有人能解释依赖注入 与 Basic .NET示例并提供一些链接到.NET资源，关于这个问题的延伸？

Can someone explain dependency injection with a basic .NET example and provide a few links to .NET resources to extend on the subject?

这是不是http://stackoverflow.com/questions/130794/what-is-dependency-injection因为我问具体.NET的例子和资源。

This is not a duplicate of http://stackoverflow.com/questions/130794/what-is-dependency-injection because I am asking about specific .NET examples and resources.

推荐答案

下面是一个常见的​​例子。您需要登录您的应用程序。但是，在设计时，你不知道，如果客户想登录到数据库，文件或事件日志。

Here's a common example. You need to log in your application. But, at design time, you're not sure if the client wants to log to a database, files, or the event log.

所以，你想用DI给选择推迟到一种可通过客户端进行配置。

So, you want to use DI to defer that choice to one that can be configured by the client.

这是一些伪code（约基于统一）：

This is some pseudocode (roughly based on Unity):

您创建一个日志接口：

public interface ILog
{
  void Log(string text);
}

然后使用这个接口在类中

then use this interface in your classes

public class SomeClass
{
  [Dependency]
  public ILog Log {get;set;}
}

注入这些依赖在运行时

inject those dependencies at runtime

public class SomeClassFactory
{
  public SomeClass Create()
  {
    var result = new SomeClass();
    DependencyInjector.Inject(result);
    return result;
  }
}

和实例配置中的app.config：

and the instance is configured in app.config:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <section name ="unity"
             type="Microsoft.Practices.Unity.Configuration.UnityConfigurationSection,
              Microsoft.Practices.Unity.Configuration"/>
  </configSections>
  <unity>
    <typeAliases>
      <typeAlias alias="singleton"
                 type="Microsoft.Practices.Unity.ContainerControlledLifetimeManager,Microsoft.Practices.Unity" />
    </typeAliases>
    <containers>
      <container>
        <types>
          <type type="MyAssembly.ILog,MyAssembly"
                mapTo="MyImplementations.SqlLog, MyImplementations">
            <lifetime type="singleton"/>
          </type>
        </types>
      </container>
    </containers>
  </unity>
</configuration>

现在，如果你想改变记录器的类型，你只要进入配置，并指定另一种类型。

Now if you want to change the type of logger, you just go into the configuration and specify another type.