详细介绍有关于.NET的委托
发布时间：2020-07-16 04:19:50 所属栏目：asp.Net 来源：互联网
导读：.NET学习中，你碰到过委托吗？我接触.NET几个月以来，关于委托的确花了我好长时间才弄明白，这里我就C#中的委托给大家介绍一下。（先说定义和特征，然后用例子说明） 委托是回调函数的类型安全包装。C++编写的非托管程序进行回调时很容易出错。由于委托的存
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<span style="FONT-SIZE: 10pt"> .NET学习中，你碰到过委托吗？我接触.NET几个月以来，关于委托的确花了我好长时间才弄明白，这里我就C#中的委托给大家介绍一下。（先说定义和特征，然后用例子说明） <p style="FONT-SIZE: 10pt"> C#中的委托类似于C或C++中的函数指针。使用委托使程序员可以将方法引用封装在委托对象内（ 所以这里的“引用”不是原始内存地址，而是包装了方法的内存地址的委托实例 ）。然后可以将给委托对象传递可调用所引用方法的代码，而不必在编译时知道将调用哪个方法。与C或C++中的函数指针不同，委托是面向对象、类型安全的，并且是安全的。 <p style="FONT-SIZE: 10pt"> 委托声明定义一种类型，它用一组特定的参数以及返回类型封装方法。 <p style="FONT-SIZE: 10pt"> 对于静态方法，委托对象封装要调用的方法。 <p style="FONT-SIZE: 10pt"> 对于实例方法，委托对象同时封装一个实例和该实例上的一个方法。 <p style="FONT-SIZE: 10pt"> 如果你有一个委托对象和一组适当的参数，则可以用这些参数调用该委托。 <p style="FONT-SIZE: 10pt"> 委托的一个有趣且有用的属性是： 它不知道或不关心自己引用的对象的类。任何对象都可以，知识方法的参数类型必须与委托的参数类型和返回类型相匹配。这是的委托完全适合“匿名”调用。 <p style="FONT-SIZE: 10pt"> 到现在已经说得不少了，现在开始用例子说明如何声明、实例化和调用委托：下面的示例中，BookDB 类封装一个书店数据库，它维护一个书籍数据库。它公开 ProcessPaperbackBooks 方法，该方法在数据库中查找所有平装书，并为每本书调用一个委托。所使用的 delegate 类型称为 ProcessBookDelegate.Test 类使用该类输出平装书的书名和平均价格。委托的使用促进了书店数据库和客户代码之间功能的良好分隔。客户代码不知道书籍的存储方式和书店代码查找平装书的方式。书店代码也不知道找到平装书后将对平装书进行什么处理。 <div style="FONT-SIZE: 10pt"> <div style="FONT-SIZE: 10pt"> <img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">//bookstore.cs<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">usingSystem;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">//此命名空间中的几个类用以维护书籍数据库:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">namespaceBookstore<img id="_75_1230_Open_Image" onclick="this.style.display='none'; document.getElementById('_75_1230_Open_Text').style.display='none'; document.getElementById('_75_1230_Closed_Image').style.display='inline'; document.getElementById('_75_1230_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954295.gif" align="top"><img id="_75_1230_Closed_Image" onclick="this.style.display='none'; document.getElementById('_75_1230_Closed_Text').style.display='none'; document.getElementById('_75_1230_Open_Image').style.display='inline'; document.getElementById('_75_1230_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954584.gif" align="top">...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">usingSystem.Collections;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">//描述数据库中每一本书具有的属性:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">publicstructBook<img id="_155_535_Open_Image" onclick="this.style.display='none'; document.getElementById('_155_535_Open_Text').style.display='none'; document.getElementById('_155_535_Closed_Image').style.display='inline'; document.getElementById('_155_535_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_155_535_Closed_Image" onclick="this.style.display='none'; document.getElementById('_155_535_Closed_Text').style.display='none'; document.getElementById('_155_535_Open_Image').style.display='inline'; document.getElementById('_155_535_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">publicstringTitle;//书的题目.<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">publicstringAuthor;//书的作者.<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">publicdecimalPrice;//书的价格.<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">publicboolPaperback;//是不是平装书?<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">publicBook(stringtitle,stringauthor,decimalprice,boolpaperBack)<img id="_416_530_Open_Image" onclick="this.style.display='none'; document.getElementById('_416_530_Open_Text').style.display='none'; document.getElementById('_416_530_Closed_Image').style.display='inline'; document.getElementById('_416_530_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_416_530_Closed_Image" onclick="this.style.display='none'; document.getElementById('_416_530_Closed_Text').style.display='none'; document.getElementById('_416_530_Open_Image').style.display='inline'; document.getElementById('_416_530_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">Title=title;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">Author=author;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">Price=price;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">Paperback=paperBack;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">//为处理平装书的类声明一个委托类型（delegate类型）:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">publicdelegatevoidProcessBookDelegate(Bookbook);<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">//维护书籍的数据库.<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">publicclassBookDB<img id="_673_1228_Open_Image" onclick="this.style.display='none'; document.getElementById('_673_1228_Open_Text').style.display='none'; document.getElementById('_673_1228_Closed_Image').style.display='inline'; document.getElementById('_673_1228_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_673_1228_Closed_Image" onclick="this.style.display='none'; document.getElementById('_673_1228_Closed_Text').style.display='none'; document.getElementById('_673_1228_Open_Image').style.display='inline'; document.getElementById('_673_1228_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">//数据库中所有书籍的清单:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">ArrayListlist=newArrayList();<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">//向数据库中添加一本书:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">publicvoidAddBook(stringtitle,boolpaperBack)<img id="_854_924_Open_Image" onclick="this.style.display='none'; document.getElementById('_854_924_Open_Text').style.display='none'; document.getElementById('_854_924_Closed_Image').style.display='inline'; document.getElementById('_854_924_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_854_924_Closed_Image" onclick="this.style.display='none'; document.getElementById('_854_924_Closed_Text').style.display='none'; document.getElementById('_854_924_Open_Image').style.display='inline'; document.getElementById('_854_924_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">list.Add(newBook(title,author,price,paperBack));<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">//对于每一本平装书调用ProcessBookDelegate这个委托，以对平装书进行处理:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">publicvoidProcessPaperbackBooks(ProcessBookDelegateprocessBook)<img id="_1061_1223_Open_Image" onclick="this.style.display='none'; document.getElementById('_1061_1223_Open_Text').style.display='none'; document.getElementById('_1061_1223_Closed_Image').style.display='inline'; document.getElementById('_1061_1223_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_1061_1223_Closed_Image" onclick="this.style.display='none'; document.getElementById('_1061_1223_Closed_Text').style.display='none'; document.getElementById('_1061_1223_Open_Image').style.display='inline'; document.getElementById('_1061_1223_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">foreach(Bookbinlist)<img id="_1107_1215_Open_Image" onclick="this.style.display='none'; document.getElementById('_1107_1215_Open_Text').style.display='none'; document.getElementById('_1107_1215_Closed_Image').style.display='inline'; document.getElementById('_1107_1215_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_1107_1215_Closed_Image" onclick="this.style.display='none'; document.getElementById('_1107_1215_Closed_Text').style.display='none'; document.getElementById('_1107_1215_Open_Image').style.display='inline'; document.getElementById('_1107_1215_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">if(b.Paperback)<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">//Callingthedelegate:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">processBook(b);<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101955830.gif" align="top">}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">//使用Bookstore命名空间里的类:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">namespaceBookTestClient<img id="_1281_3033_Open_Image" onclick="this.style.display='none'; document.getElementById('_1281_3033_Open_Text').style.display='none'; document.getElementById('_1281_3033_Closed_Image').style.display='inline'; document.getElementById('_1281_3033_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954295.gif" align="top"><img id="_1281_3033_Closed_Image" onclick="this.style.display='none'; document.getElementById('_1281_3033_Closed_Text').style.display='none'; document.getElementById('_1281_3033_Open_Image').style.display='inline'; document.getElementById('_1281_3033_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954584.gif" align="top">...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">usingBookstore;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">//具有统计平装书并求出平装书的平均价格功能的类:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">classPriceTotaller<img id="_1360_1644_Open_Image" onclick="this.style.display='none'; document.getElementById('_1360_1644_Open_Text').style.display='none'; document.getElementById('_1360_1644_Closed_Image').style.display='inline'; document.getElementById('_1360_1644_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_1360_1644_Closed_Image" onclick="this.style.display='none'; document.getElementById('_1360_1644_Closed_Text').style.display='none'; document.getElementById('_1360_1644_Open_Image').style.display='inline'; document.getElementById('_1360_1644_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">intcountBooks=0;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">decimalpriceBooks=0.0m;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">internalvoidAddBookToTotal(Bookbook)<img id="_1474_1543_Open_Image" onclick="this.style.display='none'; document.getElementById('_1474_1543_Open_Text').style.display='none'; document.getElementById('_1474_1543_Closed_Image').style.display='inline'; document.getElementById('_1474_1543_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_1474_1543_Closed_Image" onclick="this.style.display='none'; document.getElementById('_1474_1543_Closed_Text').style.display='none'; document.getElementById('_1474_1543_Open_Image').style.display='inline'; document.getElementById('_1474_1543_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">countBooks+=1;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">priceBooks+=book.Price;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">internaldecimalAveragePrice()<img id="_1590_1639_Open_Image" onclick="this.style.display='none'; document.getElementById('_1590_1639_Open_Text').style.display='none'; document.getElementById('_1590_1639_Closed_Image').style.display='inline'; document.getElementById('_1590_1639_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_1590_1639_Closed_Image" onclick="this.style.display='none'; document.getElementById('_1590_1639_Closed_Text').style.display='none'; document.getElementById('_1590_1639_Open_Image').style.display='inline'; document.getElementById('_1590_1639_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">returnpriceBooks/countBooks;<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">//用以测试书籍数据库的类:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">classTest<img id="_1683_3031_Open_Image" onclick="this.style.display='none'; document.getElementById('_1683_3031_Open_Text').style.display='none'; document.getElementById('_1683_3031_Closed_Image').style.display='inline'; document.getElementById('_1683_3031_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_1683_3031_Closed_Image" onclick="this.style.display='none'; document.getElementById('_1683_3031_Closed_Text').style.display='none'; document.getElementById('_1683_3031_Open_Image').style.display='inline'; document.getElementById('_1683_3031_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">//打印书籍题目的静态方法.<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">staticvoidPrintTitle(Bookb)<img id="_1750_1805_Open_Image" onclick="this.style.display='none'; document.getElementById('_1750_1805_Open_Text').style.display='none'; document.getElementById('_1750_1805_Closed_Image').style.display='inline'; document.getElementById('_1750_1805_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_1750_1805_Closed_Image" onclick="this.style.display='none'; document.getElementById('_1750_1805_Closed_Text').style.display='none'; document.getElementById('_1750_1805_Open_Image').style.display='inline'; document.getElementById('_1750_1805_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">Console.WriteLine("{0}",b.Title);<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">//程序执行的入口：<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">staticvoidMain()<img id="_1857_2510_Open_Image" onclick="this.style.display='none'; document.getElementById('_1857_2510_Open_Text').style.display='none'; document.getElementById('_1857_2510_Closed_Image').style.display='inline'; document.getElementById('_1857_2510_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_1857_2510_Closed_Image" onclick="this.style.display='none'; document.getElementById('_1857_2510_Closed_Text').style.display='none'; document.getElementById('_1857_2510_Open_Image').style.display='inline'; document.getElementById('_1857_2510_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">BookDBbookDB=newBookDB();<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">//用几本书来输初始化书籍数据库:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">AddBooks(bookDB);<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">//打印平装书的题目:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">Console.WriteLine("PaperbackBookTitles:");<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">//创建与静态方法Test.PrintTitle关联的新的委托对象:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">bookDB.ProcessPaperbackBooks(newProcessBookDelegate(PrintTitle));<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">//通过PriceTotaller的实例获取平装书的平均价格:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">PriceTotallertotaller=newPriceTotaller();<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">//创建与对象totaller上的非静态方法AddBookToTotal关联的新的委托对象:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">bookDB.ProcessPaperbackBooks(newProcessBookDelegate(totaller.AddBookToTotal));<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">Console.WriteLine("平装书的平均价格:${0:#.##}",<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">totaller.AveragePrice());<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">//向数据库添加书以初始化书籍数据库:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">staticvoidAddBooks(BookDBbookDB)<img id="_2588_3026_Open_Image" onclick="this.style.display='none'; document.getElementById('_2588_3026_Open_Text').style.display='none'; document.getElementById('_2588_3026_Closed_Image').style.display='inline'; document.getElementById('_2588_3026_Closed_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954101.gif" align="top"><img id="_2588_3026_Closed_Image" onclick="this.style.display='none'; document.getElementById('_2588_3026_Closed_Text').style.display='none'; document.getElementById('_2588_3026_Open_Image').style.display='inline'; document.getElementById('_2588_3026_Open_Text').style.display='inline';" alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954251.gif" align="top">...{<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">bookDB.AddBook("TheCProgrammingLanguage",<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">"BrianW.KernighanandDennisM.Ritchie",19.95m,true);<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">bookDB.AddBook("TheUnicodeStandard2.0",<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">"TheUnicodeConsortium",39.95m,true);<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">bookDB.AddBook("TheMS-DOSEncyclopedia",<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">"RayDuncan",129.95m,false);<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">bookDB.AddBook("Dogbert'sCluesfortheClueless",<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954373.gif" align="top">"ScottAdams",12.00m,true);<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954638.gif" align="top">}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101955830.gif" align="top">}<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top"><img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">输出：<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">PaperbackBookTitles:<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">TheCProgrammingLanguage<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">TheUnicodeStandard2.0<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">Dogbert'sCluesfortheClueless<img alt="" src="http://dotnet.chinaitlab.com/UploadFiles_6597/200706/20070618101954857.gif" align="top">平装书的平均价格:$23.97 声明委托 以下语句： |
