AJAX省市县三级联动的实现
省市县数据
本例子中省市县数据保存在MySQL数据库中,部分数据截图如下:
从数据库中读取数据
1、导入需要的jar包
2、连接池配置文件
<c3p0-config> <!-- 默认配置，如果没有指定则使用这个配置 --> <default-config> <property name="driverClass">com.mysql.jdbc.Driver</property> <property name="jdbcUrl">jdbc:mysql://127.0.0.1:3306/test</property> <property name="user">root</property> <property name="password">数据库密码</property> <property name="checkoutTimeout">30000</property> <property name="idleConnectionTestPeriod">30</property> <property name="initialPoolSize">10</property> <property name="maxIdleTime">30</property> <property name="maxPoolSize">100</property> <property name="minPoolSize">10</property> <property name="maxStatements">200</property> <user-overrides user="test-user"> <property name="maxPoolSize">10</property> <property name="minPoolSize">1</property> <property name="maxStatements">0</property> </user-overrides> </default-config> </c3p0-config>
3、JDBCUtils工具类文件
通用JDBCUtils工具类文件,使用时直接引入
package org.xueyao.ajax.utils;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import javax.sql.DataSource;
import org.apache.tomcat.jni.Thread;
import com.mchange.v2.c3p0.ComboPooledDataSource;
public class JDBCUtils {
private static ComboPooledDataSource comboPooledDataSource = new ComboPooledDataSource();
//使用ThreadLocal存取删链接对象
private static ThreadLocal<Connection> local = new ThreadLocal<>();
public static Connection getConnection() throws SQLException{
return comboPooledDataSource.getConnection();
}
public static DataSource getDataSource(){
return comboPooledDataSource;
}
//从ThreadLocal获取链接的方法
public static Connection getCurrentConnection() throws SQLException{
//先从ThreadLocal获取中
Connection connection = local.get();
if(connection != null){
System.out.println("从local获取数据："+connection);
return connection;
}else{
//如果没有，在从链接池获取，存入ThreadLocal中
Connection conn = comboPooledDataSource.getConnection();
System.out.println("从连接池获取数据："+conn);
local.set(conn);
return conn;
}
}
//开启事务的方法
public static void startTransaction() throws SQLException{
Connection connection = getCurrentConnection();
System.out.println(connection);
connection.setAutoCommit(false);
}
//提交事务的方法
public static void commit() throws SQLException{
Connection connection = getCurrentConnection();
System.out.println(connection);
connection.commit();
}
//回滚事务的方法
public static void rollback() throws SQLException{
Connection connection = getCurrentConnection();
System.out.println(connection);
connection.rollback();
}
//释放资源的方法
public static void close() throws SQLException{
Connection connection = getCurrentConnection();
System.out.println(connection);
local.remove();
connection.close();
}
}4、创建JavaBean文件
package org.xueyao.ajax.domain;
public class Province {
private int codeid;
private int parentid;
private String cityName;
public int getCodeid() {
return codeid;
}
public void setCodeid(int codeid) {
this.codeid = codeid;
}
public int getParentid() {
return parentid;
}
public void setParentid(int parentid) {
this.parentid = parentid;
}
public String getCityName() {
return cityName;
}
public void setCityName(String cityName) {
this.cityName = cityName;
}
@Override
public String toString() {
return "Province [codeid=" + codeid + ", parentid=" + parentid
+ ", cityName=" + cityName + "]";
}
}5、创建Servlet文件,获取省市县数据
package org.xueyao.ajax.linkage;
import java.io.IOException;
import java.sql.SQLException;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.dbutils.QueryRunner;
import org.apache.commons.dbutils.handlers.BeanListHandler;
import org.xueyao.ajax.domain.Province;
import org.xueyao.ajax.utils.JDBCUtils;
import flexjson.JSONSerializer;
public class GetDataServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
int parentid = Integer.parseInt(request.getParameter("parentid"));
String sql = "SELECT * FROM province WHERE parentid=?";
QueryRunner qr = new QueryRunner(JDBCUtils.getDataSource());
try {
List<Province> list = qr.query(sql, new BeanListHandler<Province>(Province.class), parentid);
//System.out.println(list);
//将list集合转换成json格式字符串
JSONSerializer jsonSerializer = new JSONSerializer();
String serialize = jsonSerializer.serialize(list);
//System.out.println(serialize);
//向页面输入字符串数据
response.setContentType("text/html;charset=utf-8");
response.getWriter().write(serialize);
} catch (SQLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}6、从页面显示三级联动
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<c:set var="root" value="${pageContext.request.contextPath }"></c:set>
<!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>省市县页面</title>
<script type="text/javascript" src="js/jquery-1.8.3.js"></script>
<script type="text/javascript">
$(function() {
//获得三个下拉菜单元素
var $pro = $("#province");
var $city = $("#city");
var $area = $("#area");
$.get(
"${root}/getData?parentid=0",
function(data) {
//alert(data);
//遍历数据
$(data).each(function(){
//创建option标签,并追加到省级菜单中
$pro.append("<option value='"+this.codeid+"'>"+this.cityName+"</option>");
});
},"json");
//省级菜单选择事件
$pro.change(function(){
//清空市县菜单中数据,保留第一个属性
$city.prop("length",1);
$area.prop("length",1);
$.get(
"${root}/getData?parentid="+this.value,
function(data) {
$(data).each(function() {
$city.append("<option value='"+this.codeid+"'>"+this.cityName+"</option>");
});
},"json");
});
//市级菜单选择事件
$city.change(function(){
//清空县菜单中数据,保留第一个属性
$area.prop("length",1);
$.get(
"${root}/getData?parentid="+this.value,
function(data) {
$(data).each(function(){
$area.append("<option value='"+this.codeid+"'>"+this.cityName+"</option>");
});
},"json");
});
});
</script>
</head>
<body>
<center>
<select id="province" name="province">
<option value="none">--请选择省--</option>
</select>
<select id="city" name="city">
<option value="none">--请选择市--</option>
</select>
<select id="area" name="area">
<option value="none">--请选择县--</option>
</select>
</center>
</body>
</html>上面的javascript代码可以优化成这样
function loadData(value, ele){
$.get(
"${root}/getData?parentid="+value,
function(data) {
//遍历数据
$(data).each(function(){
//创建option标签,追加到菜单中
ele.append("<option value='"+this.codeid+"'>"+this.cityName+"</option>");
});
},"json");
}
$(function() {
var $pro = $("#province");
//加载省和直辖市数据
loadData(0,$pro);
//加载市
$("#city,#area").change(function () {
// 清空原来的数据
$(this).nextAll().prop("length",1);
loadData(this.value, $(this).next());
});
});效果图如下:
