服务器、客户端套接字实现

Question

正在编写一个服务器，使用Java套接字的客户端聊天程序。这是我的服务器套接字类的代码。

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

public class Main {

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

        ServerSocket serverSocket = null;
        try {
            serverSocket = new ServerSocket(8085);
        } catch (IOException ex) {
            System.out.println("IO Error, " + ex);
            System.exit(1);
        }
        Socket clientSocket = null;
        System.out.println("Listening for incoming connections");
        try {
            clientSocket = serverSocket.accept();
        } catch (IOException ex) {
            System.out.println("Failed to accept connection " + ex);
            System.exit(1);
        }
        System.out.println("Connection Successful");
        System.out.println("Listening to get input");
        PrintStream output = new PrintStream(clientSocket.getOutputStream(), true);
        BufferedReader input = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
        String inputLine;
        while ((inputLine = input.readLine()) != null) {
            System.out.println(inputLine);
            System.out.println("Server: ");
            inputLine = input.readLine();
            output.println(inputLine);
            if (!inputLine.equals("exit")) {

            } else {
                break;
            }
        }
        output.close();
        input.close();
        clientSocket.close();
        serverSocket.close();
    }
}

客户端能够建立连接并向服务器发送消息。服务器也可以接收客户端发送的消息。问题是当消息从服务器发送时，客户端没有收到消息。这是我的客户端套接字代码。

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.net.Socket;


public class Client {
public static void main(String [] args) throws Exception
{
    BufferedReader input;
    PrintStream output;
    BufferedReader clientInput;
    try (Socket client = new Socket("127.0.0.1", 8085)) {
        input = new BufferedReader(new InputStreamReader(client.getInputStream()));
        output = new PrintStream(client.getOutputStream());
        clientInput = new BufferedReader(new InputStreamReader(System.in));
        String line;
        while(true)
        {
            System.out.println("Client: ");
            line = clientInput.readLine();
            output.println("Server: " + line );
            if(line.equals("quit"))
            {
                break;
            }
        }
    }
    input.close();
    clientInput.close();
    output.close();
}
}

Answer 1

服务器期望客户端在此处输入额外的一行：

while ((inputLine = input.readLine()) != null) {
    System.out.println(inputLine);
    System.out.println("Server: ");
    inputLine = input.readLine(); // <--- here

客户端没有从连接到服务器时获得的称为输入的输入流中读取。它只是从clientInput读取本地控制台输入。

在Client.java的while循环中，您需要在quit块之后使用类似这样的代码来获得服务器的响应:

System.out.println("Server: " + input.readLine());

Answer 2

当您完成输出流时，刷新它们总是一个好主意，您发送的信息可能已经缓冲。

Answer 3

服务器端:

public class Server {

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

        ServerSocket serverSocket = null;
        try {
            serverSocket = new ServerSocket(8085);
        } catch (IOException ex) {
            System.out.println("IO Error, " + ex);
            System.exit(1);
        }
        Socket clientSocket = null;
        System.out.println("Listening for incoming connections");
        try {
            clientSocket = serverSocket.accept();
        } catch (IOException ex) {
            System.out.println("Failed to accept connection " + ex);
            System.exit(1);
        }
        System.out.println("Connection Successful");
        System.out.println("Listening to get input");
        PrintStream output = new PrintStream(clientSocket.getOutputStream(), true);
        BufferedReader input = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
        String inputLine;
        while ((inputLine = input.readLine()) != null) {

            System.out.println("Client request: " + inputLine);

            String resp = "some response as you need";
            output.println(resp);
            System.out.println("Server response: " + resp);

            if (!inputLine.equals("exit")) {

            } else {
                break;
            }
        }
        output.close();
        input.close();
        clientSocket.close();
        serverSocket.close();
    }
}

客户端:

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintStream;
import java.net.Socket;

public class Client {

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

        BufferedReader input;
        PrintStream output;
        BufferedReader clientInput;
        try (Socket client = new Socket("127.0.0.1", 8085)) {
            input = new BufferedReader(new InputStreamReader(client.getInputStream()));
            output = new PrintStream(client.getOutputStream());
            clientInput = new BufferedReader(new InputStreamReader(System.in));

            while (true) {

                String inputStr = clientInput.readLine();

                output.println(inputStr);
                System.out.println("Client: " + inputStr);

                if (inputStr.equals("quit")) {
                    break;
                }

                String serverResp = input.readLine();
                output.println("Server: " + serverResp);
            }
        }
    }
}

这是经过测试的。