我想从事Java后端开发，请给我一段代码示例

当然，我可以给你一个 Java 后端开发的示例代码：

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;

public class Server {
    public static void main(String[] args) throws IOException {
        ServerSocket serverSocket = new ServerSocket(8080);
        System.out.println("Server started on port 8080...");

        while (true) {
            Socket clientSocket = serverSocket.accept();
            System.out.println("Client connected: " + clientSocket.getInetAddress().getHostAddress());

            Thread thread = new Thread(new ClientHandler(clientSocket));
            thread.start();
        }
    }
}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;

public class ClientHandler implements Runnable {
    private Socket clientSocket;

    public ClientHandler(Socket clientSocket) {
        this.clientSocket = clientSocket;
    }

    @Override
    public void run() {
        try {
            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("Received message from client: " + inputLine);
                out.println("Server received message: " + inputLine);
            }

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

这是一个简单的 Java 后端服务器，它监听 8080 端口，接受客户端的连接，并在接收到客户端的消息后，将消息原样返回给客户端。当然，这只是一个示例代码，实际的 Java 后端开发需要更加复杂的代码和技术。