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                        <h1 id="divCurrentNode" style="color: #b83507; width: 100%; text-align: left; font-size: 12px; padding-left: 2px">当前章节:<a href='100162735.htm'><font color='red'>1.6  用C#创建.NET应用程序</font></a></h1>
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                        <div style='float:left;width:49%'>·<a href='100162732.htm'>1.3  中间语言</a></div><div style='float:right;width:49%'>·<a href='100162733.htm'>1.4  程序集</a></div><div style='float:left;width:49%'>·<a href='100162734.htm'>1.5  .NET Framework类</a></div><div style='float:right;width:49%'>·<a href='100162736.htm'>1.7  C#在.NET企业体系结构中的作用</a></div><div style='float:left;width:49%'>·<a href='100162737.htm'>1.8  小结</a></div><div style='float:right;width:49%'>·<a href='100162738.htm'>2.1  引言</a></div></div>
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                <div id="text"> <link href="css.css" rel="stylesheet" type="text/css" /><p class="MsoNormal"><span style="FONT-FAMILY: 宋体">可以用于创建控制台应用程序：仅使用文本、运行在</span><span lang="EN-US">DOS</span><span style="FONT-FAMILY: 宋体">窗口中的应用程序。在进行单元测试类库、创建</span><span lang="EN-US">Unix/Linux daemon</span><span style="FONT-FAMILY: 宋体">进程时，就要使用控制台应用程序。但是，我们常常使用</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">创建利用许多与</span><span lang="EN-US">.NET</span><span style="FONT-FAMILY: 宋体">相关的技术的应用程序，下面简要论述可以用</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">创建的不同类型的应用程序。</span></p>
<h3 style="MARGIN: 8.15pt 0cm"><span lang="EN-US">1.6.1</span><span lang="EN-US">&nbsp; </span><span style="FONT-FAMILY: 黑体">创建</span><span lang="EN-US">ASP.NET</span><span style="FONT-FAMILY: 黑体">应用程序</span></h3>
<p class="MsoNormal" style="LINE-HEIGHT: 16pt"><span lang="EN-US" style="BACKGROUND: aqua"></span><span lang="EN-US">ASP</span><span style="FONT-FAMILY: 宋体">是用于创建带有动态内容的</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">页面的一种</span><span lang="EN-US">Microsoft</span><span style="FONT-FAMILY: 宋体">技术。</span><span lang="EN-US">ASP</span><span style="FONT-FAMILY: 宋体">页面基本是一个嵌有服务器端</span><span lang="EN-US">VBScript</span><span style="FONT-FAMILY: 宋体">或</span><span lang="EN-US">JavaScript</span><span style="FONT-FAMILY: 宋体">代码块的</span><span lang="EN-US">HTML</span><span style="FONT-FAMILY: 宋体">文件。当客户浏览器请求一个</span><span lang="EN-US">ASP</span><span style="FONT-FAMILY: 宋体">页面时，</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">服务器就会发送页面的</span><span lang="EN-US">HTML</span><span style="FONT-FAMILY: 宋体">部分，并处理服务器端脚本。这些脚本通常会查询数据库的数据，在</span><span lang="EN-US">HTML</span><span style="FONT-FAMILY: 宋体">中标记数据。</span><span lang="EN-US">ASP</span><span style="FONT-FAMILY: 宋体">是客户建立基于浏览器的应用程序的一种便利方式。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 16pt"><span style="FONT-FAMILY: 宋体">也有缺点。首先，</span><span lang="EN-US">ASP</span><span style="FONT-FAMILY: 宋体">页面有时显示得比较慢，因为服务器端代码是解释性的，而不是编译的。第二，</span><span lang="EN-US">ASP</span><span style="FONT-FAMILY: 宋体">文件很难维护，因为它不是结构化的，服务器端的</span><span lang="EN-US">ASP</span><span style="FONT-FAMILY: 宋体">代码和一般的</span><span lang="EN-US">HTML</span><span style="FONT-FAMILY: 宋体">会混合在一起。第三，</span><span lang="EN-US">ASP</span><span style="FONT-FAMILY: 宋体">有时开发起来会比较困难，因为它不支持错误处理和语法检查。特别是如果使用</span><span lang="EN-US">VBScript</span><span style="FONT-FAMILY: 宋体">，并希望在页面中进行错误处理，就必须使用</span><span class="codeintext-PRODUCTION"><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'">On</span></span><span class="codeintext-PRODUCTION"><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'; LETTER-SPACING: 0.2pt"> </span></span><span class="codeintext-PRODUCTION"><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'">Error</span></span><span class="codeintext-PRODUCTION"><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'; LETTER-SPACING: 0.2pt"> </span></span><span class="codeintext-PRODUCTION"><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'">Resume</span></span><span class="codeintext-PRODUCTION"><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'; LETTER-SPACING: 0.2pt"> </span></span><span class="codeintext-PRODUCTION"><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'">Next</span></span><span class="codeintext-PRODUCTION"><span style="FONT-FAMILY: 宋体">语句，通过</span></span><span class="codeintext-PRODUCTION"><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'">Err.Number</span></span><span class="codeintext-PRODUCTION"><span style="FONT-FAMILY: 宋体">检查调用每个组件，以确保该调用正常进行。</span></span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 16pt"><span class="importantwords-PRODUCTION"><span lang="EN-US" style="FONT-WEIGHT: normal; FONT-FAMILY: 'Times New Roman'">ASP.NET</span></span><span class="importantwords-PRODUCTION"><span style="FONT-WEIGHT: normal; FONT-FAMILY: 宋体">是</span></span><span class="importantwords-PRODUCTION"><span lang="EN-US" style="FONT-WEIGHT: normal; FONT-FAMILY: 'Times New Roman'">ASP</span></span><span class="importantwords-PRODUCTION"><span style="FONT-WEIGHT: normal; FONT-FAMILY: 宋体">的修订版本，它解决了</span></span><span class="importantwords-PRODUCTION"><span lang="EN-US" style="FONT-WEIGHT: normal; FONT-FAMILY: 'Times New Roman'">ASP</span></span><span class="importantwords-PRODUCTION"><span style="FONT-WEIGHT: normal; FONT-FAMILY: 宋体">的许多问题。但</span></span><span class="importantwords-PRODUCTION"><span lang="EN-US" style="FONT-WEIGHT: normal; FONT-FAMILY: 'Times New Roman'">ASP.NET</span></span><span class="importantwords-PRODUCTION"><span style="FONT-WEIGHT: normal; FONT-FAMILY: 宋体">页面并没有替代</span></span><span class="importantwords-PRODUCTION"><span lang="EN-US" style="FONT-WEIGHT: normal; FONT-FAMILY: 'Times New Roman'">ASP</span></span><span class="importantwords-PRODUCTION"><span style="FONT-WEIGHT: normal; FONT-FAMILY: 宋体">，而是可以与原来的</span></span><span class="importantwords-PRODUCTION"><span lang="EN-US" style="FONT-WEIGHT: normal; FONT-FAMILY: 'Times New Roman'">ASP</span></span><span class="importantwords-PRODUCTION"><span style="FONT-WEIGHT: normal; FONT-FAMILY: 宋体">应用程序在同一个服务器上同时并存。当然，也可以用</span></span><span class="importantwords-PRODUCTION"><span lang="EN-US" style="FONT-WEIGHT: normal; FONT-FAMILY: 'Times New Roman'">C#</span></span><span class="importantwords-PRODUCTION"><span style="FONT-WEIGHT: normal; FONT-FAMILY: 宋体">编写</span></span><span class="importantwords-PRODUCTION"><span lang="EN-US" style="FONT-WEIGHT: normal; FONT-FAMILY: 'Times New Roman'">ASP.NET</span></span><span class="importantwords-PRODUCTION"><span style="FONT-WEIGHT: normal; FONT-FAMILY: 宋体">。</span></span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 16pt"><span style="FONT-FAMILY: 宋体">后面的章节</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">第</span><span lang="EN-US">25-27</span><span style="FONT-FAMILY: 宋体">章</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">会详细讨论</span><span lang="EN-US">ASP.NET</span><span style="FONT-FAMILY: 宋体">，这里仅解释它的一些重要特性。</span></p>
<h4 style="TEXT-INDENT: 21.45pt"><span lang="EN-US">1. ASP.NET</span><span style="FONT-FAMILY: 黑体">的特性</span></h4>
<p class="MsoNormal" style="LINE-HEIGHT: 16pt"><span style="FONT-FAMILY: 宋体">首先，也是最重要的是，</span><span lang="EN-US">ASP.NET</span><span style="FONT-FAMILY: 宋体">页面是结构化的。这就是说，每个页面都是一个继承了</span><span lang="EN-US">.NET</span><span style="FONT-FAMILY: 宋体">类</span><span class="codeintext-PRODUCTION"><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'">System.Web.UI.Page</span></span><span class="codeintext-PRODUCTION"><span style="FONT-FAMILY: 宋体">的</span></span><span style="FONT-FAMILY: 宋体">类，可以重写在</span><span lang="EN-US">Page</span><span style="FONT-FAMILY: 宋体">对象的生存期中调用的一系列方法，</span><span lang="EN-US"> (</span><span style="FONT-FAMILY: 宋体">可以把这些事件看成是页面所特有的，对应于原</span><span lang="EN-US">ASP</span><span style="FONT-FAMILY: 宋体">的</span><span class="codeintext-PRODUCTION"><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'">global.asa</span></span><span class="codeintext-PRODUCTION"><span style="FONT-FAMILY: 宋体">文件中的</span></span><span class="codeintext-PRODUCTION"><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'">OnApplication_Start</span></span><span lang="EN-US"> </span><span style="FONT-FAMILY: 宋体">和</span><span class="codeintext-PRODUCTION"><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'">OnSession_Start</span></span><span class="codeintext-PRODUCTION"><span style="FONT-FAMILY: 宋体">事件</span></span><span class="codeintext-PRODUCTION"><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'">)</span></span><span class="codeintext-PRODUCTION"><span style="FONT-FAMILY: 宋体">。因为可以把一个页面的功能放在有明确含义的事件处理程序中，所以</span></span><span lang="EN-US">ASP.NET</span><span style="FONT-FAMILY: 宋体">比较容易理解。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 16pt"><span lang="EN-US">ASP.NET</span><span style="FONT-FAMILY: 宋体">页面的另一个优点是可以在</span><span lang="EN-US">VS.NET</span><span style="FONT-FAMILY: 宋体">中创建它们，在该环境下，可以创建</span><span lang="EN-US">ASP.NET</span><span style="FONT-FAMILY: 宋体">页面使用的业务逻辑和数据访问组件。</span><span lang="EN-US">VS.NET</span><span style="FONT-FAMILY: 宋体">项目组</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">也称为解决方案</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">包含了与应用程序相关的所有文件。而且，也可以在编辑器中调试传统的</span><span lang="EN-US">ASP</span><span style="FONT-FAMILY: 宋体">页面，在以前使用</span><span lang="EN-US">Visual InterDev</span><span style="FONT-FAMILY: 宋体">时，把</span><span lang="EN-US">InterDev</span><span style="FONT-FAMILY: 宋体">和项目的</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">服务器配置为支持调试常常是一个让人头痛的问题。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 16pt"><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -0.1pt">最清楚的是，</span><span lang="EN-US" style="LETTER-SPACING: -0.1pt">ASP.NET</span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -0.1pt">的后台编码功能允许进一步采用结构化的方式。</span><span lang="EN-US" style="LETTER-SPACING: -0.1pt">ASP.NET</span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -0.1pt">允许把页面的服务器端功能单独放在一个类中，把该类编译为</span><span lang="EN-US" style="LETTER-SPACING: -0.1pt">DLL</span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -0.1pt">，并把该</span><span lang="EN-US" style="LETTER-SPACING: -0.1pt">DLL</span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -0.1pt">放在</span><span lang="EN-US" style="LETTER-SPACING: -0.1pt">HTML</span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -0.1pt">部分下面的一个目录中。放在页面顶部的后台编码指令将把该文件与其</span><span lang="EN-US" style="LETTER-SPACING: -0.1pt">DLL</span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -0.1pt">关联起来。当浏览器请求该页面时，</span><span lang="EN-US" style="LETTER-SPACING: -0.1pt">Web</span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -0.1pt">服务器就会在页面的后台</span><span lang="EN-US" style="LETTER-SPACING: -0.1pt">DLL</span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -0.1pt">中引发类中的事件。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 16pt"><span lang="EN-US" style="LETTER-SPACING: -0.1pt">&nbsp;</span><span style="FONT-FAMILY: 宋体">最后</span><span lang="EN-US">ASP.NET</span><span style="FONT-FAMILY: 宋体">在性能的提高上非常明显。传统的</span><span lang="EN-US">ASP</span><span style="FONT-FAMILY: 宋体">页面是和每个页面请求一起进行解释，而</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">服务器是在编译后高速缓存</span><span lang="EN-US">ASP.NET</span><span style="FONT-FAMILY: 宋体">页面。这表示以后对</span><span lang="EN-US">ASP.NET</span><span style="FONT-FAMILY: 宋体">页面的请求就比</span><span lang="EN-US">ASP</span><span style="FONT-FAMILY: 宋体">页面的执行速度快得多。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 16pt"><span lang="EN-US">ASP.NET</span><span style="FONT-FAMILY: 宋体">还易于编写通过浏览器显示窗体的页面，这在内部网环境中会使用。传统的方式是基于窗体的应用程序提供一个功能丰富的用户界面，但较难维护，因为它们运行在非常多的不同机器上。因此，当用户界面是必不可少的，并可以为用户提供支持扩展时，人们就会依赖于基于窗体的应用程序。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 16pt"><span style="FONT-FAMILY: 宋体">但随着</span><span lang="EN-US">Internet Explorer 5</span><span style="FONT-FAMILY: 宋体">的出现，而</span><span lang="EN-US">Navigator 6</span><span style="FONT-FAMILY: 宋体">的性能乏善可陈时，基于窗体的应用程序的优点就非常突出了。</span><span lang="EN-US">IE 5</span><span style="FONT-FAMILY: 宋体">对</span><span lang="EN-US">DHTML</span><span style="FONT-FAMILY: 宋体">的健全的支持，允许程序员创建基于</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">的应用程序，这些应用程序都能很好地对应于其客户端程序。当然，这种应用程序需要在</span><span lang="EN-US">IE</span><span style="FONT-FAMILY: 宋体">上进行标准化，而不支持</span><span lang="EN-US">Navigator</span><span style="FONT-FAMILY: 宋体">。在许多行业中，这种标准化现在是很常见的。</span></p>
<h4 style="TEXT-INDENT: 21.45pt"><span lang="EN-US">2. Web</span><span style="FONT-FAMILY: 黑体">窗体</span></h4>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">页面的结构，</span><span lang="EN-US">Visual Studio .NET</span><span style="FONT-FAMILY: 宋体">提供了</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">窗体。它们允许以创建</span><span lang="EN-US">VB6</span><span style="FONT-FAMILY: 宋体">或</span><span lang="EN-US"> C++ Builder</span><span style="FONT-FAMILY: 宋体">窗口的方式图形化地建立</span><span lang="EN-US">ASP.NET</span><span style="FONT-FAMILY: 宋体">页面；换言之，就是把控件从工具箱拖放到窗体上，再考虑窗体的代码，为控件编写事件处理程序。在使用</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">创建</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">窗体时，就是创建一个继承于</span><span class="codeintext-PRODUCTION"><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'">Page</span></span><span lang="EN-US"> </span><span style="FONT-FAMILY: 宋体">基类的</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">类，以及把这个类看做是后台编码的</span><span lang="EN-US">ASP.NET</span><span style="FONT-FAMILY: 宋体">页面。当然不必使用</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">创建</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">窗体，而可以使用</span><span lang="EN-US">VB.NET</span><span style="FONT-FAMILY: 宋体">或另一种</span><span lang="EN-US">.NET</span><span style="FONT-FAMILY: 宋体">语言来创建。</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">过去，</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">开发的困难使一些开发小组不愿意使用</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">。为了成功地进行</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">开发，必须了解非常多的不同技术，例如</span><span lang="EN-US">VBScript</span><span style="FONT-FAMILY: 宋体">、</span><span lang="EN-US">ASP</span><span style="FONT-FAMILY: 宋体">、</span><span lang="EN-US">DHTML</span><span style="FONT-FAMILY: 宋体">、</span><span lang="EN-US">JavaScript</span><span style="FONT-FAMILY: 宋体">等。把窗体概念应用于</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">页面，</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">窗体就可以使</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">开发容易许多。</span></p>
<p class="a3" style="MARGIN-TOP: 8.15pt; TEXT-INDENT: 21.45pt"><span lang="EN-US">Web</span><span style="FONT-FAMILY: 黑体">控件</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">窗体上的控件与</span><span lang="EN-US">ActiveX</span><span style="FONT-FAMILY: 宋体">控件并不是同一种控件，它们是</span><span lang="EN-US">ASP.NET</span><span style="FONT-FAMILY: 宋体">命名空间中的</span><span lang="EN-US">XML</span><span style="FONT-FAMILY: 宋体">标记，当请求一个页面时，</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">浏览器会动态地把它们转换为</span><span lang="EN-US">HTML</span><span style="FONT-FAMILY: 宋体">和客户端脚本。</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">服务器能以不同的方式显示相同的服务器端控件，产生一个对应于请求者特定</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">浏览器的转换。这意味着现在很容易为</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">页面编写相当复杂的用户界面，而不必担心如何确保页面运行在可用的任何浏览器上，因为</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">窗体会完成这些任务。</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">可以使用</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">或</span><span lang="EN-US">VB.NET</span><span style="FONT-FAMILY: 宋体">扩展</span><span lang="EN-US">Web</span><span style="FONT-FAMILY: 宋体">窗体工具箱。创建一个新服务器端控件，仅是执行</span><span lang="EN-US">.NET</span><span style="FONT-FAMILY: 宋体">的</span><span class="codeintext-PRODUCTION"><span lang="EN-US" style="FONT-FAMILY: 'Times New Roman'">System.Web.UI.WebControls.WebControl</span></span><span style="FONT-FAMILY: 宋体">类而已。</span></p>
<h4 style="TEXT-INDENT: 21.45pt"><span lang="EN-US">3. XML Web</span><span style="FONT-FAMILY: 黑体">服务</span></h4>