Date:2009.05.07
Problem:
(1) 利用DWR實現三層級聯：函數實現，但是無法將js中的object對象轉換為使用者自訂的對象VideoCateroy
(2)實現JSP頁面的查詢操作：如何將JS返回的str用於SQL語句
一、利用DWR實現三層級聯
1、預期實現結構分析
七年級
---上學期
-------語文
-------數學
-------英語
---下學期
-------語文
-------數學
-------英語
2、編寫Java類：getChildCategoryByParentId(int id)
package com.gslsoft.dao;<br />/*通過父類Id尋找子類目*/<br />@SuppressWarnings("finally")<br />public List<VideoCategory> getChildCategoryByParentId(int id)<br />{<br />String sql="select * from video_category where parentId='"+id+"'";<br />List<VideoCategory> list=new ArrayList();<br />VideoCategory Category=null;<br />try{<br />CachedRowSet rs = DBConnection.getResultSet(sql);<br />while(rs.next()) {<br />Category= new VideoCategory();<br />Category.setName(rs.getString("name"));<br />Category.setRemark(rs.getString("remark"));<br />Category.setLevel(rs.getInt("level"));<br />Category.setImage(rs.getString("image"));<br />Category.setCategoryId(rs.getInt("id"));<br />list.add(Category);<br />}<br />rs.close();<br />} catch (java.sql.SQLException e) {<br />Logger.log(Logger.ERROR,<br />"DataRepository_getVideoFileByCategoryId: with CategoryId=" + id);<br />Logger.log(Logger.ERROR, e.toString());<br />} finally {<br />return list;<br />}<br />}
3、編寫WEB-INF/dwr.xml:具體的配置說明在前面一章給出了詳細的說明
<?xml version="1.0" encoding="GBK"?><br /><dwr><br /> <allow><br /><create creator="new" javascript="videocategoryservice"><br /> <param name="class" value="com.gslsoft.service.VideoCategoryService" /><br /></create><br /> </allow><br /></dwr></p><p>
4、編寫Test.jsp頁面
<%@ page language="java" contentType="text/html; charset=GBK" pageEncoding="GBK"%><br /><%@ taglib uri="http://java.sun.com/jstl/core" prefix="c"%><br /><%@ page import="java.util.*" %><br /><%@ page import="com.gslsoft.service.*" %><br /><%@ page import="com.gslsoft.model.*" %><br /><html><br /><head><br /><title>檔案上傳</title><br /><link rel="stylesheet" href="../../css/x_css1.css" mce_href="css/x_css1.css" type="text/css"><br /><mce:script type='text/javascript' src="/app/dwr/interface/videocategoryservice.js" mce_src="app/dwr/interface/videocategoryservice.js"></mce:script><br /><mce:script type='text/javascript' src="/app/dwr/interface/VideoCategory.js" mce_src="app/dwr/interface/VideoCategory.js"></mce:script><br /><mce:script type='text/javascript' src="/app/dwr/engine.js" mce_src="app/dwr/engine.js"></mce:script><br /><mce:script type='text/javascript' src="/app/dwr/util.js" mce_src="app/dwr/util.js"></mce:script><br /><mce:script type='text/javascript'><!--<br />//根據年級id擷取上下學期<br />function queryterm()<br />{<br /> //var gradeid=$("selectgrade").value;<br /> var gradeid=window.document.getElementById("selectgradea").value;<br /> //預設不選擇<br /> if(gradeid==0)<br /> {<br /> window.document.getElementById("selectterma").options.length=0;<br /> window.document.getElementById("selectsubjecta").options.length=0;<br /> }<br /> else<br /> {<br /> videocategoryservice.getChildCategoryByParentId(gradeid,termCallBack);<br /> }<br />}</p><p>function termCallBack(data)<br />{<br /> window.document.getElementById("selectterma").options.length=0;</p><p> for(var i=0;i< data.length;i ++){<br /> alert(data.length);<br /> alert(typeof(data[i]));<br /> var value =videocategoryservice.ConvertVideoCategory(data[i]).getCategoryId();<br /> var text=videocategoryservice.ConvertVideoCategory(data[i]).getName();<br /> var option = new Option(text, value);<br /> //根據每組value和text標記的值建立一個option對象<br /> try{<br /> window.document.getElementById("selectterma").options.add(option);//將option對象添加到第二個下拉框中<br /> }catch(e){<br /> }<br /> }</p><p> var termid = window.document.getElementById("selectterma").value;<br /> alert(termid);<br /> videocategoryservice.getChildCategoryByParentId(termid,subjectCallBack);</p><p>}</p><p>function querysubject()<br />{<br /> var termid = window.document.getElementById("selectterma").value;<br /> videocategoryservice.getChildCategoryByParentId(termid,subjectCallBack);<br />}</p><p>function subjectCallBack(VideoCategory)<br />{<br /> window.document.getElementById("selectsubjecta").options.length=0;<br /> for(var i=0;i< VideoCategory.length;i ++){<br /> // var value = VideoCategory[i].categoryId;<br /> //var text = VideoCategory[i].name;<br /> var option = new Option("text", "value");<br /> //根據每組value和text標記的值建立一個option對象<br /> try{<br /> window.document.getElementById("selectsubjecta").options.add(option);//將option對象添加到第三個下拉框中<br /> }catch(e){<br /> }<br /> }<br />}</p><p>function change1()<br />{<br /> queryterm();<br />}</p><p>function change2()<br />{<br />querysubject();<br />}<br />// --></mce:script><br /></head><br /><body><br /><p> </p><br /><FORM METHOD="POST" ACTION="UploadM.jsp" ENCTYPE="multipart/form-data"><br /> <table id="Table1" bgcolor="#e1efcb" border="0" cellpadding="4" cellspacing="0" style="width: 100%"><br /><tbody><br /> <tr><br /> <td bgcolor="#f7f7f7" style="width: 80px"><br /> 類目選擇：</td><br /> <td colspan="5"><br /> <%<br />List<VideoCategory> listgrade,listterm,listsubject;<br />VideoCategoryService service1=new VideoCategoryService();<br />listgrade=service1.GetVideoCategoryByLevelID(1);<br />//listterm=service1.w_getChildCategoryByParentId(Integer.parseInt(request.getParameter("selectgrade")));<br />listsubject=service1.GetVideoCategoryByLevelID(3);<br />%><br /><select name="selectgradea" style="width:120px" onchange="queryterm();"><br /><option selected="selected" value="0"><br />請選擇年級...<br /></option><br /><%<br />for(int i=0;i<listgrade.size();i++)<br />{<br />%><br /><option value="<%=listgrade.get(i).getCategoryId()%>"><%=listgrade.get(i).getName()%></option><br /><%<br />}<br />%><br /><%<br />listterm=service1.getChildCategoryByParentId(3);<br />%><br /></select><br /><select name="selectterma" style="width:120px" onchange="querysubject();"><br /><option selected="selected" value="0"><br />請選擇學期...<br /></option><br /></select><br /><select name="selectsubjecta" style="width:120px" onchange=""><br /><option selected="selected" value="0"><br />請選擇科目...<br /></option><br /></select><br /></td><br /></tr><br /></tbody><br /></table><br /></FORM><br /></body><br /></html>
5、運行出現錯誤
6、問題所在：
如何將data[i]的類型object轉換為使用者自訂的VideoCategory類型？
7、解決方案
（1）在dwr.xml加入：
//VideoCategory表示使用者自訂的類型
<convert converter="bean" match="com.gslsoft.model.VideoCategory" />
（2）jsp頁面直接使用
data[i].id取得其id屬性，而不要使用getid()方法來調用其屬性
--------------------------------------------
到此為止，利用dwr解決三層級聯的問題已經全部解決。
二、實現JSP查詢
1、通過條件判斷搜尋索引鍵
alert("查詢條件為：where categoryid='"+window.document.getElementById("selectsubject1").value+"'");
2、寫java 類：
public List<VideoFile> GetAllvideoFileinfowithKey(String key,int start,int limit)
3、問題所在：
如何將搜尋索引鍵作為參數傳送給java類作為參數？
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