如何使用Java通过Web服务以JSON格式公开数据？

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.fasterxml.jackson.databind.ObjectMapper;

@WebServlet("/data")
public class DataServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("application/json");

        // 创建一个Java对象，例如一个Map或自定义类
        MyData data = new MyData();
        data.setName("John Doe");
        data.setAge(30);

        // 使用Jackson将对象转换为JSON字符串
        ObjectMapper objectMapper = new ObjectMapper();
        String jsonData = objectMapper.writeValueAsString(data);

        // 将JSON字符串写入响应
        PrintWriter out = response.getWriter();
        out.println(jsonData);
    }
}