100165366.htm
来自「C#高级编程(第三版),顶死你们。。 。up」· HTM 代码 · 共 172 行 · 第 1/2 页
HTM
172 行
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head><title>
10.1.2 定制特性示例WhatsNewAttributes
</title></head>
<body>
<div class="area">
<div class="col1">
<div class="lineBlue">
</div>
<!-- title -->
<div class="arcTitle">
<h1>
<a href="../16">
C#高级编程（第3版）【全文连载】
</a>
</h1>
<div style="text-align: center; font-size: 15px">
<a href="100165366.htm">
10.1.2 定制特性示例WhatsNewAttributes
</a>
</div>
<div style="text-align: center; font-size: 15px">
<a class="url" href="../../default.htm">http://book.csdn.net/</a>
2006-10-13 14:41:00
</div>
<div style="margin: 0px auto; width: 700px; border: solid 1px #0b5f98;">
<div style="float: left; width: 16px; background-color: #0b5f98; color: White; padding: 1px;">
图书导读
</div>
<div style="float: right; width: 670px; text-align: left; line-height: 16pt; padding-left: 2px">
<!--导读-->
<h1 id="divCurrentNode" style="color: #b83507; width: 100%; text-align: left; font-size: 12px; padding-left: 2px">当前章节:<a href='100165366.htm'><font color='red'>10.1.2 定制特性示例WhatsNewAttributes</font></a></h1>
<div id="divRelateNode" style="padding-left: 2px">
<div style='float:left;width:49%'>·<a href='100165363.htm'>9.2 小结</a></div><div style='float:right;width:49%'>·<a href='100165364.htm'>10.1 定制特性</a></div><div style='float:left;width:49%'>·<a href='100165365.htm'>10.1.1 编写定制特性</a></div><div style='float:right;width:49%'>·<a href='100165367.htm'>10.2 反射</a></div><div style='float:left;width:49%'>·<a href='100165368.htm'>10.2.1 System.Type类</a></div><div style='float:right;width:49%'>·<a href='100165369.htm'>10.2.2 TypeView示例</a></div></div>
</div>
</div>
</div>
<!-- main -->
<div id="main">
<div id="text"> <link href="css.css" rel="stylesheet" type="text/css" /><h3 style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 0cm; MARGIN-RIGHT: 0cm; FTEL: 8.15pt"><a ftel="_Toc507815078"><span lang="EN-US">10.1.2 </span></a><span style="FONT-FAMILY: 黑体">定制特性示例</span><span lang="EN-US">WhatsNewAttributes</span><span lang="EN-US"> </span></h3>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">本节开始编写前面描述过的示例</span><span lang="EN-US">WhatsNewAttributes</span><span style="FONT-FAMILY: 宋体">，该示例提供了一个特性，表示最后一次修改的程序元素。这个示例比前面所有的示例都复杂，因为它包含</span><span lang="EN-US">3</span><span style="FONT-FAMILY: 宋体">个不同的程序集：</span></p>
<p class="1" style="MARGIN-LEFT: 37.55pt; FTEL: -16.1pt"><span lang="EN-US">●<span style="FONT: 7pt 'Times New Roman'"> </span></span><span lang="EN-US">WhatsNewAttributes</span><span style="FONT-FAMILY: 宋体">程序集，它包含特性的定义。</span></p>
<p class="1" style="MARGIN-LEFT: 37.55pt; FTEL: -16.1pt"><span lang="EN-US">●<span style="FONT: 7pt 'Times New Roman'"> </span></span><span lang="EN-US">VectorStruct</span><span style="FONT-FAMILY: 宋体">程序集，包含所应用的特性的代码</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">这类似于前几章使用的</span><span lang="EN-US">Vector</span><span style="FONT-FAMILY: 宋体">示例</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">。</span></p>
<p class="1" style="MARGIN-LEFT: 37.55pt; FTEL: -16.1pt"><span lang="EN-US">●<span style="FONT: 7pt 'Times New Roman'"> </span></span><span lang="EN-US">LookUpWhatsNew</span><span style="FONT-FAMILY: 宋体">程序集包含显示已改变的数据项信息的项目。</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">到目前为止，其中只有</span><span lang="EN-US">LookUpWhatsNew</span><span style="FONT-FAMILY: 宋体">是所使用的一个控制台应用程序，其余两个程序集都是库文件，它们都包含类的定义，但都没有程序的入口。对于</span><span lang="EN-US">VectorStruct</span><span style="FONT-FAMILY: 宋体">程序集，我们是使用了</span><span lang="EN-US">VectorAsCollection</span><span style="FONT-FAMILY: 宋体">示例，但删除了入口和测试代码类，只剩下</span><span lang="EN-US">Vector</span><span style="FONT-FAMILY: 宋体">类。</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">在命令行上编译，以此管理</span><span lang="EN-US">3</span><span style="FONT-FAMILY: 宋体">个相关的程序集要求较高的技巧，所以我们分别给出编译这</span><span lang="EN-US">3</span><span style="FONT-FAMILY: 宋体">个源文件的命令。您也可以编辑代码示例，</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">可以从</span><span lang="EN-US">Wrox Press</span><span style="FONT-FAMILY: 宋体">网站上下载</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">，组合为一个</span><span lang="EN-US">Visual Studio .NET</span><span style="FONT-FAMILY: 宋体">解决方案，详见第</span><span lang="EN-US">12</span><span style="FONT-FAMILY: 宋体">章。下载的文件包含所需的</span><span lang="EN-US">Visual Studio .NET</span><span style="FONT-FAMILY: 宋体">解决方案文件。</span></p>
<h4 style="FTEL: 21.45pt"><span lang="EN-US">1. WhatsNewAttributes </span><span style="FONT-FAMILY: 黑体">库程序集</span></h4>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">首先从核心的</span><span lang="EN-US">WhatsNewAttributes</span><span style="FONT-FAMILY: 宋体">程序集开始。其源代码包含在文件</span><span lang="EN-US">WhatsNew Attributes.cs</span><span style="FONT-FAMILY: 宋体">中，编译为库的语法非常简单：在命令行上，给编译器提供标记</span><span lang="EN-US">target:library</span><span style="FONT-FAMILY: 宋体">即可。要编译</span><span lang="EN-US">WhatsNewAttributes</span><span style="FONT-FAMILY: 宋体">，键入：</span></p>
<p class="a6" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><strong><span lang="EN-US">csc /target:library WhatsNewAttributes.cs</span></strong></p>
<p class="MsoNormal"><span lang="EN-US">WhatsNewAttributes.cs</span><span style="FONT-FAMILY: 宋体">文件定义了两个特性类</span><span lang="EN-US">LastModifiedAttribute</span><span style="FONT-FAMILY: 宋体">和</span><span lang="EN-US">SupportsWhatsNew Attribute</span><span style="FONT-FAMILY: 宋体">。</span><span lang="EN-US">LastModifiedAttribute</span><span style="FONT-FAMILY: 宋体">特性可以用于标记最后一次修改数据项的时间，它有两个必选参数</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">该参数传递给构造函数</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">；修改的日期和包含描述修改的字符串。它还有一个可选参数</span><span lang="EN-US">Issues (</span><span style="FONT-FAMILY: 宋体">表示存在一个公共属性</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">，它可以描述该数据项的任何重要问题。</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">在现实生活中，或许想把特性应用到任何对象上。为了使代码比较简单，这里仅允许将它应用于类和方法，并允许它多次应用到同一个项目上</span><span lang="EN-US">(AllowMultiple=true)</span><span style="FONT-FAMILY: 宋体">，因为可以多次修改一个项目，每次修改都需要用一个不同的特性实例来标记。</span></p>
<p class="MsoNormal"><span lang="EN-US">SupportsWhatsNew</span><span style="FONT-FAMILY: 宋体">是一个较小的类，表示不带任何参数的特性。这个特性是一个程序集的特性，用于把程序集标记为通过</span><span lang="EN-US">LastModifiedAttribute</span><span style="FONT-FAMILY: 宋体">维护的文档说明书。这样，以后查看这个程序集的程序会知道，它读取的程序集是我们所使用的自动文档说明过程上的那个程序集。这部分示例的完整源代码如下所示：</span></p>
<p class="2" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">using System;</span></p>
<p class="2" style="MARGIN-TOP: 6pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US">namespace Wrox.ProCSharp.WhatsNewAttributes</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US">{</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> [AttributeUsage(</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> AttributeTargets.Class | AttributeTargets.Method,</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> AllowMultiple=true, Inherited=false)]</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> public class LastModifiedAttribute : Attribute</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> private DateTime dateModified;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> private string changes;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> private string issues;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> public LastModifiedAttribute(string dateModified, string changes)</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> this.dateModified = DateTime.Parse(dateModified);</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> this.changes = changes;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> public DateTime DateModified</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> get</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> return dateModified;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; FTEL: 18.45pt"><span lang="EN-US"> public string Changes</span></p>
⌨️ 快捷键说明
复制代码Ctrl + C
搜索代码Ctrl + F
全屏模式F11
增大字号Ctrl + =
减小字号Ctrl + -
显示快捷键?