100165819.htm
来自「C#高级编程(第三版),顶死你们。。 。up」· HTM 代码 · 共 264 行 · 第 1/4 页
HTM
264 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>
4.4 接口
</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="100165819.htm">
4.4 接口
</a>
</div>
<div style="text-align: center; font-size: 15px">
<a class="url" href="../../default.htm">http://book.csdn.net/</a>
2006-10-13 14:50:00
</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='100165819.htm'><font color='red'>4.4 接口</font></a></h1>
<div id="divRelateNode" style="padding-left: 2px">
<div style='float:left;width:49%'>·<a href='100165816.htm'>4.1 继承的类型</a></div><div style='float:right;width:49%'>·<a href='100165817.htm'>4.2 实现的继承</a></div><div style='float:left;width:49%'>·<a href='100165818.htm'>4.3 修饰符</a></div><div style='float:right;width:49%'>·<a href='100165826.htm'>4.5 小结</a></div></div>
</div>
</div>
</div>
<!-- main -->
<div id="main">
<div id="text"> <link href="css.css" rel="stylesheet" type="text/css" /><p class="MsoNormal"><span></span><span lang="EN-US" style="BACKGROUND: aqua"><span></span></span><span style="FONT-FAMILY: 宋体">如前所述，如果一个类派生于一个接口，它就会执行某些函数。并不是所有的面向对象语言都支持接口，所以本节将详细介绍</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">接口的实现。</span></p>
<p class="a3" style="MARGIN-TOP: 8.15pt; TEXT-INDENT: 21.45pt"><span style="FONT-FAMILY: 黑体">注意：</span></p>
<p class="a1" style="MARGIN-BOTTOM: 8.15pt; TEXT-INDENT: 21.45pt"><span style="FONT-FAMILY: 楷体_GB2312">熟悉</span><span lang="EN-US">COM</span><span style="FONT-FAMILY: 楷体_GB2312">的开发人员应注意，尽管在概念上</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 楷体_GB2312">接口类似于</span><span lang="EN-US">COM</span><span style="FONT-FAMILY: 楷体_GB2312">接口，但它们是不同的，底层的结构不同，例如，</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 楷体_GB2312">接口并不派生于</span><span lang="EN-US">IUnknown</span><span style="FONT-FAMILY: 楷体_GB2312">。</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 楷体_GB2312">接口根据</span><span lang="EN-US">.NET</span><span style="FONT-FAMILY: 楷体_GB2312">函数提供了一个契约。与</span><span lang="EN-US">COM</span><span style="FONT-FAMILY: 楷体_GB2312">接口不同，</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 楷体_GB2312">接口不代表任何类型的二进制标准。</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">下面列出</span><span lang="EN-US">Microsoft</span><span style="FONT-FAMILY: 宋体">预定义的一个接口的完整定义，</span><span lang="EN-US">System.IDisposable</span><span style="FONT-FAMILY: 宋体">。</span><span lang="EN-US">IDisposable</span><span style="FONT-FAMILY: 宋体">包含一个方法</span><span lang="EN-US">Dispose()</span><span style="FONT-FAMILY: 宋体">，该方法由类执行，用于清理代码：</span></p>
<p class="2" style="MARGIN: 8.15pt 0cm 0pt 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">public interface IDisposable </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">{</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> void Dispose();</span></p>
<p class="2" style="MARGIN: 0cm 0cm 8.15pt 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">}</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">上面的代码说明，声明接口在语法上与声明抽象类完全相同，但不允许提供接口中任何成员的执行方式。一般情况下，接口中只能包含方法、属性、索引器和事件的声明。</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">不能实例化接口，它只能包含其成员的签名。接口不能有构造函数</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">如何构建不能实例化的对象？</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">或字段</span><span lang="EN-US">(</span><span style="FONT-FAMILY: 宋体">因为这隐含了某些内部的执行方式</span><span lang="EN-US">)</span><span style="FONT-FAMILY: 宋体">。接口定义也不允许包含运算符重载，但这不是因为声明它们在原则上有什么问题，而是因为接口通常是公共契约，包含运算符重载会引起一些与其他</span><span lang="EN-US">.NET</span><span style="FONT-FAMILY: 宋体">语言不兼容的问题，例如与</span><span lang="EN-US">VB.NET</span><span style="FONT-FAMILY: 宋体">的不兼容，因为</span><span lang="EN-US">VB.NET</span><span style="FONT-FAMILY: 宋体">不支持运算符重载。</span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">在接口定义中还不允许声明成员上的修饰符。接口成员总是公共的，不能声明为虚拟或静<span style="LETTER-SPACING: 0.1pt">态。如果需要，就应由执行的类来声明，因此最好通过执行的类来声明访问修饰符，就像上面的代码那样。</span></span></p>
<p class="MsoNormal"><span style="FONT-FAMILY: 宋体">例如</span><span lang="EN-US">IDisposable</span><span style="FONT-FAMILY: 宋体">。如果类希望声明为公共类型，以便执行方法</span><span lang="EN-US">Dispose()</span><span style="FONT-FAMILY: 宋体">，该类就必须执行</span><span lang="EN-US">IDisposable</span><span style="FONT-FAMILY: 宋体">。在</span><span lang="EN-US">C#</span><span style="FONT-FAMILY: 宋体">中，这表示该类派生于</span><span lang="EN-US">IDisposable</span><span style="FONT-FAMILY: 宋体">。</span></p>
<p class="2" style="MARGIN: 8.15pt 0cm 0pt 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">class SomeClass : IDisposable</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US">{</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> // this class MUST contain an implementation of the </span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> // IDisposable.Dispose() method, otherwise</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> // you get a compilation error</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> public void Dispose()</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> {</span></p>
<p class="2" style="MARGIN-LEFT: 21.45pt; TEXT-INDENT: 18.45pt"><span lang="EN-US"> // implementation of Dispose() method</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?