{
            System.out.println("Waiting for client...");
            client = server.accept();
            System.out.println("Client accepted... ");
            //Read data form the client
            BufferedReader br = new BufferedReader(new InputStreamReader(client.getInputStream()));

            while(!br.ready()){
                System.out.println("No message from client");
            }
            String msgFromClient = br.readLine();
            //System.out.println("Message received from client = " + msgFromClient);

            //Send Response
            if(msgFromClient != null && !msgFromClient.equalsIgnoreCase("bye")){
                OutputStream clientOut = client.getOutputStream();
                PrintWriter pw = new PrintWriter(clientOut, true);
                String ansMsg = "Hello, " + msgFromClient;
                pw.println(ansMsg);
            }

            if(msgFromClient != null && msgFromClient.equalsIgnoreCase("Bye")){
                server.close();
                client.close();
                break;
            }
        } catch(IOException e) {
            e.printStackTrace();
        }
        //New thread for client
        /*new ServerThread(client).start();
        System.out.println("Client connection accepted... ");*/
    }

}
}

客户代码：

import java.io.*;
import java.net.InetAddress;
import java.net.Socket;


public class TCPClient {
static final int DEFAULT_PORTNUMBER = 1236;
public static void main(String args[]){
    Socket client = null;
    int portnumber;

    //Default port number if not specified as an argument

    if(args.length >= 1){
        portnumber = Integer.parseInt(args[0]);
    }else{
        portnumber = DEFAULT_PORTNUMBER;
    }


    try {
        String msg = "";

        //Creating a client socket
        client = new Socket(InetAddress.getLocalHost(), portnumber);
        System.out.println("Client socket is created: " + client);

        //Creating an output stream for the client socket
        OutputStream clientOUt = client.getOutputStream();
        PrintWriter pw = new PrintWriter(clientOUt, true);

        //Creating an input stream for the client socket
        InputStream clientIn = client.getInputStream();
        BufferedReader br = new BufferedReader(new InputStreamReader(clientIn));

        //Creating a buffered reader for standard input System.in
        BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));

        System.out.println("Enter your name. Type Bye to exit.");

        //Read data from standard input and write to output stream
        msg = stdIn.readLine().trim();
        pw.print(msg);

        while(!br.ready()){
            //System.out.println("No Input From Server");
        }
        //Read data from input stream of client socket
        System.out.println("Message returned from the server = " + br.readLine());

        pw.close();
        br.close();
        client.close();

        //Stop operation
        if (msg.equalsIgnoreCase("Bye")) {
            System.exit(0);
        } else {
        }

    } catch (IOException e) {
        System.out.println("I/O error " + e);
    }



}
}

注意：我确实禁用了防火墙，但这没有帮助。

Answer 1

找到答案PrintWriter or any other output stream in Java do not know "\r\n"。它描述了 printwriter 如何无法使用 printwriter.print() 正确刷新，而是仅在您使用 printwriter.println() 时才有效。

TCP 服务器未从 TCP 客户端接收消息 (Java)

TCP Server Not Receiving Message From TCP Client (Java)

sockets

client

tcp

serversocket

server