文/黄忠成 ；2006/9/21
原文链接：http://blog.csdn.net/Code6421/archive/2006/09/25/1282167.aspx
整理：吕震宇
截至目前为止，本文一直以程序方式来配置ObjectBuidler建立对象所需的各种对象，但在实务上，这些动作应该是交由配置文件来负责，这样才能在不重新编译应用程序的情况下，改变其行为或增加其功能。很幸运的，Microsoft于ObjectBuilder的范例中提供了一个途径来达到此目的，该范例定义了一个.xsd文件，其内定义了ConstructorInjection、SetterInjection、Singleton、TypeMapping所需要的schema，当然！这个xsd中也定义了Strategy的schema，允许设计者通过配置文件来添加对象建立时所需使用的Strategys。
ConsturctorInjectionWithConfiguration我将Microsoft所提供可配置ObjectBuidler的范例中关于处理配置文件时的.xsd及相关文件提取出来，并添加MethodInjection时所需要的schema及程序代码，放置于本文的范例程序档中，当读者们需要使用配置文件这个功能时，可以将Config目录中的ObjectBuilderXmlConfig.xsd、ObjectBuilderXmlConfig.xsx、ObjectBuilderXmlConfig.cs、ObjectBuilderXmlConfig.Generate.cs等文件复制到项目目录中，并将ObjectBuilderXmlConfig.xsd、ObjectBuilderXmlConfig.Generate.cs加入到项目中，完成后再将ObjectBuilderXmlConfig.xsd设置成EmbeddedResource，如图10所示。
图10
接着将修改ObjectBuilderXmlConfig.cs中关于由Resource中取得.xsd内容的程序代码，修正namespace为项目的默认namespace即可。
程序44
private static ObjectBuilderXmlConfig ParseXmlConfiguration( string config) { XmlSerializer ser = new XmlSerializer( typeof(ObjectBuilderXmlConfig)); StringReader stringReader = new StringReader(config); XmlSchema schema = XmlSchema.Read(Assembly.GetExecutingAssembly().GetManifestResourceStream( "OB_CSConfigurationTest.ObjectBuilderXmlConfig.xsd"), null); XmlReaderSettings settings = new XmlReaderSettings(); settings.ValidationType = ValidationType.Schema; settings.Schemas.Add(schema); XmlReader reader = XmlReader.Create(stringReader, settings); ObjectBuilderXmlConfig configData = (ObjectBuilderXmlConfig)ser.Deserialize(reader); return configData; }要使用配置文件来完成ConstructorInjection，我们必须在项目中新增一个xml文件，内容如下所示。
<?xml version="1.0" encoding="utf-8"?><object-builder-config xmlns="pag-object-builder" > <build-rules > <build-rule type="OB_ConfigurationTest.InputAccept,OB_CSConfigurationTest" mode="Instance" > <constructor-params > <ref-param type="OB_ConfigurationTest.PromptDataProcessor,OB_CSConfigurationTest" /> </constructor-params> </build-rule> </build-rules></object-builder-config>在ObjectBuilderXmlConfig.xsd定义中，build-rules代表着此BuilderContext中所有的对象建立规则，每个build-rule对应着一个“类型/id”，类型格式为<type,Assembly>，id部份则可通过添加name这个attribute来设置，未指定时就以null为默认值，如下。
<?xml version="1.0" encoding="utf-8"?><object-builder-config xmlns="pag-object-builder" > <build-rules > <build-rule type="OB_ConfigurationTest.InputAccept,OB_CSConfigurationTest" name="id1" mode="Instance" > ......每个build-rule可以拥有一个constructor-params区段，设计者可以在这个区段中添加value-param或是ref-param定义，前者是直接设置该参数的值，后者是通过reference方式来设值，本例中是将InputAccept构造函数的第一个参数值指定为PromptDataProcessor。程序45是使用这个配置文件的程序列表。
程序45
using System; using System.Collections.Generic; using System.Text; using System.IO; using System.Configuration; using Microsoft.Practices.ObjectBuilder; using Microsoft.Practices.EnterpriseLibrary.Common.Configuration.ObjectBuilder; using Microsoft.Practices.EnterpriseLibrary.Common.Configuration; namespace OB_ConfigurationTest { class Program { static void Main( string[] args) { using (FileStream fs = new FileStream( "XmlFile1.xml", FileMode.Open, FileAccess.Read)) { using (StreamReader sr = new StreamReader(fs)) { Builder builder = new Builder(ObjectBuilderXmlConfig.FromXml(sr.ReadToEnd())); InputAccept accept = builder.BuildUp<InputAccept>( new Locator(), null, null); accept.Execute(); Console.Read(); } } } } public class InputAccept { private IDataProcessor _dataProcessor; public void Execute() { Console.Write( "Please Input some words:"); string input = Console.ReadLine(); input = _dataProcessor.ProcessData(input); Console.WriteLine(input); } public InputAccept([Dependency(Name = "dataProcessor")]IDataProcessor dataProcessor) { _dataProcessor = dataProcessor; } } public interface IDataProcessor { string ProcessData( string input); } public class DummyDataProcessor : IDataProcessor { #region IDataProcessor Members public string ProcessData( string input) { return input; } #endregion } public class PromptDataProcessor : IDataProcessor { #region IDataProcessor Members public string ProcessData( string input) { return "your input is:" + input; } #endregion } } SetterInjectionWithConfiguration同样的，我们也可以通过配置文件来完成SetterInjection，此范例所使用的配置文件如下。
<?xml version="1.0" encoding="utf-8"?> <object-builder-config xmlns="pag-object-builder" > <build-rules > <build-rule type="OB_CSPropertyInjectionTest.InputAccept,OB_CSPropertyInjectionTest" mode="Instance" > <property name="DataProcessor" > <ref-param type="OB_CSPropertyInjectionTest.PromptDataProcessor,OB_CSPropertyInjectionTest" /> </property> </build-rule> </build-rules></object-builder-config>设计者必须将要设置的属性定义放置于build-rule区段中的property，property有一个nameattribute，代表着欲设置属性的名称，如要设置一个以上的属性，只需添加多个property区段即可，程序46是使用此配置文件的程序代码。
程序46
using System; using System.Collections.Generic; using System.Text; using System.IO; using System.Configuration; using Microsoft.Practices.ObjectBuilder; using Microsoft.Practices.EnterpriseLibrary.Common.Configuration.ObjectBuilder; using Microsoft.Practices.EnterpriseLibrary.Common.Configuration; namespace OB_CSPropertyInjectionTest { class Program { static void Main( string[] args) { using (FileStream fs = new FileStream( "XmlFile1.xml", FileMode.Open, FileAccess.Read)) { using (StreamReader sr = new StreamReader(fs)) { Builder builder = new Builder(ObjectBuilderXmlConfig.FromXml(sr.ReadToEnd())); InputAccept accept = builder.BuildUp<InputAccept>( new Locator(), null, null); accept.Execute(); Console.Read(); } } } } public class InputAccept { private IDataProcessor _dataProcessor; [Dependency(Name = "DataProcessor")] public IDataProcessor DataProcessor { get { return _dataProcessor; } set { _dataProcessor = value; } } public void Execute() { Console.Write( "Please Input some words:"); string input = Console.ReadLine(); input = _dataProcessor.ProcessData(input); Console.WriteLine(input); } } public interface IDataProcessor { string ProcessData( string input); } public class DummyDataProcessor : IDataProcessor { #region IDataProcessor Members public string ProcessData( string input) { return input; } #endregion } public class PromptDataProcessor : IDataProcessor { #region IDataProcessor Members public string ProcessData( string input) { return "your input is:" + input; } #endregion } } MethodInjectionWithConfigurationMicrosoft所提供的配置文件机制并未定义MethodInjection的功能，我将其稍微修改来支持此功能，下面是MethodInjection时所用的配置文件。
<?xml version="1.0" encoding="utf-8"?> <object-builder-config xmlns="pag-object-builder" > <build-rules > <build-rule type="OB_CSPropertyInjectionTest.InputAccept,OB_CSPropertyInjectionTest" mode="Instance" > <property name="DataProcessor" > <ref-param type="OB_CSPropertyInjectionTest.PromptDataProcessor,OB_CSPropertyInjectionTest" /> </property> </build-rule> </build-rules></object-builder-config>用法与property大致相同，程序47是程序代码列表。
程序47
using System; using System.Collections.Generic; using System.Text; using System.IO; using Microsoft.Practices.ObjectBuilder; namespace OB_CSMethodInjectionTest { class Program { static void Main( string[] args) { using (FileStream fs = new FileStream( "XmlFile1.xml", FileMode.Open, FileAccess.Read)) { using (StreamReader sr = new StreamReader(fs)) { Builder builder = new Builder(ObjectBuilderXmlConfig.FromXml(sr.ReadToEnd())); InputAccept accept = builder.BuildUp<InputAccept>( new Locator(), null, null); accept.Execute(); Console.Read(); } } } } public class InputAccept { private IDataProcessor _dataProcessor; public void SetDataProcessor([Dependency(Name = "dataProcessor")]IDataProcessor dataProcessor) { _dataProcessor = dataProcessor; } public void Execute() { Console.Write( "Please Input some words:"); string input = Console.ReadLine(); input = _dataProcessor.ProcessData(input); Console.WriteLine(input); } } public interface IDataProcessor { string ProcessData( string input); } public class DummyDataProcessor : IDataProcessor { #region IDataProcessor Members public string ProcessData( string input) { return input; } #endregion } public class PromptDataProcessor : IDataProcessor { #region IDataProcessor Members public string ProcessData( string input) { return "your input is:" + input; } #endregion } } SingletonWithConfiguration通过配置文件，也可以定义那个“类型/id”的对象是使用Singleton模式，如下所示。
<build-rule type="OB_CSMethodInjectionTest.PromptDataProcessor,OB_CSMethodInjectionTest" mode="Singleton" /> TypeMappingWithConfiguration我们也可以在配置文件中定义TypeMapping，如下所示。
<build-rule type="OB_CSMethodInjectionTest.IDataProcessor,OB_CSMethodInjectionTest" mode="Instance" > <mapped-type type="OB_CSMethodInjectionTest.PromptDataProcessor,OB_CSMethodInjectionTest" /></build-rule> CustomizeStrategys通过配置文件，也可以定义建立对象时所需要的Strategys，如下所示。
<object-builder-config xmlns="pag-object-builder" > <strategies include-default="false" > <strategy type="Microsoft.Practices.ObjectBuilder.TypeMappingStrategy,Microsoft.Practices.ObjectBuilder" /> <strategy type="Microsoft.Practices.ObjectBuilder.CreationStrategy,Microsoft.Practices.ObjectBuilder" /> <strategy type="Microsoft.Practices.ObjectBuilder.MethodExecutionStrategy,Microsoft.Practices.ObjectBuilder" /> ............. </strategies></object-builder-config>include-default属性决定是否包含Builder对象所内建的Strategys。
ObjectBuilder是一个相当不错的DependencyInjection实现对象，虽然相对于Spring、Avalon，ObjectBuilder并不是相当的完整，例如没有完整的配置文件驱动特色，但它所具备的高度延展性，可以让我们轻易的达到这个需求，且日后相信ObjectBuilder也会内建这些功能的。
