7. 依赖注入

7. 依赖注入

Masa的依赖注入系统是基于Microsoft的依赖注入扩展库(Microsoft.Extensions.DependencyInjection nuget包)开发的,因此,它的文档在Masa中也是有效的。

按照约定的注册

Masa引入了按照约定进行服务注册,依据约定大于配置,开发者无需做任何事,框架会自动完成注册

依赖接口

  • ISingletonDependency: 注册生命周期为Singleton的服务
  • IScopedDependency: 注册生命周期为Scoped的服务
  • ITransientDependency: 注册生命周期为Transient的服务
  • IAutoFireDependency: 自动触发(与ISingletonDependency、IScopedDependency、ITransientDependency结合使用,在服务自动注册结束后触发一次获取服务操作,仅继承IAutoFireDependency不起作用)

示例:

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public class StorageOptions : ITransientDependency
{

}

特性

IgnoreInjection

忽略注入,用于排除不被自动注入

  • Cascade: 设置为true时,当前类以及子类都不再被自动注册,设置为false,仅当前类不被自动注册(默认false)

示例:

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public class BaseService : ISingletonDependency
{
public static int Count { get; set; } = 0;

public BaseService()
{
Count++;
}

public BaseService(bool isChildren)
{

}
}

[IgnoreInjection]
public class GoodsBaseService : BaseService
{
public GoodsBaseService() : base(true)
{
}
}

public class GoodsService : GoodsBaseService
{
public static int GoodsCount { get; set; } = 0;

public GoodsService()
{
GoodsCount++;
}
}

效果等同于:services.AddSingleton<BaseService>(); services.AddSingleton<GoodsService>();

Dependency

配合ISingletonDependency、IScopedDependency、ITransientDependency使用,实现服务仅被注册一次

  • TryRegister: 设置true则仅当服务未注册时才会被注册,类似IServiceCollection的TryAdd … 扩展方法.

示例:

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public interface ICache : ISingletonDependency
{
void Set(string key, string value);
}

[Dependency(TryRegister = true)]
public class EmptyCache : ICache
{
public void Set(string key, string value)
{
throw new NotSupportedException($"暂不支持{nameof(Set)}方法");
}
}

public class MemoryCache : ICache
{
private readonly ConcurrentDictionary<string, Lazy<string>> _dicCache = new();

public void Set(string key, string value)
{
_ = _dicCache.AddOrUpdate
(
key,
k => new Lazy<string>(() => value, LazyThreadSafetyMode.ExecutionAndPublication),
(_, _) => new Lazy<string>(() => value, LazyThreadSafetyMode.ExecutionAndPublication)
).Value;
}
}

效果等同于:services.AddSingleton<ICache, MemoryCache>();

  • ReplaceServices: 设置true则替换之前已经注册过的服务,类似IServiceCollection的Replace … 扩展方法.

示例:

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public interface IEncryptionService : ISingletonDependency
{
string MethodName { get; }
}

[Dependency(ReplaceServices = true)]
public class Sha1EncryptionService : IEncryptionService
{
public string MethodName => "Sha1";
}

public class Md5EncryptionService : IEncryptionService
{
public string MethodName => "Md5";
}

效果等同于:services.AddSingleton<IEncryptionService, Sha1EncryptionService>();

快速入门

  1. 新建单元测试项目Assignment.DependencyInjection,选择MSTest,并安装Masa.Utils.Extensions.DependencyInjection

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    dotnet new xunit -o Assignment.DependencyInjection
    cd Assignment.DependencyInjection
    dotnet add package Masa.Utils.Extensions.DependencyInjection --version 0.5.0-preview.2
  2. 新建类StorageOptions

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    public class StorageOptions : ITransientDependency
    {

    }
  3. 新建类DITest

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    [TestClass]
    public class DITest
    {
    private IServiceCollection _services;

    [TestInitialize]
    public void Init()
    {
    _services = new ServiceCollection();
    _services.AddAutoInject();//执行自动注入
    }

    [TestMethod]
    public void TestAutoInject()
    {
    Assert.IsTrue(_services.Any<StorageOptions>(ServiceLifetime.Transient));//判断StorageOptions注册成功,且生命周期为Transient
    }

    private IServiceProvider ServiceProvider => _services.BuildServiceProvider();
    }

总结

如果需要使用按照约定自动注册服务,则请记住

  • 根据业务需要,则指定类或接口中实现以下接口
    • ISingletonDependency 单例(项目启动后仅初始化一次)
    • IScopedDependency 请求 (每次请求仅初始化一次)
    • ITransientDependency 瞬时(每次获取都会被初始化)
  • 抽象类不会被自动注册
  • 如果你有一个自定义接口IRepository,且希望接口以及对应的默认实现类RepositoryBase会被自动注册生命周期为Scoped,则接口IRepository应该继承IScopedDependency
    • 如果你希望默认提供的RepositoryBase可以被用户定义的类替换,则应该在RepositoryBase上方增加[Dependency(TryRegister = true)],那用户仅需要实现IRepository即可
    • 或不更改默认提供的RepositoryBase,用户实现IRepository后,并在新的实现类上方增加[Dependency(ReplaceServices = true)]

本章源码

Assignment07

https://github.com/zhenlei520/MasaFramework.Practice

开源地址

MASA.BuildingBlocks:https://github.com/masastack/MASA.BuildingBlocks

MASA.Contrib:https://github.com/masastack/MASA.Contrib

MASA.Utils:https://github.com/masastack/MASA.Utils

MASA.EShop:https://github.com/masalabs/MASA.EShop

MASA.Blazor:https://github.com/BlazorComponent/MASA.Blazor

如果你对我们的 MASA Framework 感兴趣,无论是代码贡献、使用、提 Issue,欢迎联系我们

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作者

MASA

发布于

2022-06-07

更新于

2022-09-26

许可协议