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

问题描述

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

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 什么是依赖注入? 因为我问的是特定的.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，您不确定客户端是要记录到数据库、文件还是事件日志.

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.

因此，您希望使用 DI 将该选项推迟到客户端可以配置的选项.

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):

你创建一个日志接口:

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

然后在你的类中使用这个接口

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

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

并且实例是在 app.config 中配置的:

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，你只需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.

这篇关于.NET 中的依赖注入示例?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！