.NET中的依赖注入示例？ [英] Dependency Injection in .NET with examples?

问题描述

有人可以使用 一个基本的.NET示例解释依赖注入 ，并提供一些指向.NET资源的链接以扩展该主题？

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

这不是什么是依赖关系注意？，因为我正在询问具体的.NET示例和资源。

This is not a duplicate of What is dependency injection? because I am asking about specific .NET examples and resources.

推荐答案

这是一个常见的例子。您需要登录您的应用程序。但是，在设计时，您不确定客户端是否要登录到数据库，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，您要使用DI将该选项推迟到可由客户端配置的选项。

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

这是一些伪代码（大致基于Unity）：

This is some pseudocode (roughly based on Unity):

您创建一个记录界面：

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

然后在你的课上使用这个界面

then use this interface in your classes

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

在运行时注入这些依赖项

inject those dependencies at runtime

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

，该实例在app.config中配置： / p>

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，如果要更改记录器的类型，只需进入配置并指定其他类型。

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

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