省市区三级联动js和json

##后台代码
package com.es.controller;

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

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.es.entity.Area;
import com.es.entity.City;
import com.es.entity.Province;
import com.es.serivce.AreaSerivce;
import com.es.serivce.CitySerivce;
import com.es.serivce.provinceSerivce;
import com.google.gson.Gson;
@WebServlet("/ajax01")
public class Ajax01 extends HttpServlet{
@Override
protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
try {
//先获取方法名，然后利用反射调用相应的方法即可
String method = req.getParameter(“method”);
//调用当前对象的响应方法
Class clz = this.getClass();
Method m = clz.getMethod(method,HttpServletRequest.class,HttpServletResponse.class);
//调用方法
m.invoke(this, req,resp);
}catch (Exception e) {
e.printStackTrace();
System.out.println(“方法调用异常”);
}
}
public void province(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.setContentType(“text/html;charset=utf-8”);
//获取所有的省份，然后转成json,响应给页面
provinceSerivce provinceSerivce = new provinceSerivce();
List list = provinceSerivce.getAllAddr();
//转json
String json = new Gson().toJson(list);
//响应
resp.getWriter().print(json);
return;
}
public void city(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.setContentType(“text/html;charset=utf-8”);
req.setCharacterEncoding(“utf-8”);
String code = req.getParameter(“city_c”);
//获取所有的省份，然后转成json,响应给页面
CitySerivce citySerivce = new CitySerivce();
List list = citySerivce.getAllAddr(code);
//转json
String json = new Gson().toJson(list);
//响应
resp.getWriter().print(json);
return;
}
public void area(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
resp.setContentType(“text/html;charset=utf-8”);
req.setCharacterEncoding(“utf-8”);
String code = req.getParameter(“code_c”);
//获取所有的省份，然后转成json,响应给页面
AreaSerivce areaSerivce = new AreaSerivce();
List list = areaSerivce.getAllAddr(code);
//转json
String json = new Gson().toJson(list);
//响应
resp.getWriter().print(json);
return;
}
}