二级联动查询数据库到下拉框

最新推荐文章于 2021-05-24 11:28:07 发布

handsome_happy

最新推荐文章于 2021-05-24 11:28:07 发布

阅读量6.8k

点赞数 1

CC 4.0 BY-SA版权

分类专栏： java selrvlet

本文链接：https://blog.youkuaiyun.com/qq_32201847/article/details/51760159

java selrvlet 专栏收录该内容

3 篇文章

订阅专栏

本文介绍如何利用JSP和Servlet技术实现二级联动的效果，通过从数据库查询数据填充下拉菜单，为用户提供更丰富的筛选选项。内容涵盖了JSP页面的交互逻辑和Servlet后台的数据库操作过程。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

Jsp：

<%@ page language="java" contentType="text/html; charset=GB2312" import="java.sql.*,java.util.*,publicUse.*,com.web.*" errorPage=""
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<%
	String path = request.getContextPath();
	String basePath = request.getScheme() + "://"
			+ request.getServerName() + ":" + request.getServerPort()
			+ path + "/";
%>
<head>
<style type="text/css">
body{
    background:url(../image/abc.gif);
}
</style>
<script type="text/javascript">
        var xmlHttp=false;
        function createXMLHttpRequest()
        {
            if(window.XMLHttpRequest)
            {
                xmlHttp=new XMLHttpRequest();
                }
            else if(window.ActiveXObject)
                xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
            if(xmlHttp==false)
                alert("创建XMLHttpRequest对象失败");
        }
        function updateCity()
        {
            var province=encodeURI(encodeURI(document.all.province.value));
            createXMLHttpRequest();
            xmlHttp.onreadystatechange=processor;
            xmlHttp.open("POST","<%=basePath%>servlet/City?province="+province);
            xmlHttp.send(null);
        }
        function processor()
        {
            var cities;
            if(xmlHttp.readyState==4)//response successfully
            {
                if(xmlHttp.status==200)//return successfully
                {
                    cities=xmlHttp.responseXML.getElementsByTagName("city");
                     
                    while(document.all.city.options.length>0)
                    {
                        document.all.city.removeChild(document.all.city.childNodes[0]);
                    }
                }
             
                for(var i=0;i<cities.length;i++)
                {
                     
                    var option=document.createElement("OPTION");
                     
                    option.text=cities[i].getElementsByTagName("cityname")[0].firstChild.data;
                    //alert(option.text);
                    option.value=cities[i].getElementsByTagName("cityvalue")[0].firstChild.data;
                    document.all.city.options.add(option);
                }
            }
        }
     
    </script>
    <script language="javascript">

function check(){
	for ( var i = 0; i < 2; i++) {
		if (form.elements[i].value == "") {
			alert("选择数据!");
			return false;
		}
	}
                   if(window.confirm("确定要删除选中数据吗？")){
                      return true;
                   }
                   else{
                      return false;
                   }
    }

</script>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
<%
	  DBConnect connect = new DBConnect();
	String GetInfoSql = "select distinct gsname from caiwu";
 	 System.out.println(GetInfoSql);
	  ResultSet rs = connect.executeQuery(GetInfoSql);
%>
	<form name="form" method="post" action="<%=basePath%>servlet/DbDel"  onSubmit="return  check()">
	<p> </p>
	<p> </p>
	<table width="50%"  align="center" cellpadding="1" cellspacing="0">
	    <tr><td width="5%" nowrap="nowrap"><div align="right"><span class="STYLE2">选择公司：</span></div></td>
	      <td width="10%" align="right">
	      <select name="select" id="province" onChange="updateCity();">
            <option  value="">请选择</option>
            <%try{
 	      while(rs.next()){
		   %>
            <option  value=<%=rs.getString("gsname")%>><%=rs.getString("gsname")%></option>
            <%
		 }
 	        rs.close();
			}
			catch(SQLException ex){}
			%>
          </select></td>
          
	      <td width="10%" align="right">选择报表：</td>
	      <td width="10%" align="right">
            <select id="city" name="time">
                <option value="">请选择</option>
            </select>
  	  </td>
   	     <tr><td></td>
   	       <td align="right"><input name="deldb" type="submit" value="删除数据"/></td>
   	       <td align="right"> </td>
         <td align="right"> </td></tr>
  	</table>
	</form>
</body>

</html>

selrvlet:

package com.web;

import java.io.IOException;
import java.io.PrintWriter;
import java.net.URLDecoder;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import publicUse.DBConnect;
import java.sql.ResultSet;
import java.sql.SQLException;
 

public class City extends HttpServlet {

		public void destroy() {
		super.destroy(); 
		// Put your code here
	}

		public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		doPost(request,response);
	}
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/xml");
		response.setCharacterEncoding("UTF-8");
		String province= URLDecoder.decode(request.getParameter("province"), "UTF-8");
		PrintWriter out = response.getWriter();
		out.println("<response>");
		DBConnect connect = new DBConnect();
		Boolean a;
		String GetInfoSql;
		try { 
			 int num=Integer.valueOf(province);//把字符串强制转换为数字 
			 a= false;//如果是数字，返回True 
			 } catch (Exception e) { 
			 a= true;//如果抛出异常，返回False 
			 } 
		if(a){
		GetInfoSql = "select time from caiwu WHERE gsname = '"+province+"'";
		}else{
		GetInfoSql = "select gsname from caiwu WHERE time = '"+province+"'";
		}
		System.out.println(GetInfoSql);
		ResultSet rs = connect.executeQuery(GetInfoSql);
		try{
	 	      while(rs.next()){
	 	    	 String abc;
	 	    	  if(a){
	 	    	abc = rs.getString("time");
	 	 		}else{
		 	    	abc = rs.getString("gsname");
	 	 		}
	 	 		System.out.println(abc);
	 	    	out.println("<city>");
				out.println("<cityname>"+abc+"</cityname>");
				out.println("<cityvalue>"+abc+"</cityvalue>");
				out.println("</city>");
	 	      }
		}			catch(SQLException ex){}

		out.println("</response>");
		
		out.flush();
		out.close();
	}

	public void init() throws ServletException {
		// Put your code here
	}

}