jQuery

jQuery入门与高级应用
本文详细介绍了jQuery的基础概念,包括其优点、初始化方法、选择器的使用,以及jQuery对象与JS对象的转换技巧。深入探讨了jQuery插件的开发过程,如命名规范、实例方法的扩展、面向集合的操作及多行指令的简化。此外,还涵盖了Ajax的基本原理及Jackson库在JSON处理上的应用,通过省市级联动案例展示了jQuery与Ajax结合的实际操作。

一.jquery入门

  1. 什么是jQuery
    它是一个轻量级的javascript类库
    注1:就一个类“jQuery”,简写“$”

  2. jQuery优点
    2.1 总是面向集合
    2.2 多行操作集于一行

  3. hello jQuery
    3.1 导入js库

<script type="text/javascript" src=""></script>

3.2 $(fn)做为程序入口
( f n ) 、 (fn)、 (fn)(document).ready(fn)与window.onload的区别?

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery.min.js"></script>
<title>Insert title here</title>
<script type="text/javascript">
/* $(fn)、$(document).ready(fn)与window.onload的区别? 项目维护时用*/
  //第一种
  $(function() {
	alert("hello jquery");
}) 
  //第二种
  $(document).ready(function() {
	alert("hello jquery2");
}) 
//第三种
window.onload=function(){
	alert("hello jquery3");
}
/* 结论:$(fn)、$(document).ready(fn)是等价的,哪个在前就执行哪个
 jsp的demo树结构加载完毕即刻调用方法
 window.onload最后执行 
 jsp的dom树加载完,css,js等静态资源加载完毕执行
 */
</script>
</head>
<body>

</body>
</html>
  1. jQuery三种工厂方法 (demo2.jsp)
    4.1 jQuery(exp[,context])
    exp:选择器
    context:上下文,环境/容器,documemt
    注1:选择器,css选择器
    标签选择器
    ID选择器
    类选择器
    包含选择器:E1 E2
    组合选择器:E1,E2,E3
    自定义选择器::exp
<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery.min.js"></script>
<title>Insert title here</title>
<script type="text/javascript">
  $(function() {
	  //利用a标签获取jquery实例
	/* $("a").click(function() {
		alert("啦啦啦");
	}); */
	
	//利用id=a3获取jquery实例
	/* $("#a3").click(function() {
		alert("lalala");
	}); */
	
	//利用类获取jquery实例
	/* $(".c1").click(function() {
		alert("lalala");
	}); */
	
	//包含选择器
	/* $("p a").click(function() {
		alert("lalala");
	}); */
	
	//组合选择器
	/* $("a,span").click(function() {
		alert("lalala");
	}); */
	
	//讲解第二个参数的作用(在div标签内部寻找a标签,然后给找到的标签添加事件)
	//如果第二个参数没有填,那么默认是documentr
	$("a","div").click(function() {
		alert("lalala");
	});
})
</script>

</head>
<body>
	<p>
		<a id="a1" class="c1" href="#">点我1</a>
	</p>
	<p>
		<a id="a2" class="c2" href="#">点我2</a>
	</p>
	<p>
		<a id="a3" class="c3" href="#">点我3</a>
	</p>
	<div>
		<a id="a4" class="c1" href="#">点我4</a>
	</div>
	<div>
		<p>
			<a id="a5" class="c1" href="#">点我5</a>
		</p>
	</div>
	
	<span>点我</span>

</body>
</html>

4.2 jQuery(html) (demo3.jsp)
html:基于html的一个字符串
4.3 jQuery(element) (demo3.jsp)
element:js对象,表示一个html元素对象
js对象与jquery对象的相互转换
注1:$就是jQuery简写

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery.min.js"></script>
<title>Insert title here</title>
<script type="text/javascript">
  $(function() {
	$(":input[name='name1']").click(function() {
		//在id=selId1的select的jquery实例上追加<option value='1'>湖南省</option>的html jquery实例
		$("#selId1").append("<option value='1'>湖南省</option>");
	});
	
	$(":input[name='name2']").click(function() {
		//将"<option value='1'>长沙</option>"的html jquery实例加到id=selId1的select标签jquery实例中
		$("<option value='1'>长沙</option>").appendTo("#selId2");
		
		
		//jquery怎么获取
		/* var $h1=$("#h1");
		alert($h1.val());
		
		//jquery对象转js对象
		var h1Node=$h1.get(0);//(看成集合)
		var h1Node=$h1[0];//看成数组
		alert(h1Node.value); */
		
		var h2Node=document.getElementById("h2");
		alert(h2Node.value);
		//js 对象转jquery对象
		$h2Node=$(h2Node);
		alert($h2Node.val());
		
	});
})
</script>
</head>
<body>


	<select id="selId1">
		<option value="-1">---请选择---</option>
	</select>
	<select id="selId2">
		<option value="-1">---请选择---</option>
	</select>
	<input name="name1" value="add1" type="button">
	<input name="name2" value="add2" type="button">
	
	<input type="hidden" id="h1" value="h1">
	<input type="hidden" id="h2" value="h2">
	<input type="hidden" id="h3" value="h3">
</body>
</html>
  1. jQuery程序的入口
    $(document).ready(fn)
    $(fn);

  2. this指针的作用 (demo4.jsp)
    6.1 事件源(获取当前按钮的按钮值)
    6.2 当前元素(点击按钮,获取所有a标签的值)

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery.min.js"></script>
<title>Insert title here</title>
<script type="text/javascript">
  $(function() {//给input添加点击事件
	$(":input").click(function() {
		//this指的是事件源
		alert(this.value);
		$("a").each(function(index,item) {
			//this指的是当前元素
			alert(index+","+$(this).html()+","+$(item).html());
		});
	});
})
</script>
</head>
<body>
	<p>
		<a id="a1" class="c1" href="#">点我1</a>
	</p>
	<p>
		<a id="a2" class="c2" href="#">点我2</a>
	</p>
	<p>
		<a id="a3" class="c3" href="#">点我3</a>
	</p>
	<div>
		<a id="a4" class="c1" href="#">点我4</a>
	</div>
	<div>
		<p>
			<a id="a5" class="c1" href="#">点我5</a>
		</p>
	</div>
	
	<input type="button" value="ok">

</body>
</html>
  1. 使用jquery动态给table添加样式
<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery.min.js"></script>
<style type="text/css">
   .fen {
	background: #ff66ff;
}

.yello {
	background: #ffff66;
}

.red {
	background: #ff3333;
}
</style>
<script type="text/javascript">
   $(function() {
	$("table tr:eq(0)").addClass("yello");
	$("table tr:gt(0)").addClass("fen");
	
	$("table tr:gt(0)").hover(function name() {
		$(this).removeClass().addClass("fen");
	},function(){
		$(this).removeClass().addClass("red");
	});
})
</script>
<title>Insert title here</title>
</head>
<body>
	<table border="1" width="100%">
		<tr>
			<td>书名</td>
			<td>作者</td>
			<td>点击量</td>
		</tr>
		<tr>
			<td>圣墟</td>
			<td>辰东</td>
			<td>10万</td>
		</tr>
		<tr>
			<td>飞剑问道</td>
			<td>我吃西红柿</td>
			<td>11万</td>
		</tr>
		<tr>
			<td>杀神</td>
			<td>逆苍天</td>
			<td>22万</td>
		</tr>
		<tr>
			<td>龙王传说</td>
			<td>唐家三少</td>
			<td>18万</td>
		</tr>
		<tr>
			<td>斗破苍穹</td>
			<td>天蚕拖豆</td>
			<td>1万</td>
		</tr>
	</table>
</body>
</html>

在这里插入图片描述

二.jquery插件

  1. 插件机制简介
    往jquery类库里面去扩展方法,这类方法就是jquery插件
  2. json的三种格式
    2.1 对象
    {sid:‘s01’,sname:‘zs’}
    2.2 列表/数组
    [1,3,4,5]
    2.3 混合模式
    {id:3,hobby:[‘a’,‘b’,‘c’]}
<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery.min.js"></script>

<script type="text/javascript">
   $(function() {
	//json对象的字符串体现形式
	var jsonObj1={
		sid:'s001',
		sname:'zahngsan'
	};
	console.log(jsonObj1);
	
	//json数组的字符串体现形式
	var jsonArray1=[1,3,4,5];
	console.log(jsonArray1);
	
	//json混合模式的字符串体现形式
	var jsons={id:3,hobby:['a','b','c']};
	console.log(jsons);
})
</script>
<title>Insert title here</title>
</head>
<body>
	
</body>
</html>
  1. . e x t e n d 和 .extend和 .extend.fn.extend
    2.1 $.extend:对象的扩展(或继承)
    $.extend(obj1,obj2,obj3[,…])
    $.extend(obj1,obj2)
    . e x t e n d ( o b j 1 ) / .extend(obj1)/ .extend(obj1)/.method=function(options){…};

2.2 $.fn.extend
. f n . e x t e n d ( o b j 1 ) / / .fn.extend(obj1)// .fn.extend(obj1)//.fn.method=function(options){…};

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery.min.js"></script>

<script type="text/javascript">
   $(function() {
	//$.extend是用来扩充jquery类属性或者方法所用
	var jsonObj2={};
	//用后面的对象扩充第一个对象
	//$.extend(jsonObj2,jsonObj1);
	//讲解扩充至覆盖的问题,之前已经扩充的属性值会被后面的对象所覆盖,如果后面的对象有新的属性,会继续扩充。
	$.extend(jsonObj2,jsonObj1,jsonObj3);
	console.log(jsonObj2);
	
	$.extend({
		hello:function(){
			alert("我来了");
		}
	});
	
	$.hello();
	
	//$.fn.extend是用来扩充jquery实例属性或者方法所用
	$.fn.extend({
		sayHello:function(){
			alert("我又来了");
		}
	});
	$("#yellow").sayHello();
	alert("yellow");
})
</script>
<title>Insert title here</title>
</head>
<body>
	<span id="yellow">yellow</span>
</body>
</html>
  1. jQuery插件的添加
    其实就是给jQuery添加新的实例方法或类方法,然后将功能封闭在其中

jquery.table.css

@charset "UTF-8";
.head {
	background: #ff66ff;
}

.yellow {
	background: #ffff66;
}

.red {
	background: #ff3333;
}

.blue {
	background: #9999ff;
}

.green {
	background: #bbff99;
}
.hui {
	background: #d6d6c2;
}

jquery.table.js

$(function() {
	var defaults={
			head:'fen',
			out:'yellow',
			over:'red'
	}
	$.fn.extend({
		//使用return的原因是让该实例方法支持链编程,好比stringbuffer
		bgColor:function(option){
			$.extend(defaults,option);
			//this指的是插件本身  可以看成一个jquery实例
			return this.each(function(){
				//this指的是当前元素
				$("tr:eq(0)",this).addClass(defaults.head);
				$("tr:gt(0)",this).addClass(defaults.out);
				
				//添加动态效果
				$("tr:gt(0)",this).hover(function(){
					$(this).removeClass().addClass(defaults.over);
				},function(){
					$(this).removeClass().addClass(defaults.out);
				});
			});
		}
	});
	
})

jsp.common.head.jsp

<%@ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8"%>
<!DOCTYPE>
<link href="${pageContext.request.contextPath }/jquery/table/css/jquery.table.css" type="text/css" rel="stylesheet"/>
<script type="text/javascript" src="${pageContext.request.contextPath}/js/jquery.min.js"></script>
<script type="text/javascript" src="${pageContext.request.contextPath}/jquery/table/js/jquery.table.js"></script>

实例应用

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
	<%@include file="/jsp/common/head.jsp" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

<script type="text/javascript">
	$(function(){
		$("table").bgColor({
			head:'yellow',
			out:'red',
			over:'green'
		});
	})
</script>
</head>
<body>
	<table id="t1" border="1" width="100%">
		<tr>
			<td>书名</td>
			<td>作者</td>
			<td>点击量</td>
		</tr>
		<tr>
			<td>圣墟</td>
			<td>辰东</td>
			<td>10万</td>
		</tr>
		<tr>
			<td>飞剑问道</td>
			<td>我吃西红柿</td>
			<td>11万</td>
		</tr>
		<tr>
			<td>杀神</td>
			<td>逆苍天</td>
			<td>22万</td>
		</tr>
		<tr>
			<td>龙王传说</td>
			<td>唐家三少</td>
			<td>18万</td>
		</tr>
		<tr>
			<td>斗破苍穹</td>
			<td>天蚕拖豆</td>
			<td>1万</td>
		</tr>
	</table>

	<table id="t2" border="1" width="100%">
		<tr>
			<td>书名</td>
			<td>作者</td>
			<td>点击量</td>
		</tr>
		<tr>
			<td>圣墟</td>
			<td>辰东</td>
			<td>10万</td>
		</tr>
		<tr>
			<td>飞剑问道</td>
			<td>我吃西红柿</td>
			<td>11万</td>
		</tr>
		<tr>
			<td>杀神</td>
			<td>逆苍天</td>
			<td>22万</td>
		</tr>
		<tr>
			<td>龙王传说</td>
			<td>唐家三少</td>
			<td>18万</td>
		</tr>
		<tr>
			<td>斗破苍穹</td>
			<td>天蚕拖豆</td>
			<td>1万</td>
		</tr>
	</table>
</body>
</html>
  1. jQuery插件开发实例(demo7.jsp demo8.jsp demo9.jsp)
    4.1 命名
    jquery.xxx.js
    4.2 扩展实例方法
    4.3 如何面向集合
    4.4 如何多行集于一行
    4.5 命名参数的写法
    $.extend(defaults,options);

三.ajax

  1. jackson
    Jackson是一个简单基于Java应用库,Jackson可以轻松的将Java对象转换成json对象
    和xml文档,同样也可以将json、xml转换成Java对象
    核心代码:
   ObjectMapper mapper = new ObjectMapper();
   mapper.writeValueAsString(obj);
   int count = md.getColumnCount();
   map.put(md.getColumnName(i), rs.getObject(i));

  1. jackson将java–>json
    2.1 JavaBean/Map
    {}
    2.2 数组/List/Set
    []
    2.3 类里嵌类
    混合模式
package com.xfz.jquery;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.xfz.entity.Student;

/**
 * @author ld
 * 后台的json的三种格式的体现形式
 */
public class Demo1 {
     public static void main(String[] args) throws JsonProcessingException {
    	 //json对象
		Student stu1=new Student("s001","张三");
		ObjectMapper om=new ObjectMapper();
		System.out.println(om.writeValueAsString(stu1));
		
		//json数组
		Student stu2=new Student("s002","李四");
		List<Student> list1=new ArrayList<Student>();
		list1.add(stu1);
		list1.add(stu2);
		System.out.println(om.writeValueAsString(list1));
		
		//json混合格式
		Map<String, Object> map=new HashMap<String, Object>();
		map.put("total", 2);
		map.put("stus", list1);
		System.out.println(om.writeValueAsString(map));
	}

}

  1. java->json死循环
    忽略双向关联的一个方向即可
    @JsonIgnore/程序控制
package com.xfz.jquery;

import java.util.HashSet;
import java.util.Set;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.xfz.entity.Student;
import com.xfz.entity.Teacher;

/**
 * @author ld
 * json死循环问题
 * 1.由双向绑定改为单向绑定,也就是说将彼此之间的关系交于一方维护
 * 2.@JsonIgnore:将彼此循环调用的属性忽略,不参与对象转成json格式
 */
public class Demo3 {
	public static void main(String[] args) throws JsonProcessingException {
		Student stu1 = new Student("s001", "张三");
		Student stu2 = new Student("s002", "李四");
		Teacher tea1 = new Teacher("t001", "王五", null);
		Teacher tea2 = new Teacher("t002", "赵六", null);
		Set<Teacher> teas = new HashSet<>();
		teas.add(tea1);
		teas.add(tea2);
		stu1.setTeas(teas);
		Set<Student> stus = new HashSet<>();
		stus.add(stu1);
		stus.add(stu2);
		tea1.setStus(stus);
		ObjectMapper om = new ObjectMapper();
		System.out.println(om.writeValueAsString(stu1));
		//运行结果:
		//{"sid":"s001","sname":"张三","teas":[{"tid":"t002","sname":"赵六"},{"tid":"t001","sname":"王五"}]}
	}

}

package com.xfz.jquery;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;

/**
 * @author ld
 * javaBean与map集合转换成json字符串的格式是一样的
 */
public class Demo2 {
	public static void main(String[] args) throws JsonProcessingException {
		Map<String, Object> stu1=new HashMap<String, Object>();
		stu1.put("sid", "s001");
		stu1.put("sname", "张三");
		ObjectMapper om=new ObjectMapper();
		System.out.println(om.writeValueAsString(stu1));
		//{"sname":"张三","sid":"s001"}
		
		Map<String, Object> stu2=new HashMap<String, Object>();
		stu2.put("sid", "s002");
		stu2.put("sname", "李四");
		List<Map<String, Object>> list1=new ArrayList<Map<String,Object>>();
		list1.add(stu1);
		list1.add(stu2);
		System.out.println(om.writeValueAsString(list1));
		//[{"sname":"张三","sid":"s001"},{"sname":"李四","sid":"s002"}]
	}

}

四.省市级联动案例

连接数据库,导入之前所写到的类,导入jar包

RegionDao

package com.xfz.dao;

import java.sql.SQLException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.xfz.util.JsonBaseDao;
import com.xfz.util.JsonUtils;
import com.xfz.util.PageBean;
import com.xfz.util.StringUtils;

public class RegionDao extends JsonBaseDao{
	public List<Map<String , Object>> list(Map<String, String[]> paramMap,PageBean pageBean) throws InstantiationException, IllegalAccessException, SQLException{
		//String [] strings=paramMap.get("sid");
		String id = JsonUtils.getParamVal(paramMap, "ID");
		String sql = "select * from ch_region where true";
		if(StringUtils.isBlank(id)) {
			sql += " and parent_id=7459";
		}else {
			sql += " and parent_id="+id;
		}
		return super.executeQuery(sql, pageBean);
	}
	
	public static void main(String[] args) {
		Map<String,String[]> paramMap = new HashMap<>();
		paramMap.put("ID", new String[] {"9504"});
		RegionDao regionDao=new RegionDao();
		try {
			List<Map<String, Object>> list=regionDao.list(paramMap, null);
			System.out.println(list);
		} catch (InstantiationException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

}

RegionServlet

package com.xfz.web;

import java.io.IOException;
import java.sql.SQLException;
import java.util.List;
import java.util.Map;

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 com.xfz.dao.RegionDao;
import com.xfz.util.ResponseUtil;

public class RegionServlet extends HttpServlet{
	private static final long serialVersionUID = -6226475440975457202L;
    private RegionDao regionDao=new RegionDao();
	
	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		doPost(req, resp);
	}
	
	@Override
	protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		try {
			List<Map<String, Object>> list=regionDao.list(req.getParameterMap(), null);
			ObjectMapper om=new ObjectMapper();
			try {
				ResponseUtil.write(resp, om.writeValueAsString(list));
			} catch (Exception e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
		} catch (InstantiationException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (IllegalAccessException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

专门用来处理json数据的工具包

package com.xfz.util;

import java.util.Arrays;
import java.util.Map;

/**
 * @author Administrator
 * 专门用来处理json数据的工具包
 *
 */
public class JsonUtils {
	/**
	 * 从paramMap拿到咱们所需要用到的查询维度,用于sql语句拼接
	 * @param paramMap	获取从jsp页面传递到后台的参数集合(req.getParamterMap)
	 * @param key
	 * @return
	 */
	public static String getParamVal(Map<String,String[]> paramMap, String key) {
		if(paramMap != null && paramMap.size()>0) {
			String[] vals = paramMap.get(key);
			if(vals != null && vals.length > 0) {
				String val = Arrays.toString(vals);
				return val.substring(1, val.length()-1);
			}
			return "";
		}
		return "";
	}
}

配置xml文件

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>web_jQuery</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  
  <servlet>
    <servlet-name>regionServlet</servlet-name>
    <servlet-class>com.xfz.web.RegionServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>regionServlet</servlet-name>
    <url-pattern>/regionServlet</url-pattern>
  </servlet-mapping>
  
</web-app>

demo10.js

$(function(){
	var ctx = $("#ctx").val();
	$.ajax({
		url:ctx+"/regionServlet",
		success:function(data){
			for(index in data){
				//console.log(data[index]);
				$("#province").append("<option value='"+data[index].ID+"'>"+data[index].REGION_NAME+"</option>");
			}
		},
		dataType:"json"
	});
	
	$("#province").change(function(){
		$("option:gt(0)","#city").remove();
		$.ajax({
			url:ctx+"/regionServlet?ID="+this.value,
			success:function(data){
				for(index in data){
					//console.log(data[index]);
					$("#city").append("<option value='"+data[index].ID+"'>"+data[index].REGION_NAME+"</option>");
				}
			},
			dataType:"json"
		});
	});
})

jsp页面

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script type="text/javascript" src="${pageContext.request.contextPath }/js/jquery.min.js"></script>
<script type="text/javascript" src="${pageContext.request.contextPath }/js/demo10.js"></script>
<title>Insert title here</title>
</head>
<body>
<div>
<input type="hidden" id="ctx" value="${pageContext.request.contextPath}">
	<h1>$.ajax实现省市联动</h1>
	<div>
		收货地址&nbsp;&nbsp;
		<select id="province">
			<option selected="selected">---请选择省份---</option>
		</select>&nbsp;&nbsp;
		<select id="city">
			<option selected="selected">---请选择城市---</option>
		</select>&nbsp;&nbsp;
		<select id=" county">
			<option selected="selected">---请选择县区---</option>
		</select>
	</div>
</div>
</body>
</html>

显示:
在这里插入图片描述
在这里插入图片描述

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