jsp实现连动下拉框.

本文主要是介绍jsp实现连动下拉框.，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

联动下拉选择框，动态获取下一级,根据上一级的条件,显示下一级的内容,这样的好处就是不用一次性从数据库全部读到下拉框,造成内容太多,不太好选择.一级联动知道怎么实现了,多级联动其实也是一样的.这里列出的例子,给大家参考和学习.

联动下拉框,只需要一个JAVA文件,一个JSP文件.

表结构 A,表 id varchar2(10),name varchar2(10)

B 表 id varchar2 ,name varchar2(10)

A表内容: 1 电脑, 2 空调 3 家电

B表内容:1 联想,1 方正,2 海尔, 2 春兰 , 3 LG,3 TCL

MyDbBean.java

import java.sql.*;
public class MyDbBean {
Connection con=null;
public First() {
      Class.forName("oracle.jdbc.driver.OracleDriver").newInstance();
      con=DriverManager
          .getConnection("jdbc:oracle:thin:@127.0.0.1:1521:test",
                                  "dd","dd");
}
public ResultSet executeQuery (String sql) {

    PreparedStatement pstm=null;
    ResultSet rs=null;
    try {
      pstm=con.prepareStatement(sql);
      rs=pstm.executeQuery();
      return rs;
      }
    }catch(SQLException e){
      e.printStackTrace();
      return null;
    }catch (Exception e) {
      e.printStackTrace();
       return null;
    }finally{
      try{
        if(rs!=null)rs.close();
      }catch(Exception e){}
    }
}
}

TEST.JSP

<%@ page contentType="text/html; charset=GBK" %>
<%@ page import="DataBase.*" %>
<%@ page import="java.sql.*" %>
<%! MyDbBean bean = new MyDbBean();%>
<html>
<head>
<title>
test
</title>
</head>
<body bgcolor="#ffffff">
<form method="post">
<select name="dl" onChange="javascript:window.location=(this.options[this.selectedIndex].value1)">
<%
String id = request.getParameter("id");

   String cSql = "select * from a";
   ResultSet sqlRst=bean.executeQuery(cSql);
   try
   {
   while(sqlRst.next())
   {
   String i = sqlRst.getString("id");
   String name = sqlRst.getString("name");
   if(id == null) id="1";
if (id.equals(i))
             {
                 String temp="./test.jsp?id="+i+"&name="+name;
                 out.println("<option value="+i+" value1="+temp+" selected>"+name+"</option>");
             }
            else
            {
                 String temp="./test.jsp?id="+i+"&name="+name;
                 out.println("<option value="+i+" value1="+temp+">"+name+"</option>");
             }
        }
    }catch(Exception e)
    {}
%>
</select>
<select name="dl">
<%
    String Csql = null;
    if (id == null)
    {
        Csql="select * from b where id = 1";
    }
    else
    {
        Csql="select * from b where id =" +id ;
    }
    sqlRst=bean.executeQuery(Csql);
    try{
       while(sqlRst.next())
         {
             String i = sqlRst.getString("id");
             String name = sqlRst.getString("name");
             if (id.equals(i))
             {
                 String temp="./test.jsp?id="+i+"&name="+name;
                 out.println("<option value="+i+" value1="+temp+" selected>"+name+"</option>");
             }
            else
            {
                 String temp="./test.jsp?id="+i+"&name="+name;
                 out.println("<option value="+i+" value1="+temp+">"+name+"</option>");
             }
          }
        }catch(Exception e)
        {
        }
%>
</select>