Linux环境下Java如何进行网络编程

在Linux环境下进行Java网络编程，主要涉及到使用Java的网络库，如java.net包中的类和接口。以下是一些基本步骤和示例代码，帮助你在Linux环境下进行Java网络编程。

1. 创建一个简单的TCP服务器

服务器端代码

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

public class TCPServer {
    public static void main(String[] args) {
        int port = 12345; // 服务器监听的端口

        try (ServerSocket serverSocket = new ServerSocket(port)) {
            System.out.println("服务器已启动，正在监听端口 " + port);

            while (true) {
                Socket clientSocket = serverSocket.accept();
                System.out.println("新客户端连接: " + clientSocket.getInetAddress().getHostAddress());

                // 处理客户端请求
                BufferedReader in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
                PrintWriter out = new PrintWriter(clientSocket.getOutputStream(), true);

                String inputLine;
                while ((inputLine = in.readLine()) != null) {
                    System.out.println("收到客户端消息: " + inputLine);
                    out.println("服务器已收到: " + inputLine);
                }

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

客户端代码

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

public class TCPClient {
    public static void main(String[] args) {
        String hostname = "localhost"; // 服务器地址
        int port = 12345; // 服务器监听的端口

        try (Socket socket = new Socket(hostname, port)) {
            System.out.println("已连接到服务器 " + hostname + ":" + port);

            BufferedReader userInput = new BufferedReader(new InputStreamReader(System.in));
            PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));

            String userInputLine;
            while ((userInputLine = userInput.readLine()) != null) {
                out.println(userInputLine);
                System.out.println("服务器回复: " + in.readLine());
            }
        } catch (UnknownHostException e) {
            System.err.println("未知主机: " + hostname);
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

2. 创建一个简单的UDP服务器

服务器端代码

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

public class UDPServer {
    public static void main(String[] args) {
        int port = 12345; // 服务器监听的端口

        try (DatagramSocket socket = new DatagramSocket(port)) {
            System.out.println("UDP服务器已启动，正在监听端口 " + port);

            byte[] buffer = new byte[1024];
            DatagramPacket packet = new DatagramPacket(buffer, buffer.length);

            while (true) {
                socket.receive(packet);
                String received = new String(packet.getData(), 0, packet.getLength());
                System.out.println("收到客户端消息: " + received);

                // 发送回复
                String reply = "服务器已收到: " + received;
                DatagramPacket replyPacket = new DatagramPacket(reply.getBytes(), reply.length(), packet.getAddress(), packet.getPort());
                socket.send(replyPacket);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

客户端代码

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

public class UDPClient {
    public static void main(String[] args) {
        String hostname = "localhost"; // 服务器地址
        int port = 12345; // 服务器监听的端口

        try (DatagramSocket socket = new DatagramSocket()) {
            InetAddress address = InetAddress.getByName(hostname);

            BufferedReader userInput = new BufferedReader(new InputStreamReader(System.in));
            String userInputLine;
            while ((userInputLine = userInput.readLine()) != null) {
                byte[] buffer = userInputLine.getBytes();
                DatagramPacket packet = new DatagramPacket(buffer, buffer.length, address, port);
                socket.send(packet);

                byte[] replyBuffer = new byte[1024];
                DatagramPacket replyPacket = new DatagramPacket(replyBuffer, replyBuffer.length);
                socket.receive(replyPacket);
                String received = new String(replyPacket.getData(), 0, replyPacket.getLength());
                System.out.println("服务器回复: " + received);
            }
        } catch (UnknownHostException e) {
            System.err.println("未知主机: " + hostname);
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

3. 运行程序

1. 在Linux终端中编译Java代码：

   javac TCPServer.java
   javac TCPClient.java
   

2. 启动服务器：

   java TCPServer
   

3. 在另一个终端中启动客户端：

   java TCPClient
   

对于UDP服务器和客户端，步骤类似：

1. 编译：

   javac UDPServer.java
   javac UDPClient.java
   

2. 启动UDP服务器：

   java UDPServer
   

3. 在另一个终端中启动UDP客户端：

   java UDPClient
   

通过这些步骤，你可以在Linux环境下进行基本的Java网络编程。根据需求，你可以进一步扩展和优化这些示例代码。