用SSH制作动态无限级关联下拉菜单

最新推荐文章于 2020-05-10 13:32:43 发布

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最新推荐文章于 2020-05-10 13:32:43 发布

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分类专栏： Ajax系列文章标签： ssh null dao struts import bean

本文链接：https://blog.youkuaiyun.com/lenolong/article/details/3506498

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本文介绍了如何使用SSH框架从数据库动态提取字段，创建无限级关联的下拉菜单。通过Category POJO的自身关联，配合Dao和DaoService，实现了根据父Category ID为null查找各级分类。页面部分利用JSTL标签进行迭代，展示一级分类，并通过JS生成二级分类的选项。

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效果图

这几天自己在用SSH做项目来实践前一段实践的学习在最重要的模块里遇到了两个难题

一个就是实现动态的从数据库里提取字段然后产生动态的关联下拉菜单

令一个就是用Struts来实现多文件上传这两个问题折腾了我3天今天终于搞好了一看google的搜索栏

下面有好几百条 ^_^ 还好我都找到了有用的信息

第一个问题的解决

首先是Category这个POJO 是自身关联的

hbm如下

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>

</id>

</property>

<set

name="childCategories"

cascade="save-update"

inverse="true"

<one-to-many class="com.ergal.hibernate.Category" />

</set>

<many-to-one

name="parentCategory"

column="CATEGORY_ID"

class="com.ergal.hibernate.Category"

</class>

</hibernate-mapping>

POJO就不列了主要是Dao和DaoService

先构造一个常用的工具类用来获取bean

package com.ergal.hibernate;

import org.springframework.context.support.AbstractApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class AppContext

{

private static AppContext instance;

private AbstractApplicationContext appContext;

public synchronized static AppContext getInstance()

{

if(instance == null)

{

instance =new AppContext();

}

return instance;

}

private AppContext()

{

this.appContext=new ClassPathXmlApplicationContext("beans-config.xml");

}

public AbstractApplicationContext getAppContext()

{

return appContext;

}

Dao的接口

ICategory.java

package com.ergal.hibernate;

import java.util.List;

public interface ICategory

{

public List getOneCatrgoriesByparentCategoryId(long id);

public List getSubCatrgoriesByparentCategoryId(long id);

public List getSubCatrgoriesBySubCategoryId(long id);

public List getCatrgoriesById(long id);

}

Dao

package com.ergal.hibernate;

import java.util.List;

import org.springframework.orm.hibernate3.support.HibernateDaoSupport;

public class CategoryDao extends HibernateDaoSupport implements ICategory

{

public List getOneCatrgoriesByparentCategoryId(long id)

{

return getHibernateTemplate().find("from Category as c where c.parentCategory.id="+null);

}

public List getSubCatrgoriesByparentCategoryId(long id)

{

return getHibernateTemplate().find("from Category as c where c.parentCategory.parentCategory.id="+null);

}

public List getSubCatrgoriesBySubCategoryId(long id)

{

return getHibernateTemplate().find("from Category as c where c.parentCategory.parentCategory.parentCategory.id="+null);

}

public List getCatrgoriesById(long id)

{

return getHibernateTemplate().find("from Category as c where c.id="+id);

}

因为在页面中没有一个数据是静态的包括最上层的分类也是动态的因为很可能以后对Category的字段重新设置

这样页面就根本不用修改全是动态获取的方法就是查找父Category的ID为null 以此类推

页面部分

还没有做进一步的封装所以有些杂乱

<%@ page language="java" pageEncoding="GBK" import="com.ergal.hibernate.*,java.util.*"%>

<%@ taglib uri="/tags/struts-html" prefix="html"%>

<%@ taglib uri="/tags/struts-bean" prefix="bean"%>

<%@ taglib uri="/tags/c.tld" prefix="c"%>

String path = request.getContextPath();

String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

<title>My JSP 'addpackage.jsp' starting page</title>

</head>

<body>

List resultone=((ICategory)AppContext.getInstance().getAppContext().getBean("categoryDaoProxy"))

.getOneCatrgoriesByparentCategoryId(new Long(0));

int onesize=resultone.size();

Category[] cateone=new Category[onesize];

int ik=0;

for(Iterator it=resultone.iterator(); it.hasNext();)

{

cateone[ik]=(Category)it.next();

ik++;

}

request.setAttribute("cateone", cateone);

List resultmusic=((ICategory)AppContext.getInstance().getAppContext().getBean("categoryDaoProxy"))

.getSubCatrgoriesByparentCategoryId(new Long(1));

int msize=resultmusic.size();

Category[] catemusic=new Category[msize];

int im=0;

for(Iterator it=resultmusic.iterator(); it.hasNext();)

{

catemusic[im]=((Category)it.next());

im++;

}

request.setAttribute("catemuisc", catemusic);

List resultsub=((ICategory)AppContext.getInstance().getAppContext().getBean("categoryDaoProxy"))

.getSubCatrgoriesBySubCategoryId(new Long(1));

int subsize=resultsub.size();

Category[] catesub=new Category[subsize];

int is=0;

for(Iterator it=resultsub.iterator(); it.hasNext();)

{

catesub[is]=((Category)it.next());

is++;

}

request.setAttribute("catesub", catesub);

var onecount;

onecount=0;

submusic = new Array();

for(int i=0; i<msize; i++){

submusic[<%=i%>] = new Array("<%=catemusic[i].getName()%>","<%=catemusic[i].getId()%>","<%=catemusic[i].getParentCategory().getId()%>");

<% } %>

onecount=<%=msize%>;

function changelocation(locationid)

{

document.myform.level2.length = 0;

var locationid=locationid;

var i;

var j=1;

var optb=new Option();

optb.text="二级分类";

document.myform.level2.options[0] = optb;

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

{

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

{

var opt=new Option();

opt.text=submusic[i][0];

opt.value=submusic[i][1];

document.myform.level2.options[j] = opt;

j++;

}

var twocount;

twocount=0;

subsub = new Array();

for(int i=0; i<subsize; i++){

subsub[<%=i%>] = new Array("<%=catesub[i].getName()%>","<%=catesub[i].getId()%>","<%=catesub[i].getParentCategory().getId()%>");

<% } %>

twocount=<%=subsize%>;

function changelocationsub(locationid)

{

document.myform.level3.length = 0;

var locationid=locationid;

var i;

var j=1;

var optb=new Option();

optb.text="三级分类";

document.myform.level3.options[0] = optb;

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

{

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

{

var opt=new Option();

opt.text=subsub[i][0];

opt.value=subsub[i][1];

document.myform.level3.options[j] = opt;

j++;

}

</script>

<hr>

<c:forEach items="${cateone}" var="item">

</c:forEach>

</select>

</select>

</select><br>

</form>

</body>

</html>

用来提取一级的种类并存在request中

List resultone=((ICategory)AppContext.getInstance().getAppContext().getBean("categoryDaoProxy"))

.getOneCatrgoriesByparentCategoryId(new Long(0));

int onesize=resultone.size();

Category[] cateone=new Category[onesize];

int ik=0;

for(Iterator it=resultone.iterator(); it.hasNext();)

{

cateone[ik]=(Category)it.next();

ik++;

}

request.setAttribute("cateone", cateone);

然后用JSTL的标签来迭代

<c:forEach items="${cateone}" var="item">

</c:forEach>

</select>

同理用在获得2级分类的List后用js来产生第二个option

var onecount;

onecount=0;

submusic = new Array();

for(int i=0; i<msize; i++){

submusic[<%=i%>] = new Array("<%=catemusic[i].getName()%>","<%=catemusic[i].getId()%>","<%=catemusic[i].getParentCategory().getId()%>");

<% } %>

onecount=<%=msize%>;

function changelocation(locationid)

{

document.myform.level2.length = 0;

var locationid=locationid;

var i;

var j=1;

var optb=new Option();

optb.text="二级分类";

document.myform.level2.options[0] = optb;

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

{

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

{

var opt=new Option();

opt.text=submusic[i][0];

opt.value=submusic[i][1];

document.myform.level2.options[j] = opt;

j++;

}

var twocount;

twocount=0;

subsub = new Array();

for(int i=0; i<subsize; i++){

subsub[<%=i%>] = new Array("<%=catesub[i].getName()%>","<%=catesub[i].getId()%>","<%=catesub[i].getParentCategory().getId()%>");

<% } %>

twocount=<%=subsize%>;

function changelocationsub(locationid)

{

document.myform.level3.length = 0;

var locationid=locationid;

var i;

var j=1;

var optb=new Option();

optb.text="三级分类";

document.myform.level3.options[0] = optb;

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

{

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

{

var opt=new Option();

opt.text=subsub[i][0];

opt.value=subsub[i][1];

document.myform.level3.options[j] = opt;

j++;

}

</script>

后面的代码就很简单了

</select>

</select><br>

可以以此类推构造更多的动态关联下拉菜单