package com.hanqi.entity;

//地区
public class Region {
    
    //地区id
    private String regionID;
    //地区名称
    private String regionName;

    //上级地区id
    private String parentRegionID;
    
    public String getRegionID() {
        return regionID;
    }

    public void setRegionID(String regionID) {
        this.regionID = regionID;
    }

    public String getRegionName() {
        return regionName;
    }

    public void setRegionName(String regionName) {
        this.regionName = regionName;
    }

    public String getParentRegionID() {
        return parentRegionID;
    }

    public void setParentRegionID(String parentRegionID) {
        this.parentRegionID = parentRegionID;
    }

    public Region(String regionID, String regionName, String parentRegionID) {
        super();
        this.regionID = regionID;
        this.regionName = regionName;
        this.parentRegionID = parentRegionID;
    }

    public Region() {
        super();
    }

    @Override
    public String toString() {
        return "Region [regionID=" + regionID + ", regionName=" + regionName + ", parentRegionID=" + parentRegionID
                + "]";
    }

    

}

package com.hanqi.dao;

import java.util.ArrayList;
import java.util.List;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;

import com.hanqi.entity.Region;

public class RegionDAO {

    Configuration cfg = null;
    ServiceRegistry sr = null;
    SessionFactory sf =null;
    Session se = null;
    Transaction tr = null;

    public RegionDAO()
    {
        //加载配置文件
        cfg = new Configuration().configure();
        //注册服务
        sr =new StandardServiceRegistryBuilder()
                .applySettings(cfg.getProperties()).build();
        
    }
    
    private void init()
    {
        
        sf = cfg.buildSessionFactory(sr);
        se =sf.openSession();
        tr=se.beginTransaction();
        
    }
    private void destroy()
    {
        tr.commit();
        se.close();
        sf.close();
    }
    //获取数据列表
    public List<Region> getList(String parentid)
    {
        List<Region> rtn = new ArrayList<Region>();
        
        init();
        
        //查询数据
        rtn = se.createQuery("from Region where parentRegionID="+parentid).list();
        
        
        destroy();
        
        return rtn;
    }
}

package com.hanqi.service;

import java.util.List;

import com.hanqi.dao.RegionDAO;
import com.hanqi.entity.Region;

public class RegionService {

    public List<Region> getList(String parentid){
        return new RegionDAO().getList(parentid);
    }
}

package com.hanqi.servlet;

import java.io.IOException;
import java.util.List;

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

import com.alibaba.fastjson.JSONArray;
import com.hanqi.entity.Region;
import com.hanqi.service.RegionService;

/**
 * Servlet implementation class RegionServlet
 */
public class RegionServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public RegionServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {


        request.setCharacterEncoding("UTF-8");
        response.setCharacterEncoding("UTF-8");

        response.setContentType("text/html");
        //接收参数
        String parentid=request.getParameter("parentid");
        if(parentid!=null)
        {
        //读取地区列表
        List<Region> lr = new RegionService().getList(parentid);
        
        //返回JSON格式的数据 
        String json=JSONArray.toJSONString(lr);
        response.getWriter().print(json);
        }
        else
        {
            response.getWriter().print("[]");

        }
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(request, response);
    }

}

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<!-- 1jQuery的js包 -->
<script type="text/javascript" src="http://www.mamicode.com/jquery-easyui-1.4.4/jquery.min.js"></script>
<!-- 2css资源 -->
<link rel="stylesheet" type="text/css" href="http://www.mamicode.com/jquery-easyui-1.4.4/themes/default/easyui.css">   
<!-- 3图标资源 -->
<link rel="stylesheet" type="text/css" href="http://www.mamicode.com/jquery-easyui-1.4.4/themes/icon.css">   
<!-- 4easyui的js包 -->
<script type="text/javascript" src="http://www.mamicode.com/jquery-easyui-1.4.4/jquery.easyui.min.js"></script>   
  <!-- 5本地语言包 -->
<script type="text/javascript" src="http://www.mamicode.com/jquery-easyui-1.4.4/locale/easyui-lang-zh_CN.js"></script>

</head>
<body>
修改
<input class="easyui-combobox" data-options=
"url:‘json/combo.json‘,
valueField:‘id‘,
textField:‘text‘,
editable:false" >

<br>
<br>
省：<input id="sheng" class="easyui-combobox" style="width: 100px" data-options="
url:‘RegionServlet?parentid=0‘,
valueField:‘regionID‘,
textField:‘regionName‘,
onSelect:function(region){
    //alert(‘选择了省‘+region.regionID)
$(‘#shi‘).combobox(‘clear‘);  //清除原有显示内容
//重新加载
$(‘#shi‘).combobox(‘reload‘,‘RegionServlet?parentid=‘+region.regionID);
$(‘#quxian‘).combobox(‘clear‘);  //清除原有显示内容
$(‘#quxian‘).combobox(‘reload‘,‘RegionServlet‘);//清除下拉项目


}
" >
市：<input id="shi" class="easyui-combobox" style="width: 100px" data-options="
url:‘RegionServlet‘,
valueField:‘regionID‘,
textField:‘regionName‘,
onSelect:function(region){
    alert(‘选择了市‘+region.regionID)
$(‘#quxian‘).combobox(‘clear‘);  //清楚原有项目
//重新加载
$(‘#quxian‘).combobox(‘reload‘,‘RegionServlet?parentid=‘+region.regionID);
}
" >
区县：<input id="quxian" class="easyui-combobox" style="width: 100px" data-options="
url:‘RegionServlet‘,
valueField:‘regionID‘,
textField:‘regionName‘
" >


</body>
</html>