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<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> foreach (Attribute nextAttrib in attribs2)</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> WriteAttributeInfo(nextAttrib);</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="2" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 15pt"><span style="FONT-FAMILY: 宋体">注意，在这个方法中，首先应检查参数</span><span lang="EN-US">Type</span><span style="FONT-FAMILY: 宋体">引用是否表示一个类。为了简化代码，指定</span><span lang="EN-US">LastModified</span><span style="FONT-FAMILY: 宋体">特性只能应用于类或成员方法，如果该引用不是类</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">它可能是一个结构、委托或枚举</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">，进行任何处理都是浪费时间。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 15pt"><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -0.2pt">接着使用</span><span lang="EN-US" style="LETTER-SPACING: -0.2pt">Attribute.GetCustomAttributes()</span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -0.2pt">方法查找这个类是否有相关的</span><span lang="EN-US" style="LETTER-SPACING: -0.2pt">LastModifiedAttribute</span><span style="FONT-FAMILY: 宋体">实例。如果有，就使用帮助方法</span><span lang="EN-US">WriteAttributeInfo()</span><span style="FONT-FAMILY: 宋体">把它们的信息添加到输出文本中。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 15pt"><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -0.1pt">最后使用</span><span lang="EN-US" style="LETTER-SPACING: -0.1pt">Type.GetMethods()</span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -0.1pt">方法迭代这个数据类型的所有成员方法，然后对类的每个方法进行相同的处理：检查每个方法是否有相关的</span><span lang="EN-US" style="LETTER-SPACING: -0.1pt">LastModifiedAttribute</span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -0.1pt">实例，如果有，用</span><span lang="EN-US" style="LETTER-SPACING: -0.1pt">WriteAttribute Info()</span><span style="FONT-FAMILY: 宋体">显示方法它们。</span></p>
<p class="MsoNormal" style="LINE-HEIGHT: 15pt"><span style="FONT-FAMILY: 宋体">下面的代码显示了</span><span lang="EN-US">WriteAttributeInfo()</span><span style="FONT-FAMILY: 宋体">方法，它负责确定为给定的</span><span lang="EN-US">LastModifiedAttribute</span><span style="FONT-FAMILY: 宋体">实例显示什么文本，注意这个方法的参数是一个</span><span lang="EN-US">Attribute</span><span style="FONT-FAMILY: 宋体">引用，所以需要先把该引用转换为</span><span lang="EN-US">LastModifiedAttribute</span><span style="FONT-FAMILY: 宋体">引用。之后，就可以使用最初为这个特性定义的属性获取其参数。在把该特性添加到要显示的文本中之前，应检查特性的日期是否是最近的：</span></p>
<p class="2" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US"> static void WriteAttributeInfo(Attribute attrib)</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> LastModifiedAttribute lastModifiedAttrib =</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> attrib as LastModifiedAttribute;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> if (lastModifiedAttrib == null)</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> return;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> // check that date is in range</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> DateTime modifiedDate = lastModifiedAttrib.DateModified;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> if (modifiedDate < backDateTo)</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> return;</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> AddToMessage(" MODIFIED: " +</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> modifiedDate.ToLongDateString() + ":");</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> AddToMessage(" " + lastModifiedAttrib.Changes);</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> if (lastModifiedAttrib.Issues != null)</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; LINE-HEIGHT: 13pt; FTEL: 18.45pt"><span lang="EN-US"> AddToMessage(" Outstanding issues:" + lastModifiedAttrib.Issues);</span></p>
<p class="2" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">最后，是辅助方法</span><span lang="EN-US">AddToMessage()</span><span style="FONT-FAMILY: 宋体">：</span></p>
<p class="2" style="MARGIN-TOP: 8.15pt; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US"> static void AddToMessage(string message)</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"> outputText.Append("\n" + message);</span></p>
<p class="2" style="MARGIN-TOP: 0cm; MARGIN-LEFT: 21.45pt; MARGIN-RIGHT: 0cm; FTEL: 18.45pt"><span lang="EN-US"> }</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">运行这段代码，得到如图</span><span lang="EN-US">10-2</span><span style="FONT-FAMILY: 宋体">所示的结果。</span></p>
<p align="center"><span lang="EN-US"><img height="422" src="10/image002.jpg" width="320" alt="" /></span></p>
<p style="FTEL: 8.15pt" align="center"><span style="FONT-FAMILY: 宋体">图</span><span lang="EN-US"> 10-2</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">注意，在列出</span><span lang="EN-US">VectorClass</span><span style="FONT-FAMILY: 宋体">程序集中定义的类型时，<span style="LETTER-SPACING: -0.1pt">实际上选择了两个类：</span></span><span lang="EN-US" style="LETTER-SPACING: -0.1pt">Vector</span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -0.1pt">和内嵌的</span><span lang="EN-US" style="LETTER-SPACING: -0.1pt">VectorEnumerator</span><span style="FONT-FAMILY: 宋体; LETTER-SPACING: -0.1pt">类。</span><span style="FONT-FAMILY: 宋体">还要注意，这段代码把</span><span lang="EN-US">backDateTo</span><span style="FONT-FAMILY: 宋体">日期硬编码为</span><span lang="EN-US">2</span><span style="FONT-FAMILY: 宋体">月</span><span lang="EN-US">1</span><span style="FONT-FAMILY: 宋体">日，实际上选择的是日期为</span><span lang="EN-US">2</span><span style="FONT-FAMILY: 宋体">月</span><span lang="EN-US">14</span><span style="FONT-FAMILY: 宋体">日的特性</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">添加集合成员的时间</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">，而不是</span><span lang="EN-US">1</span><span style="FONT-FAMILY: 宋体">月</span><span lang="EN-US">14</span><span style="FONT-FAMILY: 宋体">日</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">添加</span><span lang="EN-US">IFormattable</span><span style="FONT-FAMILY: 宋体">接口的时间</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">。</span></p></div>
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<h1 id="divCurrentNode2" style="color: #b83507; width: 100%; text-align: left; font-size: 12px; padding-left: 2px">当前章节:<a href='100165371.htm'><font color='red'>10.2.4 完成WhatsNewAttributes示例</font></a></h1>
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<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 style='float:left;width:49%'>·<a href='100165370.htm'>10.2.3 Assembly类</a></div><div style='float:right;width:49%'>·<a href='100165372.htm'>10.3 小结</a></div><div style='float:left;width:49%'>·<a href='100165419.htm'>14.1 代码访问的安全性</a></div><div style='float:right;width:49%'>·<a href='100165420.htm'>14.1.1 代码组</a></div></div>
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