问题描述

servlet +ajax 关于 典型应用_三级联动__城市到部门的时 出错了，谁能帮我下

servlet +ajax 关于发送$.getJson EmployeeServlet 无法得到，谁能帮我解决下

在学习 51CTO下载-11. 尚硅谷_佟刚_Ajax_典型应用_三级联动__城市到部门的 Ajax 实现
如图

有那个高手帮我解决下。在这先谢过了

解决方案

解决方案二：

解决方案三：

以下是代码**

**

package com;

import java.io.IOException;
import java.io.PrintWriter;
import java.lang.reflect.Method;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.fasterxml.jackson.databind.ObjectMapper;

import beans.Department;
import beans.Location;

import dao.BaseDao;

public class EmployeeServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

private BaseDao baseDao = new BaseDao();

            public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

                String methodName = request.getParameter("method");
                try{
                        Method method = getClass().getDeclaredMethod(methodName,HttpServletRequest.class, HttpServletResponse.class);
                        method.invoke(this, request,response);
                    }catch(Exception e){
                        e.printStackTrace();
                    }

            }

public void listLocations(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {

        String sql = "SELECT location_id locationId, city FROM locations";
        List<Location> locations = baseDao.getForList(sql, Location.class);
        request.setAttribute("locations", locations);

        System.out.println("locations="+locations);

        request.getRequestDispatcher("/WEB-INF/pages/employees.jsp").forward(request, response);

}

public void listDepartments(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {

    String locationId = request.getParameter("locationId");
    String sql = "SELECT departmet_id departmentId, department_name departmentName"+
                "FROM departments d"+
                "WHERE d.location_id=?";

    List<Department> departments = baseDao.getForList(sql, Department.class, Integer.parseInt(locationId));
    ObjectMapper mapper = new ObjectMapper();
    String result = mapper.writeValueAsString(departments);
    System.out.println(result);

    response.setContentType("text/javascript");
    response.getWriter().print(result);

}

}

解决方案四：

解决方案五：

自己顶一下贴子**__**

解决方案六：

自己顶一下贴子**__**

解决方案七：

自己顶一下贴子**__**

解决方案八：

自己顶一下贴子**__**