用JSP+JavaScript打造二级级联下拉菜单_jsp创建二级分类页面-优快云博客

本文介绍如何使用JSP与JavaScript技术创建动态二级级联下拉菜单。通过从数据库获取栏目信息并利用JavaScript动态更新选项，实现了根据用户选择的一级栏目自动加载对应的二级栏目。

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JSP+JavaScript打造二级级联下拉菜单：

class(一级栏目信息）：classId(自动编号），className（栏目名称）, Nclass（二级栏目信息）, NclassId（自动编号），NclassName(栏目名称），parentId（一级栏目id，与class表中的classId关联）

<%@ page contentType=text/html;charset=GB2312 language=java errorPage=../error.jsp %>

<%@ include file=../conn.jsp%>

<%@ include file=../ds.jsp%>

<%@ taglib uri=http://java.sun.com/jsp/jstl/sql divfix=sql %>

<%request.setCharacterEncoding(gb2312); %>

<METAhttp-equiv=Content-Type content=text/html; charset=gb2312>

</HEAD>

<%String sql=select* from Nclass order by NclassIdasc;

ResultSet rs=stmt.executeQuery(sql);

var onecount;

onecount=0;

subcat = new Array();

int count = 0;

while(rs.next()){

subcat[<%=count%>] = new Array(<%=rs.getString(NclassName)%>,

<%=rs.getString(NclassId)%>,<%=rs.getString(parentId)%>);

count++;

}

rs.close();

onecount=<%=count%>;

function changelocation(locationid)

{

document.myform.NclassId.length= 0;

var locationid=locationid;

var i;

for(i=0;i < onecount; i++)

{

if (subcat[i][2] == locationid)

{

document.myform.NclassId.options[document.myform.NclassId.length]= new

Option(subcat[i][0], subcat[i][1]);

}

</script>

<TABLE>

<TR>

<TD>

<SELECT name=classId onChange=changelocation(document.myform.classId.options

[document.myform.classId.selectedIndex].value)size=1>

<OPTION selected value>==请选一级分类==</OPTION>

<sql:query var=querydataSource=$>

SELECT * FROM class

</sql:query>

<c:forEachvar=row items=$>

</c:forEach>

</select>

</TD>

<TD>选择二级分类</TD>

<TD>

<OPTION selected value>==请选二级分类==</OPTION>

</SELECT>

</TD>

</TR>

</TABLE>

</FORM>

</BODY>

</HTML>

<%@ page contentType=text/html;charset=GB2312 language=java errorPage=../error.jsp %>

<%@ include file=../conn.jsp%>

<%@ include file=../ds.jsp%>

<%@ taglib uri=http://java.sun.com/jsp/jstl/sql divfix=sql %>

<%request.setCharacterEncoding(gb2312); %>

<METAhttp-equiv=Content-Type content=text/html; charset=gb2312>

</HEAD>

<%String sql=select* from Nclass order by NclassIdasc;

ResultSet rs=stmt.executeQuery(sql);

var onecount;

onecount=0;

subcat = new Array();

int count = 0;

while(rs.next()){

subcat[<%=count%>] = new Array(<%=rs.getString(NclassName)%>,

<%=rs.getString(NclassId)%>,<%=rs.getString(parentId)%>);

count++;

}

rs.close();

onecount=<%=count%>;

function changelocation(locationid)

{

document.myform.NclassId.length= 0;

var locationid=locationid;

var i;

for(i=0;i < onecount; i++)

{

if (subcat[i][2] == locationid)

{

document.myform.NclassId.options[document.myform.NclassId.length]= new

Option(subcat[i][0], subcat[i][1]);

}

</script>

<TABLE>

<TR>

<TD>

<SELECT name=classId onChange=changelocation(document.myform.classId.options

[document.myform.classId.selectedIndex].value)size=1>

<OPTION selected value>==请选一级分类==</OPTION>

<sql:query var=querydataSource=$>

SELECT * FROM class

</sql:query>

<c:forEachvar=row items=$>

</c:forEach>

</select>

</TD>

<TD>选择二级分类</TD>

<TD>

<OPTION selected value>==请选二级分类==</OPTION>

</SELECT>

</TD>

</TR>

</TABLE>

</FORM>

</BODY>

</HTML>