以下是一个简单的Java示例，展示如何解析HTTP请求：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.HashMap;
import java.util.Map;

public class SimpleHTTPParser {

    public static void main(String[] args) throws IOException {
        ServerSocket serverSocket = new ServerSocket(8080);
        System.out.println("服务器已启动，监听端口 8080");

        while (true) {
            Socket clientSocket = serverSocket.accept();
            handleClient(clientSocket);
        }
    }

    private static void handleClient(Socket socket) throws IOException {
        InputStream input = socket.getInputStream();
        BufferedReader reader = new BufferedReader(new InputStreamReader(input));

        // 解析请求行
        String requestLine = reader.readLine();
        if (requestLine == null || requestLine.isEmpty()) {
            socket.close();
            return;
        }
        String[] requestParts = requestLine.split(" ");
        String method = requestParts[0];
        String uri = requestParts[1];
        String httpVersion = requestParts[2];
        System.out.println("请求方法: " + method);
        System.out.println("请求URI: " + uri);
        System.out.println("HTTP版本: " + httpVersion);

        // 解析头部字段
        Map<String, String> headers = new HashMap<>();
        String headerLine;
        while (!(headerLine = reader.readLine()).isEmpty()) {
            String[] headerParts = headerLine.split(": ", 2);
            headers.put(headerParts[0], headerParts[1]);
        }
        System.out.println("请求头: " + headers);

        // 解析消息体（如果存在）
        if (headers.containsKey("Content-Length")) {
            int contentLength = Integer.parseInt(headers.get("Content-Length"));
            char[] body = new char[contentLength];
            reader.read(body, 0, contentLength);
            System.out.println("消息体: " + new String(body));
        }

        // 发送简单响应
        String response = "HTTP/1.1 200 OK\r\n" +
                          "Content-Type: text/plain\r\n" +
                          "Content-Length: 12\r\n" +
                          "\r\n" +
                          "Hello World!";
        socket.getOutputStream().write(response.getBytes());
        socket.close();
    }
}