如何在Java中创建请求-响应TCP ​​CProgram？

Question

我正在开发一个Java客户端服务器程序，但是我很难创建一个tcp套接字，该套接字将收到一个又一个的消息，并在发出请求后立即分别响应每个消息。因为（-1）又名在接收套接字字节期间收到的终止分隔符是在套接字关闭之后出现的。

-我想达到的目标是（例如，暗示有圆锥形）
客户>>“请求”
服务器>>“响应”
客户>>“请求”
服务器>>“响应”
...等等

我该如何在JAVA中做到这一点？ 每次发送和接收消息时都必须关闭和打开套接字连接吗？

对不起，没有整齐地解释它！ 先感谢您！！！

Answer 1

MyServer是服务器代码

import java.io.*;  
import java.net.*;  

public class MyServer {  

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

        ServerSocket ss=new ServerSocket(6666);  
        Socket s = ss.accept();//establishes connection    

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        //BufferedWriter dout = new BufferedWriter(new OutputStreamWriter(s.getOutputStream()));
        DataInputStream din = new DataInputStream(s.getInputStream());
        DataOutputStream dout = new DataOutputStream(s.getOutputStream());

        String str1 = "";
        String str2 = "";

        while(!str1.equals("stop")){

        str1 = din.readUTF();;
        System.out.println("Client: " + str1);

        str2 = br.readLine();

        dout.writeUTF(str2);
        dout.flush();

        }

        din.close();
        s.close();
        ss.close();

    }  
}

MyClient是客户端代码

import java.io.*;  
import java.net.*;  

public class MyClient {  

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

        Socket s = new Socket("localhost",6666);  

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        //BufferedReader din = new BufferedReader(new InputStreamReader(s.getInputStream()));
        DataInputStream din = new DataInputStream(s.getInputStream());
        DataOutputStream dout = new DataOutputStream(s.getOutputStream());

        String str1 = "";
        String str2 = "";
        while(!str1.equals("stop")){

        str1 = br.readLine();
        dout.writeUTF(str1);
        dout.flush();

        str2 = din.readUTF();
        System.out.println("Server: " + str2);

        }

        dout.close();
        s.close();  
    }  
} 

此代码允许客户端和服务器之间进行双向通信。 可以通过从任何一侧发送停止消息来停止通信。

并记住从客户端发送第一条消息以开始交流

Answer 2

这是服务器多线程的示例：

服务器.java

import java.net.ServerSocket;
import java.net.Socket;

public class Server implements Runnable{



    private ServerSocket socket = null;
    private Socket sock = null;
    private boolean running = false;

    public Server(){
        try{
            socket = new ServerSocket(4444);
        }catch(Exception e){
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        while(!running){
            running = true;
            System.out.println("Server : UP");
            try{
                sock = socket.accept();
            }catch(Exception e){
                System.out.println("Errore durante l'attesa di nuove connessioni.");
                break;
            }
            ClientThread ct = new ClientThread(sock,this);
            Thread t = new Thread(ct);
            t.start();

            System.out.println("In attesa di connessioni...");

        }

    }

    public void stop(){
        if(running){
            running = false;
            System.out.println("Server : DOWN");
            try{
                socket.close();
            }catch(Exception e){
                e.printStackTrace();
                return;
            }
        }   
    }

    public boolean isRunning(){
        return running;
    }

}

ClientThread.java

package Server;

import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.NoSuchElementException;
import java.util.Scanner;

public class ClientThread implements Runnable{

    private Scanner scan;
    private PrintWriter pw;
    private Socket sock;
    private Server main_thread;
    private boolean flag = false;
    private boolean running = true;
    private SenderThread st = null;

    public ClientThread(Socket sock,Server server){
        this.sock = sock;
        this.main_thread = server;

    }

    @Override
    public void run() {
        if(flag)
            return;
        flag = true;
        try{
            scan = new Scanner(sock.getInputStream());
            pw = new PrintWriter(sock.getOutputStream());
        }catch(Exception e){
            e.printStackTrace();
        }

        while(running){
          try{
            String cmd = scan.nextLine();
            if(cmd.equals("Start")){
                st = new SenderThread(pw);
                Thread t = new Thread(st);
                t.start();
            }
            else if(cmd.equals("Stop")){
                st.stop();
            }
            else{
                running = false;
            }
          }catch(NoSuchElementException e){
              running = false;
              e.printStackTrace();
          }
        }

        try{
            sock.close();
            scan.close();
            pw.close();
        }catch(Exception e){
            e.printStackTrace();
        }

    }

}

侦听器

package Client;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.ObjectOutputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;

import javax.swing.JOptionPane;

public class Listener implements ActionListener{

    private GuiClient frame;
    private Socket socket;
    private Scanner scan;
    private PrintWriter pw;
    private Receiver receiver = null;

    public Listener(GuiClient gui){
        this.frame = gui;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        String cmd = e.getActionCommand();
        if(cmd.equals("Connect")){
            if(frame.ip_textfield.getText() == "" || frame.port_textfield.getText() == "" ){
                JOptionPane.showMessageDialog(null, "Dati insufficienti !!!");
            }
            String address = frame.ip_textfield.getText();
            int port = Integer.parseInt(frame.port_textfield.getText());
            try{
                setupConnection(address,port);
                frame.status_label.setText("SERVER UP");
            }catch(Exception e1){
                JOptionPane.showMessageDialog(null, "Impossibile stabilire una connessione con il server.");
                e1.printStackTrace();
            }
            frame.Start.setEnabled(true);
            frame.Connect.setEnabled(false);
            frame.Disconnect.setEnabled(true);
            frame.Stop.setEnabled(false);
        }else if(cmd.equals("Start")){
            //ricevi stringhe e mostrale a schermo
            frame.Start.setEnabled(false);
            frame.Stop.setEnabled(true);
            frame.Connect.setEnabled(false);
            frame.Disconnect.setEnabled(false);
            pw.println(cmd);
            pw.flush();
            try{
              receiver = new Receiver(frame.status_label,scan);
            }catch(Exception e2){
                JOptionPane.showMessageDialog(null, "Impossibile ricevere stringhe...");
                e2.printStackTrace();
            }
            System.out.println("Client : "+cmd);
            Thread t = new Thread(receiver);
            t.start();
        }else if(cmd.equals("Stop")){
            frame.Stop.setEnabled(false);
            frame.Disconnect.setEnabled(true);
            frame.Connect.setEnabled(false);
            frame.Start.setEnabled(true);
            try{
                pw.println(cmd);
                pw.flush();
                JOptionPane.showMessageDialog(null, "Ricezione delle stringhe interrotta.");
            }catch(Exception e1){
                e1.printStackTrace();
            }
        }else if(cmd.equals("Disconnect")){
            frame.Connect.setEnabled(true);
            frame.Disconnect.setEnabled(false);
            frame.Start.setEnabled(false);
            frame.Stop.setEnabled(false);
            try{
                socket.close();
            }catch(Exception e1){
                e1.printStackTrace();
            }
        }

    }

    private void setupConnection(String address, int port){
        try{
            socket = new Socket(address,port);
            OutputStream os = socket.getOutputStream();
            scan = new Scanner(socket.getInputStream());
            pw = new PrintWriter(os);
        }catch(Exception e){
            e.printStackTrace();
        }
    }

}

侦听器在gui客户端后面工作; SenderThread和Receiver是可与字符串一起使用的其他Java类（在这种情况下），希望对您有所帮助。