浅谈“三层结构”原理与用意 3
postlword.aspx页面文件（发送留言到数据库）
#001 <%@ page language="c#" codebehind="postlword.aspx.cs" autoeventwireup="false"
inherits="tracelword1.postlword" %>
#002 <!doctype html public "-//w3c//dtd html 4.0 transitional//en">
#003
#004 <html>
#005 <head>
#006 <title>postlword</title>
#007 <meta name="generator" content="microsoft visual studio .net 7.1">
#008 <meta name="code_language" content="c#">
#009 <meta name=vs_defaultclientscript content="javascript">
#010 <meta name=vs_targetschema content="http://schemas.microsoft.com/intellisense/ie5">
#011 </head>
#012 <body ms_positioning="gridlayout">
#013
#014 <form id="__aspnetform" method="post" runat="server">
#015
#016 <textarea id="m_txtcontent" runat="server" rows=8 cols=48></textarea>
#017 <input type="button" id="m_btnpost" runat="server" value="发送留言" />
#018
#019 </form>
#020
#021 </body>
#022 </html>
postlword.aspx后台程序文件postlword.aspx.cs
#001 using system;
#002 using system.collections;
#003 using system.componentmodel;
#004 using system.data;
#005 using system.data.oledb; // 需要操作 access 数据库
#006 using system.drawing;
#007 using system.web;
#008 using system.web.sessionstate;
#009 using system.web.ui;
#010 using system.web.ui.webcontrols;
#011 using system.web.ui.htmlcontrols;
#012
#013 namespace tracelword1
#014 {
#015 /// <summary>
#016 /// postlword 发送留言到数据库
#017 /// </summary>
#018 public class postlword : system.web.ui.page
#019 {
#020 // 留言内容编辑框
#021 protected system.web.ui.htmlcontrols.htmltextarea m_txtcontent;
#022 // 提交按钮
#023 protected system.web.ui.htmlcontrols.htmlinputbutton m_btnpost;
#024
#025 /// <summary>
#026 /// postlword.aspx 页面加载函数
#027 /// </summary>
#028 private void page_load(object sender, system.eventargs e)
#029 {
#030 }
#031
#032 #region web 窗体设计器生成的代码
#033 override protected void oninit(eventargs e)
#034 {
#035 initializecomponent();
#036 base.oninit(e);
#037 }
#038
#039 private void initializecomponent()
#040 {
#041 this.load+=new system.eventhandler(this.page_load);
#042 this.m_btnpost.serverclick+=new eventhandler(post_serverclick);
#043 }
#044 #endregion
#046 /// <summary>
#047 /// 发送留言信息到数据库
#048 /// </summary>
#049 private void post_serverclick(object sender, eventargs e)
#050 {
#051 // 获取留言内容
#052 string textcontent=this.m_txtcontent.value;
#053
#054 // 留言内容不能为空
#055 if(textcontent=="")
#056 throw new exception("留言内容为空");
#057
#058 string mdbconn=@"provider=microsoft.jet.oledb.4.0; data source=c:\dbfs\tracelworddb.mdb";
#059 string cmdtext="insert into [lword]([textcontent]) values(@textcontent)";
#060
#061 oledbconnection dbconn=new oledbconnection(mdbconn);
#062 oledbcommand dbcmd=new oledbcommand(cmdtext, dbconn);
#063
#064 // 设置留言内容
#065 dbcmd.parameters.add(new oledbparameter("@textcontent",
oledbtype.longvarwchar));
#066 dbcmd.parameters["@textcontent"].value=textcontent;
#067
#068 try
#069 {
#070 dbconn.open();
#071 dbcmd.executenonquery();
#072 }
#073 catch
#074 {
#075 throw;
#076 }
#077 finally
#078 {
#079 dbconn.close();
#080 }
#081
#082 // 跳转到留言显示页面
#083 response.redirect("listlword.aspx", true);
#084 }
#085 }
#086 }
仅仅通过两个页面，就完成了一个基于access数据库的留言功能。
程序并不算复杂，非常简单清楚。但是随后你会意识到其存在着不灵活性！
