自己动手写struts实现下拉框多级联动

约束： 必须以id作为下拉框的value， name为下落框的label；

使用方法： 以三级资料类别为例。

jsp页面：

		<tr class="whitebg">
			<td width="15%" height="20" class="gray">文档类型<span class="redStar">*</span></td>
			<td>
			<html:select property="docTypeL1Id"
				onchange="setProperty('docTypeL2Id','');;setProperty('docTypeL3Id','');;refreshPage(this);">
					<option value=""><bean:message key="label.pleaseSelect"	bundle="common" /></option>
				<html:optionsCollection property="docTypeL1Options" />
			</html:select>
			<html:select property="docTypeL2Id"
				onchange="setProperty('docTypeL3Id','');;refreshPage(this);">
				<option value=""><bean:message key="label.pleaseSelect"
					bundle="common" /></option>
				<xxx:dynamicOptions parentProperty="docTypeL1Id"
					sqlModule="module_doc" sqlName="sql_doc_options_doctypel2" />
			</html:select>
			<html:select property="docTypeL3Id"
				onchange="refreshPage(this);">
				<option value=""><bean:message key="label.pleaseSelect"
					bundle="common" /></option>
				<xxx:dynamicOptions parentProperty="docTypeL2Id"
					sqlModule="module_doc" sqlName="sql_doc_options_doctypel3" />
			</html:select></td>
		</tr>

formBean：

	private String docTypeL1Id;
	/**
	 * 一级资料类别下拉框选项列表
	 */
	private ArrayList docTypeL1Options = new ArrayList();;
	private String docTypeL2Id;
	private String docTypeL3Id;

action：

	/**
	 * 跳转到“创建资料步骤一”页面。
	 * 
	 * @param mapping
	 * @param form
	 * @param request
	 * @param response
	 * @return
	 */
	public ActionForward showCreateDocStep1(
		ActionMapping mapping,
		ActionForm form,
		HttpServletRequest request,
		HttpServletResponse response);
		throws Exception {
		DocForm docForm = (DocForm); form;
		DocDelegate docDelegate = new DocDelegate();;

		//设置当前左菜单栏的焦点
		BarFocus.setFocus(request, BarFocus.PW_CREATE_DOC);;
		//进入页面之前需要把第一级资料类别下拉框的数据准备好。
		DocViewHelper.prepareViewHelpData(docForm);;
		return mapping.findForward("createDocStep1");;
	}

	//刷新页面执行的方法， 也可调用showCreateDocStep1
	public ActionForward refreshPage(
		ActionMapping mapping,
		ActionForm form,
		HttpServletRequest request,
		HttpServletResponse response);
		throws Exception {
		DocViewHelper.prepareViewHelpData((DocForm); form);;
		return (mapping.findForward("createDocStep1"););;
	}

SQL.xml:

   <!-- 文档模块 SQL语句 --> 

   <module_doc
    sql_doc_options_doctypel2="SELECT * FROM T_BASE_DOC_TYPE WHERE DOC_TYPE_LEVEL='2' AND PARENT_ID=? ORDER BY NAME ASC"
    sql_doc_options_doctypel3="SELECT * FROM T_BASE_DOC_TYPE WHERE DOC_TYPE_LEVEL='3' AND PARENT_ID=? ORDER BY NAME ASC"
   />