如何在java主方法中使用Socket编程

在Java主方法中使用Socket编程，你需要遵循以下步骤：

1. 导入所需的库：

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

2. 创建一个ServerSocket对象，监听一个端口：

int port = 12345; // 你可以选择任何可用的端口号
ServerSocket serverSocket = new ServerSocket(port);
System.out.println("Server is listening on port " + port);

3. 使用accept()方法接受客户端的连接请求：

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

4. 创建一个OutputStream对象，用于向客户端发送数据：

OutputStream outputStream = socket.getOutputStream();

5. 创建一个InputStream对象，用于从客户端接收数据：

InputStream inputStream = socket.getInputStream();

6. 使用BufferedReader和InputStreamReader读取客户端发送的数据：

BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
String message;
while ((message = bufferedReader.readLine()) != null) {
    System.out.println("Received from client: " + message);
}

7. 使用PrintWriter对象向客户端发送数据：

PrintWriter printWriter = new PrintWriter(outputStream, true);
printWriter.println("Hello from server!");

8. 关闭资源：

bufferedReader.close();
printWriter.close();
socket.close();
serverSocket.close();

将以上代码整合到Java主方法中，完整的示例如下：

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

public class SocketServer {
    public static void main(String[] args) {
        int port = 12345; // 你可以选择任何可用的端口号
        ServerSocket serverSocket = new ServerSocket(port);
        System.out.println("Server is listening on port " + port);

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

            OutputStream outputStream = socket.getOutputStream();
            PrintWriter printWriter = new PrintWriter(outputStream, true);

            InputStream inputStream = socket.getInputStream();
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));

            String message;
            while ((message = bufferedReader.readLine()) != null) {
                System.out.println("Received from client: " + message);
            }

            printWriter.println("Hello from server!");

            bufferedReader.close();
            printWriter.close();
            socket.close();
        } catch (IOException e) {
            System.out.println("Error: " + e.getMessage());
        } finally {
            try {
                serverSocket.close();
            } catch (IOException e) {
                System.out.println("Error: " + e.getMessage());
            }
        }
    }
}

运行此程序后，服务器将监听端口12345。当客户端连接到该端口时，服务器将接收客户端发送的消息，并向客户端发送一条响应消息。