老师，在idea中导入jsonJar包后 错误代码500

package com.ajax;

import com.alibaba.fastjson.JSON;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.*;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

@WebServlet(name = "NewsServlet", value = "/NewsServlet")
public class NewsServlet extends HttpServlet {
@Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 初始化数据
        List newsList =  new ArrayList();
        newsList.add(new News("1.腾讯新闻","2020-9-20",".。。","第四季度营业额度突破200亿"));
        newsList.add(new News("2.腾讯新闻","2020-9-20","。。。","第四季度营业额度突破200亿"));
        newsList.add(new News("3.腾讯新闻","2020-9-20","。。。","第四季度营业额度突破200亿"));
        newsList.add(new News("4.腾讯新闻","2020-9-20","。。。","第四季度营业额度突破200亿"));
        String str = JSON.toJSONString(newsList);

    }



}