JSON+AJAX的应用
主要内容：
- JSON数据格式
- AJAX异步请求
- 利用JSON+AJAX进行用户名的判断
- 利用JSON＋AJAX进行省、市、区信息联动
详细记录：
1 JSON数据格式
JS中的JSON
JAVA中的JSON：
引入JAR包：
commons-beanutils-1.7.0.jar
commons-collections-3.1.jar
commons-httpclient-3.1.jar
commons-lang-2.5.jar
commons-logging-1.0.4.jar
ezmorph-1.0.3.jar
json-lib-2.1-jdk15.jar
测试类：
（1）自定义JSON类对象
import net.sf.json.JSONObject;
public class TestJSON {
public static void main(String[] args) {
JSONObject obj=new JSONObject();
obj.put("name", "zb");
obj.put("age", 20);
obj.put("birth", "1998-11-1");
System.out.println(obj);
}
}执行：{“birth”:”1998-11-1”,”age”:20,”name”:”zb”}
（2）由MAP生成JSON类对象
public class TestJSON {
public static void main(String[] args) {
Map obj=new HashMap();
obj.put("name", "zb");
obj.put("age", 20);
obj.put("birth", "1998-11-1");
JSONObject objJSON=JSONObject.fromObject(obj);
System.out.println(objJSON);
}
}执行结果：{“birth”:”1998-11-1”,”name”:”zb”,”age”:20}
（3）由JAVA集合生成JSON数组对象
public class TestJSON {
public static void main(String[] args) {
List执行结果：[{“birth”:”1998-11-1”,”age”:20,”name”:”zb”},{“birth”:”1996-1-1”,”age”:22,”name”:”zb2”}]
（4）由JavaBean生成JSON类对象
User类的定义：
package cn.sdut.po;
public class User {
private int id;
private String name;
private String password;
private String sex;
private String birthday;
private String hobby;
private String telephone;
private String address;
private int type;
public User() {
super();
}
public User(int id, String name, String password, String sex,
String birthday, String hobby, String telephone, String address,
int type) {
super();
this.id = id;
this.name = name;
this.password = password;
this.sex = sex;
this.birthday = birthday;
this.hobby = hobby;
this.telephone = telephone;
this.address = address;
this.type = type;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public String getBirthday() {
return birthday;
}
public void setBirthday(String birthday) {
this.birthday = birthday;
}
public String getHobby() {
return hobby;
}
public void setHobby(String hobby) {
this.hobby = hobby;
}
public String getTelephone() {
return telephone;
}
public void setTelephone(String telephone) {
this.telephone = telephone;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public int getType() {
return type;
}
public void setType(int type) {
this.type = type;
}
@Override
public String toString() {
return "User [id=" + id + ", name=" + name + ", password=" + password
+ ", sex=" + sex + ", birthday=" + birthday + ", hobby="
+ hobby + ", telephone=" + telephone + ", address=" + address
+ ", type=" + type + "]";
}
}测试类：
package cn.sdut.po;
import net.sf.json.JSONObject;
public class TestJSON {
public static void main(String[] args) {
User user=new User(1,"李华","1111","女","1999-1-1","体育","122342","淄博",1);
JSONObject userJson=JSONObject.fromObject(user);
System.out.println(userJson.toString());
}
}执行：{“id”:1,”birthday”:”1999-1-1”,”sex”:”女”,”address”:”淄博”,”name”:”李华”,”hobby”:”体育”,”type”:1,”telephone”:”122342”,”password”:”1111”}
2 AJAX异步请求
3 利用JSON+AJAX进行用户名的判断
过程分析：
（1）数据库层面的支持——根据用户名查询用户对象
（2）JSP页面的支持——“姓名”文本框内容改变时，需要响应onchange事件（或者onblur事件），另外，在姓名输入框后加个提示信息的控件，用于显示用户名是否可用。
（3）Servlet的处理——获得用户名，根据用户名查询用户，若查到，就返回页面“true”，否则返回“false”
（4）JSP页面根据返回值“true”还是“false”，进行不同的处理。 详细代码：
（1）数据库层面的支持——根据用户名查询用户对象（UserDao.java）
DBUtilsBaseDao.java
package cn.sdut.dao;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.List;
import org.apache.commons.dbutils.DbUtils;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanListHandler;
public class DBUtilsBaseDao {
//得到数据库连接
public Connection getConn()
{
Connection conn=null;
DbUtils.loadDriver("com.mysql.jdbc.Driver");
try {
conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/shopping?useUnicode=true&characterEncoding=utf-8","root","usbw");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return conn;
}
//增、删、改数据库的方法
public int update(String sql,Object... param)
{
int result=0;
Connection conn=getConn(); //得到连接
QueryRunner runner=new QueryRunner(); //得到运行对象
try {
result=runner.update(conn, sql, param); //进行数据库操作
} catch (SQLException e) {
e.printStackTrace();
}
finally
{
DbUtils.closeQuietly(conn); //关闭数据库连接
}
return result;
}
//数据库查询
public List query(String sql,Class clazz,Object... param)
{
List list=null;
Connection conn=getConn(); //得到连接
QueryRunner runner=new QueryRunner(); //得到运行对象
try {
list=runner.query(conn,sql,new BeanListHandler(clazz),param); //进行数据库操作
} catch (SQLException e) {
e.printStackTrace();
}
finally
{
DbUtils.closeQuietly(conn); //关闭数据库连接
}
return list;
}
//批量操作数据库的方法
public boolean bactchUpdate(String sql,Object[][] param)
{
int[] result=new int[param.length];
int r=1;
Connection conn=getConn(); //得到连接
QueryRunner runner=new QueryRunner(); //得到运行对象
try {
result=runner.batch(conn,sql,param);// 批量进行数据库操作
} catch (SQLException e) {
e.printStackTrace();
}
finally
{
DbUtils.closeQuietly(conn); //关闭数据库连接
}
//对返回数据进行加工，将整型数组转化为布尔类型
for(int i=0;ireturn r>0?true:false;
}
} UserDao.java
package cn.sdut.dao;
import java.util.List;
import cn.sdut.po.User;
public class UserDao extends DBUtilsBaseDao {
// ………….
//用户注册或增加用户时根据用户名查询用户（是否存在）
public User findUserByName(String name)
{
User user=null;
String sql="select * from users where name=?";
Object[] param=new Object[]{name};
List users=query(sql, User.class, param);
if(users!=null&&users.size()>0)
{
user=users.get(0);
}
return user;
}
} （2）JSP页面的支持——“姓名”文本框内容改变时，需要响应onchange事件（或者onblur事件），另外，在姓名输入框后加个提示信息的控件，用于显示用户名是否可用。（m_addUser.jsp）
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP ’addUser.jsp’ starting pagetitle>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<script src="js/calendar.js">script>
<style type="text/css">
body {
text-align: center;
}
style>
<script>
function checkUser()
{
var name=document.getElementById("name").value;
var httpRequest=new XMLHttpRequest();
httpRequest.open("GET","<%=path%>/UserServlet?method=byname&name="+name,true);
httpRequest.onreadystatechange=function()
{
if(httpRequest.status==200&&httpRequest.readyState==4)
{
var response=httpRequest.responseText;
if(response=="true")
{
document.getElementById("info").innerHTML="用户名已存在";
document.getElementById("name").value="";
}
else
{
document.getElementById("info").innerHTML="用户名可用";
}
}
}
httpRequest.send();
}
script>
head>
<body>
<br>
<form name="form1" method="post" action="<%=path%>/UserServlet?method=add">
<table width="496" border="1">
<caption>用户添加caption>
<tr>
<td width="92" height="38" align="center">用户名：td>
<td width="157">
<input type="text" name="name" id="name" onblur="checkUser()">
<span id="info" style="color:red">span>
td>
tr>
<tr>
<td height="41" align="center">密码：td>
<td><input type="text" name="password" id="password">td>
tr>
<tr>
<td height="41" align="center">出生日期：td>
<td><input type="text" name="birthday" id="birthday" onclick="new Calendar().show(this)">td>
tr>
<tr>
<td height="44" align="center">性别：td>
<td><input type="radio" name="sex" id="sex" value="男">男
<input type="radio" name="sex" id="sex2" value="女"> 女
td>
tr>
<tr>
<td align="center">爱好：td>
<td><p>
<label>
<input type="checkbox" name="hobby" value="运动" id="hobby_0">运动label>
<label>
<input type="checkbox" name="hobby" value="音乐" id="hobby_1">音乐label>
<label>
<input type="checkbox" name="hobby" value="阅读" id="hobby_2">阅读label>
<br>
p>td>
tr>
<tr>
<td align="center">地址：td>
<td><textarea name="address" id="address" cols="45" rows="5">textarea>td>
tr>
<tr>
<td height="42" align="center">联系电话：td>
<td><input type="text" name="telephone" id="telephone">td>
tr>
<tr>
<td height="64" colspan="2" align="center">
<input type="submit" name="submit" id="submit" value="提交">
<input type="reset" name="button" id="button" value="取消">td>
tr>
table>
form>
body>
html>（3）Servlet的处理——获得用户名，根据用户名查询用户，若查到，就返回页面“true”，否则返回“false”。（UserServlet.java）
package cn.sdut.servlet;
import java.io.IOException;
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 javax.servlet.http.HttpSession;
import cn.sdut.dao.UserDao;
import cn.sdut.po.User;
@WebServlet("/UserServlet")
public class UserServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
UserDao userDao = new UserDao();
public UserServlet() {
super();
// TODO Auto-generated constructor stub
}
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
String method = request.getParameter("method");
switch (method) {
//………
case "byname":
queryUserByName(request,response);
break;
}
}
private void queryUserByName(HttpServletRequest request,
HttpServletResponse response) throws IOException {
String result="false";
String name = request.getParameter("name");
User user = userDao.findUserByName(name);
if(user!=null)
{
result="true";
}
response.getWriter().write(result);
}
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}（4）JSP页面根据返回值“true”还是“false”，进行不同的处理。（m_addUser.jsp）
var response=httpRequest.responseText;
if(response=="true")
{
document.getElementById("info").innerHTML="用户名已存在";
document.getElementById("name").value="";
}
else
{
document.getElementById("info").innerHTML="用户名可用";
}（5）程序执行：
http://localhost:8080/adduser/m_addUser.jsp
4 利用JSON＋AJAX进行省、市、区信息联动
过程分析：
（0）创建表syscode，向里面加入省、市、区的数据，建立与该表对应的实体类
/*
Navicat MySQL Data Transfer
Source Server : 127.0.0.1_3306
Source Server Version : 50621
Source Host : 127.0.0.1:3306
Source Database : procitydis
Target Server Type : MYSQL
Target Server Version : 50621
File Encoding : 65001
Date: 2016-08-05 11:37:55
*/
SET FOREIGN_KEY_CHECKS=0;
-- ----------------------------
-- Table structure for syscode
-- ----------------------------
DROP TABLE IF EXISTS `syscode`;
CREATE TABLE `syscode` (
`pid` int(11) NOT NULL AUTO_INCREMENT,
`pname` varchar(20) NOT NULL,
`pcode` varchar(20) NOT NULL,
`pvalue` varchar(20) NOT NULL,
`fcode` varchar(20) NOT NULL,
PRIMARY KEY (`pid`)
) ENGINE=InnoDB AUTO_INCREMENT=47 DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of syscode
-- ----------------------------
INSERT INTO `syscode` VALUES (’1’, ’省市’, ’01’, ’北京’, ’0’);
INSERT INTO `syscode` VALUES (’2’, ’省市’, ’02’, ’上海’, ’0’);
INSERT INTO `syscode` VALUES (’3’, ’省市’, ’03’, ’广州’, ’0’);
INSERT INTO `syscode` VALUES (’4’, ’省市’, ’04’, ’山东’, ’0’);
INSERT INTO `syscode` VALUES (’5’, ’省市’, ’0101’, ’东城区’, ’01’);
INSERT INTO `syscode` VALUES (’6’, ’省市’, ’010101’, ’东华门街道’, ’0101’);
INSERT INTO `syscode` VALUES (’7’, ’省市’, ’010102’, ’景山街道’, ’0101 ’);
INSERT INTO `syscode` VALUES (’8’, ’省市’, ’0102’, ’西城区’, ’01’);
INSERT INTO `syscode` VALUES (’9’, ’省市’, ’010201’, ’西长安街街道’, ’0102’);
INSERT INTO `syscode` VALUES (’10’, ’省市’, ’010202’, ’广安门内街道’, ’0102 ’);
INSERT INTO `syscode` VALUES (’11’, ’省市’, ’0103’, ’朝阳区’, ’01’);
INSERT INTO `syscode` VALUES (’12’, ’省市’, ’010301’, ’南磨房地区’, ’0103’);
INSERT INTO `syscode` VALUES (’13’, ’省市’, ’010302’, ’高碑店地区’, ’0103 ’);
INSERT INTO `syscode` VALUES (’14’, ’省市’, ’0201’, ’黄浦’, ’02’);
INSERT INTO `syscode` VALUES (’15’, ’省市’, ’020101’, ’黄浦1’, ’0201’);
INSERT INTO `syscode` VALUES (’16’, ’省市’, ’020102’, ’黄浦2’, ’0201’);
INSERT INTO `syscode` VALUES (’17’, ’省市’, ’0202’, ’徐汇’, ’02’);
INSERT INTO `syscode` VALUES (’18’, ’省市’, ’020201’, ’徐汇1’, ’0202’);
INSERT INTO `syscode` VALUES (’19’, ’省市’, ’020201’, ’徐汇2’, ’0202’);
INSERT INTO `syscode` VALUES (’20’, ’省市’, ’0203’, ’长宁’, ’02’);
INSERT INTO `syscode` VALUES (’21’, ’省市’, ’020301’, ’长宁1’, ’0203’);
INSERT INTO `syscode` VALUES (’22’, ’省市’, ’020302’, ’长宁2’, ’0203’);
INSERT INTO `syscode` VALUES (’23’, ’省市’, ’0301’, ’越秀区’, ’03’);
INSERT INTO `syscode` VALUES (’24’, ’省市’, ’030101’, ’越秀1’, ’0301’);
INSERT INTO `syscode` VALUES (’25’, ’省市’, ’030102’, ’越秀2’, ’0301’);
INSERT INTO `syscode` VALUES (’26’, ’省市’, ’0302’, ’天河区’, ’03’);
INSERT INTO `syscode` VALUES (’27’, ’省市’, ’030201’, ’天河1’, ’0302’);
INSERT INTO `syscode` VALUES (’28’, ’省市’, ’030201’, ’天河2’, ’0302’);
INSERT INTO `syscode` VALUES (’29’, ’省市’, ’0303’, ’白云区’, ’03’);
INSERT INTO `syscode` VALUES (’30’, ’省市’, ’030301’, ’白云1’, ’0303’);
INSERT INTO `syscode` VALUES (’31’, ’省市’, ’030201’, ’白云2’, ’0303’);
INSERT INTO `syscode` VALUES (’32’, ’省市’, ’0401’, ’济南’, ’04’);
INSERT INTO `syscode` VALUES (’33’, ’省市’, ’040101’, ’历下’, ’0401’);
INSERT INTO `syscode` VALUES (’34’, ’省市’, ’030202’, ’槐荫’, ’0302’);
INSERT INTO `syscode` VALUES (’35’, ’省市’, ’0402’, ’青岛’, ’04’);
INSERT INTO `syscode` VALUES (’36’, ’省市’, ’040201’, ’市南’, ’0402’);
INSERT INTO `syscode` VALUES (’37’, ’省市’, ’040201’, ’黄岛’, ’0402’);
INSERT INTO `syscode` VALUES (’38’, ’省市’, ’0403’, ’烟台’, ’04’);
INSERT INTO `syscode` VALUES (’39’, ’省市’, ’040301’, ’荣成 ’, ’0403’);
INSERT INTO `syscode` VALUES (’40’, ’省市’, ’040302’, ’文登’, ’0403’);
INSERT INTO `syscode` VALUES (’41’, ’省市’, ’0405’, ’淄博’, ’04’);
INSERT INTO `syscode` VALUES (’42’, ’省市’, ’040501’, ’张店’, ’0405’);
INSERT INTO `syscode` VALUES (’43’, ’省市’, ’040502’, ’淄川’, ’0405’);
INSERT INTO `syscode` VALUES (’44’, ’省市’, ’040503’, ’周村’, ’0405’);
INSERT INTO `syscode` VALUES (’45’, ’省市’, ’040504’, ’临淄’, ’0405’);
INSERT INTO `syscode` VALUES (’46’, ’省市’, ’040505’, ’博山’, ’0405’);Syscode.java
package cn.sdut.po;
public class Syscode {
private int id;
private String pname;
private String pcode;
private String pvalue;
private String fcode;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getPname() {
return pname;
}
public void setPname(String pname) {
this.pname = pname;
}
public String getPcode() {
return pcode;
}
public void setPcode(String pcode) {
this.pcode = pcode;
}
public String getPvalue() {
return pvalue;
}
public void setPvalue(String pvalue) {
this.pvalue = pvalue;
}
public String getFcode() {
return fcode;
}
public void setFcode(String fcode) {
this.fcode = fcode;
}
}（1）数据库层面，提供查询省、市、区的方法
package cn.sdut.dao;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.List;
import org.apache.commons.dbutils.DbUtils;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanListHandler;
public class DBUtilsBaseDao {
//得到数据库连接
public Connection getConn()
{
Connection conn=null;
DbUtils.loadDriver("com.mysql.jdbc.Driver");
try {
conn=DriverManager.getConnection("jdbc:mysql://localhost:3306/shopping?useUnicode=true&characterEncoding=utf-8","root","usbw");
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return conn;
}
//增、删、改数据库的方法
public int update(String sql,Object... param)
{
int result=0;
Connection conn=getConn(); //得到连接
QueryRunner runner=new QueryRunner(); //得到运行对象
try {
result=runner.update(conn, sql, param); //进行数据库操作
} catch (SQLException e) {
e.printStackTrace();
}
finally
{
DbUtils.closeQuietly(conn); //关闭数据库连接
}
return result;
}
//数据库查询
public List query(String sql,Class clazz,Object... param)
{
List list=null;
Connection conn=getConn(); //得到连接
QueryRunner runner=new QueryRunner(); //得到运行对象
try {
list=runner.query(conn,sql,new BeanListHandler(clazz),param); //进行数据库操作
} catch (SQLException e) {
e.printStackTrace();
}
finally
{
DbUtils.closeQuietly(conn); //关闭数据库连接
}
return list;
}
//批量操作数据库的方法
public boolean bactchUpdate(String sql,Object[][] param)
{
int[] result=new int[param.length];
int r=1;
Connection conn=getConn(); //得到连接
QueryRunner runner=new QueryRunner(); //得到运行对象
try {
result=runner.batch(conn,sql,param);// 批量进行数据库操作
} catch (SQLException e) {
e.printStackTrace();
}
finally
{
DbUtils.closeQuietly(conn); //关闭数据库连接
}
//对返回数据进行加工，将整型数组转化为布尔类型
for(int i=0;ireturn r>0?true:false;
}
} package cn.sdut.dao;
import java.util.List;
import cn.sdut.po.Syscode;
public class SyscodeDao extends DBUtilsBaseDao {
public List findPCD(String pname, String fcode) {
List pcd = null;
String sql = "select * from syscode where pname=? and fcode=?";
pcd=query(sql, Syscode.class, new String[] { pname, fcode });
System.out.println(pcd);
return pcd;
}
} （2）页面层提供省、市、区3个下拉列表框，实现信息联动。
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP ’index.jsp’ starting pagetitle>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<script type="text/javascript">
function showCity()
{ //显示市
var value=document.getElementById("province").value;
var httpRequest=new XMLHttpRequest();
httpRequest.open("GET","<%=path%>/SyscodeServlet?method=city&fcode="+value,true);
httpRequest.onreadystatechange=function(){
if(httpRequest.status==200 && httpRequest.readyState==4)
{
var cities=httpRequest.responseText;
var jsonCities=eval("("+cities+")");
var obj=document.getElementById("city");
obj.options.length=0;
for(var i=0;inew Option(jsonCities[i].pvalue,jsonCities[i].pcode));
}
showDist();
}
};
httpRequest.send();
}
function showDist()
{ //显示区
var value=document.getElementById("city").value;
var httpRequest=new XMLHttpRequest();
httpRequest.open("GET","<%=path%>/SyscodeServlet?method=city&fcode="+value,true);
httpRequest.onreadystatechange=function(){
if(httpRequest.status==200 && httpRequest.readyState==4)
{
var cities=httpRequest.responseText;
var jsonCities=eval("("+cities+")");
var obj=document.getElementById("dist");
obj.options.length=0;
for(var i=0;inew Option(jsonCities[i].pvalue,jsonCities[i].pcode));
}
}
};
httpRequest.send();
}
script>
head>
<body onload="showCity()">
<select id="province" name="province" onchange="showCity()">
<c:forEach items="${provinceList }" var="province">
<option value="${province.pcode }">${province.pvalue }option>
c:forEach>
select>
<select id="city" name="city" onchange="showDist()">
select>
<select id="dist" name="dist">
select>
body>
html> （3）Servlet层面——完成2个任务：
l 页面加载时显示所有省的信息； l 异步请求显示市和区的信息
package cn.sdut.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
import cn.sdut.dao.SyscodeDao;
import cn.sdut.po.Syscode;
public class SyscodeServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
String method=request.getParameter("method");
switch(method)
{
case "province":
queryProvince(request,response);
break;
case "city":
queryCity(request,response);
break;
case "dist":
queryCity(request,response);
break;
}
}
private void queryProvince(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
SyscodeDao dao=new SyscodeDao();
List provinceList = dao.findPCD("省市", "0");
//System.out.println(provinceList);
request.setAttribute("provinceList", provinceList);
request.getRequestDispatcher("/index.jsp").forward(request, response);
}
private void queryCity(HttpServletRequest request,
HttpServletResponse response) throws IOException {
System.out.println(11);
String fcode=request.getParameter("fcode");
SyscodeDao dao=new SyscodeDao();
List provinceList = dao.findPCD("省市", fcode);
JSONArray cities=JSONArray.fromObject(provinceList);
System.out.println(provinceList);
response.getWriter().write(cities.toString());
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request,response);
}
} （4）执行：
http://localhost:8080/PCD/SyscodeServlet?method=province