使用全方位ajax完成省市联动效果_ajax做省市联动效果-优快云博客

本文链接：https://blog.youkuaiyun.com/ls_wifi/article/details/102695939

本文介绍了如何通过Ajax实现省市联动效果。首先准备数据库表，包括省和市的表结构，并填充模拟数据。接着，当页面加载完成后，利用Ajax发送请求获取所有省份，服务器端拼接JSON数据并返回。前端接收到数据后解析并动态生成HTML，填充到下拉列表中。文章还提到了涉及的JDBC工具类、JSP页面、Servlet以及相关类的设计。

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思路:

准备数据库表

*将mysql的jar包拷贝到WEB-INF/lib目录下

*将DBUtil工具类拷贝到项目中

*建表，模拟数据:

drop table if exists t_city;

drop table if exists t_province;

create table t_province(

code char(3) primary key ,

name varchar(255)

);

insert into t_province(code,name) values('001','山东省');

insert into t_province(code,name) values('002','山西省');

insert into t_province(code,name) values('003','河北省');

create table t_city(

code int primary key auto_increment,

name varchar(255)，

pcode char(3),

foreign key(pcode) refrences t_province(code)

);

insert into t_city(code,name,pcode) values('001','保定市','003');

insert into t_city(code,name,pcode) values('002','石家庄市','003');

insert into t_city(code,name,pcode) values('003','廊坊市','003');

insert into t_city(code,name,pcode) values('004','张家口市','003');

insert into t_city(code,name,pcode) values('005','济南市','001');

insert into t_city(code,name,pcode) values('006','淄博市','001');

insert into t_city(code,name,pcode) values('007','青岛市','001');

insert into t_city(code,name,pcode) values('008','烟台市','001');

insert into t_city(code,name,pcode) values('009','太原市','002');

insert into t_city(code,name,pcode) values('010','运城市','002');

insert into t_city(code,name,pcode) values('011','大同市','002');

insert into t_city(code,name,pcode) values('012','临汾市','002');

commit;

select *from t_city;

select *from t_province;

在页面加载完毕之后，发送ajax请求，获取所有的省份，后台拼接一个JSON格式的字符串，发送给前端，前端解析JSON拼接HTML字符串，将HTML字符串设置到下拉列表当中。

*JSON:

[

{

"code":110,

"name":"山东省"

{

"code":110,

"name":"山东省"

}

{

"code":110,

"name":"山东省"

}

]

*前端接收到以上的JSON字符串之后，eval之后生成json对象，显然它是一个数组，需要在前端使用循环语句取出每一个

json对象，每一个json对象都是一个省份，然后<option value="110">山东省</option>，放到下拉列表<select>标签内部.

1.先导入mysql连接所用的jar包，然后导入工具类

2.接着创建jsp，作为前端发送ajax请求来接收并解析服务器传来的json数据,

3.创建servlet用来响应给jsp页面json格式的数据, 具体代码如下:

jdbc工具类:

package com.bjpowernode.pc.web.action;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class JdbcUtils {
	private JdbcUtils() {
	}
    //加载DB驱动
	static {
		try {
			Class.forName("com.mysql.cj.jdbc.Driver");
		} catch (Exception e) {
			throw new RuntimeException(e + "数据库连接失败");
		}
 
	}
	private static Connection con;
    //获取Connection对象
	public static Connection getConnection() throws SQLException {
		String url = "jdbc:mysql://localhost:3306/mybase?serverTimezone=UTC";
		String username = "root", password = "ls12345";
		if (con == null || con.isClosed()) {
			con = DriverManager.getConnection(url, username, password);
		}
		return con;
	}
 
	
 
	// 关闭资源
	public static void close(Connection con, Statement stat, ResultSet rs) throws SQLException {
 
		if (con != null && !con.isClosed()) {
			con.close();
		}
		if (stat != null && !stat.isClosed()) {
			stat.close();
		}
		if (rs != null && !rs.isClosed()) {
			rs.close();
		}
 
	}

}

JSP页面:

<%@page contentType="text/html; charset=UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>省市联动</title>
</head>

<body onload="listProvince();">
<script type="text/javascript">
   function listProvince(){
	   //发送ajax请求，查询所有的省份，返回json
	   var xmlHttp;
		  if(window.XMLHttpRequest){
			  xmlHttp=new XMLHttpRequest();
		  }else{
			  xmlHttp=new ActiveXObject("Microsoft.XMLHttp");
		  }
		  xmlHttp.onreadystatechange=function(){
			if(xmlHttp.readyState==4){
				if(xmlHttp.status == 200){
					//接收服务端返回的json
				var jsonString=xmlHttp.responseText;
				eval("var arr="+jsonString);
				//遍历数组
				var html="<option value=''>--请选择省份--</option>";
				for(var i=0;i<arr.length;i++){
					 var provinceJson=arr[i];
					 html+="<option value='"+provinceJson.code+"'>"+provinceJson.name+"</option>";
				}
				document.getElementById("provinceList").innerHTML=html;
				}else{
					alert(xmlHttp.status);
				}
			    
			}
		  }
	    var timeStamp=new Date().getTime();
		xmlHttp.open("GET","${pageContext.request.contextPath}/province/list.do",true);//这里只开启通道，不发送请求,为了解决ajax-get请求缓存问题，可以加个时间戳
		//4.通知异步请求对象代替浏览器发送请求协议包
		xmlHttp.send();
   }
   function listCitys(pcode){
	   //发送ajax请求，查询所有的省份，返回json
	   var xmlHttp;
		  if(window.XMLHttpRequest){
			  xmlHttp=new XMLHttpRequest();
		  }else{
			  xmlHttp=new ActiveXObject("Microsoft.XMLHttp");
		  }
		  xmlHttp.onreadystatechange=function(){
			if(xmlHttp.readyState==4){
				if(xmlHttp.status == 200){
					//接收服务端返回的json
				var jsonString=xmlHttp.responseText;
				eval("var arr="+jsonString);
				//遍历数组
				var html="<select><option value=''>--请选择市区--</option>";
				for(var i=0;i<arr.length;i++){
					 var cityJson=arr[i];
					 html+="<option value='"+cityJson.code+"'>"+cityJson.name+"</option>";
				}
				html+="</select>";
				document.getElementById("citySpan").innerHTML=html;
				}else{
					alert(xmlHttp.status);
				}
			    
			}
		  }
	    var timeStamp=new Date().getTime();
		xmlHttp.open("GET","${pageContext.request.contextPath}/city/list.do?_timeStamp="+timeStamp+"&pcode="+pcode,true);//这里只开启通道，不发送请求,为了解决ajax-get请求缓存问题，可以加个时间戳
		//4.通知异步请求对象代替浏览器发送请求协议包
		xmlHttp.send();
   }
</script>
  <select  id="provinceList" onchange="listCitys(this.value);">
  </select>
  <span id="citySpan"></span>
</body>
</html>

省份类:

package com.bjpowernode.pc.web.action;

import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

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

public class ProvinceListAction extends HttpServlet {

	protected void doGet(HttpServletRequest request, HttpServletResponse response) 
			throws ServletException, IOException {
		//局部变量不存在线程安全隐患，所以建议使用StringBuilder,效率较高。
		 
		StringBuilder json=new StringBuilder();
		json.append("[");
		Connection conn=null;
		PreparedStatement ps=null;
		ResultSet rs=null;
		try {
			conn=JdbcUtils.getConnection();
			String sql="select code,name from t_province order by code asc";
			ps=conn.prepareStatement(sql);
			rs=ps.executeQuery();
			while(rs.next()) {
				String code=rs.getString("code");
				String name=rs.getString("name");
				
				json.append("{\"code\":\"");
				json.append(code);
				json.append("\",\"name\":\"");
				json.append(name);
				json.append("\"},");
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}finally {
			try {
				JdbcUtils.close(conn, ps, rs);
			} catch (SQLException e) {
			}
		}
		String endJson=json.substring(0,json.length()-1)+"]";
		response.setContentType("text/html;charset=UTF-8");
		response.getWriter().println(endJson);
	}

}

城市类:

package com.bjpowernode.pc.web.action;

import java.io.IOException;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

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

public class CityListAction extends HttpServlet {
	
	protected void doGet(HttpServletRequest request, HttpServletResponse response) 
			throws ServletException, IOException {
		//局部变量不存在线程安全隐患，所以建议使用StringBuilder,效率较高。
		String pcode=request.getParameter("pcode");
		StringBuilder json=new StringBuilder();
		json.append("[");
		Connection conn=null;
		PreparedStatement ps=null;
		ResultSet rs=null;
		try {
			conn=JdbcUtils.getConnection();
			String sql="select code,name from t_city where pcode=? order by code asc";
			ps=conn.prepareStatement(sql);
			ps.setString(1, pcode);
			rs=ps.executeQuery();
			while(rs.next()) {
				String code=rs.getString("code");
				String name=rs.getString("name");
				
				json.append("{\"code\":\"");
				json.append(code);
				json.append("\",\"name\":\"");
				json.append(name);
				json.append("\"},");
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}finally {
			try {
				JdbcUtils.close(conn, ps, rs);
			} catch (SQLException e) {
			}
		}
		String endJson=json.substring(0,json.length()-1)+"]";
		response.setContentType("text/html;charset=UTF-8");
		response.getWriter().println(endJson);
	}
	}

xml文件:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>pc</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>
    <description></description>
    <display-name>ProvinceListAction</display-name>
    <servlet-name>ProvinceListAction</servlet-name>
    <servlet-class>com.bjpowernode.pc.web.action.ProvinceListAction</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>ProvinceListAction</servlet-name>
    <url-pattern>/province/list.do</url-pattern>
  </servlet-mapping>
  <servlet>
    <description></description>
    <display-name>CityListAction</display-name>
    <servlet-name>CityListAction</servlet-name>
    <servlet-class>com.bjpowernode.pc.web.action.CityListAction</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>CityListAction</servlet-name>
    <url-pattern>/city/list.do</url-pattern>
  </servlet-mapping>
</web-app>