本文最后更新于：2023年5月12日 下午
该 Attribute 为自定义自动依赖注入工具, 只需要在 class 中使用该 Attribute 即可以自动注入, 不必在 Program.cs 或者 Startup.cs 中手动注入.
1.创建 InjectType 枚举类
该枚举类定义三种生命周期, 分别为 Singleton, Scoped, Transient.
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public enum InjectType
{
Scope,
Single,
Transient
}
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2.创建 AutoInjectAttribute.cs 文件
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| [AttributeUsage(AttributeTargets.Class, AllowMultiple = false)]
public class AutoInjectAttribute: Attribute
{
public AutoInjectAttribute(Type interfaceType, InjectType injectType)
{
Type = interfaceType;
InjectType = injectType;
}
public Type Type { get; set; }
public InjectType InjectType { get; set; }
}
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3.创建 AutoInjectExtension.cs 文件
该文件为自动注入扩展方法类.
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| public static class AutoInjectExtension {
public static IServiceCollection AddAutoDi(this IServiceCollection serviceCollection)
{
var path = AppDomain.CurrentDomain.BaseDirectory;
var assemblies = Directory.GetFiles(path, "*.dll").Select(Assembly.LoadFrom).ToList();
foreach (var assembly in assemblies)
{
var types = assembly.GetTypes().Where(a => a.GetCustomAttribute<AutoInjectAttribute>() != null)
.ToList();
if (types.Count <= 0) continue;
foreach (var type in types)
{
var attr = type.GetCustomAttribute<AutoInjectAttribute>();
if (attr?.Type == null) continue;
switch (attr.InjectType)
{
case InjectType.Scope:
serviceCollection.AddScoped(attr.Type, type);
break;
case InjectType.Single:
serviceCollection.AddSingleton(attr.Type, type);
break;
case InjectType.Transient:
serviceCollection.AddTransient(attr.Type, type);
break;
default:
throw new ArgumentOutOfRangeException();
}
}
}
return serviceCollection;
}
}
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4.注册扩展方法
在 Program.cs 或者 Startup.cs 中注册该扩展方法.
5.使用
在需要注入的类中使用该 Attribute.
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| [AutoInject(typeof(IUserService), InjectType.Scope)]
public class UserService: IUserService {}
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