Java网络服务端与客户端如何通信

在Java中，有多种方法可以实现网络服务端与客户端之间的通信。这里，我将向您介绍两种常用的方法：使用Socket和使用ServerSocket与Socket。

1. 使用Socket和ServerSocket进行通信：

服务器端（ServerSocket）：

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

public class Server {
    public static void main(String[] args) {
        int port = 12345;
        try {
            ServerSocket serverSocket = new ServerSocket(port);
            System.out.println("Server is listening on port " + port);

            Socket socket = serverSocket.accept();
            System.out.println("Client connected");

            InputStream inputStream = socket.getInputStream();
            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
            String message = reader.readLine();
            System.out.println("Received message: " + message);

            OutputStream outputStream = socket.getOutputStream();
            PrintWriter writer = new PrintWriter(outputStream, true);
            writer.println("Message received by server");

            socket.close();
            serverSocket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

客户端（Socket）：

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

public class Client {
    public static void main(String[] args) {
        String serverAddress = "localhost";
        int port = 12345;

        try {
            Socket socket = new Socket(serverAddress, port);
            System.out.println("Connected to server");

            OutputStream outputStream = socket.getOutputStream();
            PrintWriter writer = new PrintWriter(outputStream, true);
            writer.println("Hello, server!");

            InputStream inputStream = socket.getInputStream();
            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
            String message = reader.readLine();
            System.out.println("Received message from server: " + message);

            socket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

2. 使用HttpURLConnection进行通信（适用于HTTP协议）：

服务器端（Server）：

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

public class HttpServer {
    public static void main(String[] args) {
        int port = 8080;
        try {
            ServerSocket serverSocket = new ServerSocket(port);
            System.out.println("Server is listening on port " + port);

            Socket socket = serverSocket.accept();
            System.out.println("Client connected");

            InputStream inputStream = socket.getInputStream();
            BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
            String requestLine = reader.readLine();
            System.out.println("Received request: " + requestLine);

            OutputStream outputStream = socket.getOutputStream();
            PrintWriter writer = new PrintWriter(outputStream, true);
            writer.println("HTTP/1.1 200 OK");
            writer.println("Content-Type: text/plain");
            writer.println("Content-Length: 13");
            writer.println();
            writer.println("Hello, client!");

            socket.close();
            serverSocket.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

客户端（Socket）：

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

public class HttpClient {
    public static void main(String[] args) {
        String serverAddress = "localhost";
        int port = 8080;

        try {
            URL url = new URL("http://" + serverAddress + ":" + port);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setRequestMethod("GET");
            connection.setConnectTimeout(5000);
            connection.setReadTimeout(5000);

            int responseCode = connection.getResponseCode();
            System.out.println("Response code: " + responseCode);

            if (responseCode == HttpURLConnection.HTTP_OK) {
                InputStream inputStream = connection.getInputStream();
                BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
                String line;
                StringBuilder response = new StringBuilder();

                while ((line = reader.readLine()) != null) {
                    response.append(line);
                }
                System.out.println("Received message from server: " + response.toString());
            } else {
                System.out.println("GET request failed");
            }

            connection.disconnect();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

以上示例展示了如何使用Java的Socket和ServerSocket进行通信，以及如何使用HttpURLConnection进行HTTP协议通信。您可以根据自己的需求选择合适的方法。