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来自「C#高级编程(第三版),顶死你们。。 。up」· HTM 代码 · 共 268 行 · 第 1/2 页

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>using
Wrox.ProCSharp.COMInterop.Server;</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>namespace
Wrox.ProCSharp.COMInterop.Client</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>&nbsp;
class Class1</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;
{</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;
[STAThread]</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;
static void Main(string[] args)</span></p>

<p class=2 style='margin-top:0cm;margin-right:0cm;FTEL:8.15pt;
margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp; {</span></p>

<p class=MsoNormal><span style='font-family:宋体'>现在可以像使用</span><span lang=EN-US>.NET</span><span
style='font-family:宋体'>类那样使用</span><span lang=EN-US>COM</span><span
style='font-family:宋体'>组件了。</span><span lang=EN-US>obj</span><span
style='font-family:宋体'>是</span><span lang=EN-US>COMDemo</span><span
style='font-family:宋体'>类型的变量，</span><span lang=EN-US>COMDemo</span><span
style='font-family:宋体'>是一个</span><span lang=EN-US>.NET</span><span
style='font-family:宋体'>接口，它提供了</span><span lang=EN-US>IWelcome</span><span
style='font-family:宋体'>和</span><span lang=EN-US>IMath</span><span
style='font-family:宋体'>接口的方法。还可以对特定的接口进行强制数据类型转换，例如</span><span lang=EN-US>IWelcome</span><span
style='font-family:宋体'>。有了声明为</span><span lang=EN-US>IWelcome</span><span
style='font-family:宋体'>类型的变量后，就可以调用方法</span><span lang=EN-US>Greeting()</span><span
style='font-family:宋体'>。</span></p>

<p class=2 style='margin-top:8.15pt;margin-right:0cm;FTEL:0cm;
margin-left:21.45pt;FTEL:.0001pt;FTEL:18.45pt'><span
lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; COMDemo obj = new
COMDemoClass();</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
IWelcome welcome = (IWelcome)obj;</span></p>

<p class=2 style='margin-top:0cm;margin-right:0cm;FTEL:8.15pt;
margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Console.WriteLine(obj.Greeting(&quot;Christian&quot;));</span></p>

<p class=MsoNormal><span style='font-family:宋体'>如果对象</span><span lang=EN-US>(</span><span
style='font-family:宋体'>如本例所示</span><span lang=EN-US>)</span><span
style='font-family:宋体'>提供了多个接口，就可以声明其他接口的变量，通过使用简单的赋值语句和强制转换运算符，包装器类就有一个</span><span
lang=EN-US>QueryInterface()</span><span style='font-family:宋体'>方法和返回第二个接口指针的</span><span
lang=EN-US>COM</span><span style='font-family:宋体'>对象。使用</span><span lang=EN-US>math</span><span
style='font-family:宋体'>变量可以调用</span><span lang=EN-US>IMath</span><span
style='font-family:宋体'>接口的方法。</span></p>

<p class=2 style='margin-top:8.15pt;margin-right:0cm;FTEL:0cm;
margin-left:21.45pt;FTEL:.0001pt;FTEL:18.45pt'><span
lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; IMath math;</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;math = (IMath)obj;</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
int x = math.Add(4,5);</span></p>

<p class=2 style='margin-top:0cm;margin-right:0cm;FTEL:8.15pt;
margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Console.WriteLine(x);</span></p>

<p class=MsoNormal><span style='font-family:宋体'>如果在垃圾收集器清理对象之前释放</span><span
lang=EN-US>COM</span><span style='font-family:宋体'>对象，静态方法</span><span
lang=EN-US>Marshal.ReleaseComObject()</span><span style='font-family:宋体'>就调用组件的</span><span
lang=EN-US>Release()</span><span style='font-family:宋体'>方法，这样组件就可以销毁它自己，并释放内存了。</span></p>

<p class=2 style='margin-top:8.15pt;margin-right:0cm;FTEL:0cm;
margin-left:21.45pt;FTEL:.0001pt;FTEL:18.45pt'><span
lang=EN-US>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Marshal.ReleaseComObject(math);</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;&nbsp;&nbsp;
}</span></p>

<p class=2 style='margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>&nbsp;
}</span></p>

<p class=2 style='margin-top:0cm;margin-right:0cm;FTEL:8.15pt;
margin-left:21.45pt;FTEL:18.45pt'><span lang=EN-US>}</span></p>

<p class=MsoNormal><span style='font-family:宋体'>可以看出，有了</span><span lang=EN-US>RCW</span><span
style='font-family:宋体'>，就可以像使用</span><span lang=EN-US>.NET</span><span
style='font-family:宋体'>对象那样来使用</span><span lang=EN-US>COM</span><span
style='font-family:宋体'>组件。</span></p>

<p class=MsoNormal><span lang=EN-US>RCW</span><span style='font-family:宋体'>的特殊情况是可交互操作的主程序集。</span></p>

<h4 style='FTEL:21.45pt'><span lang=EN-US>1. </span><span
style='font-family:黑体'>可交互操作的主程序集</span></h4>

<p class=MsoNormal><span style='font-family:宋体'>可交互操作的主程序集是</span><span
lang=EN-US>COM</span><span style='font-family:宋体'>组件的供应商已经准备好的程序集。它可以更容易地使用</span><span
lang=EN-US>COM</span><span style='font-family:宋体'>对象。可交互操作的主程序集不同于自动生成的</span><span
lang=EN-US>RCW</span><span style='font-family:宋体'>。</span></p>

<p class=MsoNormal><span style='font-family:宋体'>可交互操作的主程序集在目录</span><span
lang=EN-US>&lt;program file&gt;\Microsoft .NET\Primary Interop Assemblies</span><span
style='font-family:宋体'>中。它已经存在，用于</span><span lang=EN-US>.NET</span><span
style='font-family:宋体'>中的</span><span lang=EN-US>ADO</span><span
style='font-family:宋体'>。如果添加对</span><span lang=EN-US>COM</span><span
style='font-family:宋体'>库</span><span lang=EN-US>Microsoft ActiveX Data Objects
2.7 Library</span><span style='font-family:宋体'>的引用，就不创建包装器类，因为可交互操作的主程序集已经存在；否则就引用可交互操作的主程序集。</span></p>

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