.NET Core DI 和子类

Question

这里是 .NET Core 的新手。我已经搜索了另一个文档、线程或指南来回答我的问题，但找不到，如果你认为有，请指出。

我正在尝试使用 DI 创建一个简单的 .NET 5 控制台应用程序，但实际上却陷入了使用日志记录构建 classes 的困境。

这是在 .NET Core 中使用 DI 将记录器（或任何其他服务）传递给子 class 的正确方法吗？按照下面的代码，在我的父 class 构造函数中，我为每个子 class 例如获取一个额外的 ILogger。 ILogger<SubClass>?
```
public TestClass(ILogger<TestClass> log, ILogger<SubClass> subClassLog, IConfiguration config)
```
如何在静态过程中初始化记录器 StaticProc？
```
public static async Task<bool> StaticProc()
```

Program.cs:


    using Microsoft.Extensions.Configuration;
    using Microsoft.Extensions.DependencyInjection;
    using Microsoft.Extensions.Hosting;
    using Microsoft.Extensions.Logging;
    using System;
    using System.IO;
    using System.Threading.Tasks;
    
    namespace ConsoleApp1
    {
        class Program
        {
            static async Task Main(string[] args)
            {
                var builder = new ConfigurationBuilder();
                BuildConfig(builder);
    
                var host = Host.CreateDefaultBuilder()
                    .ConfigureServices((context, services) =>
                    {
                        services.AddTransient<ITestClass, TestClass>();
                        services.AddTransient<ISubClass, SubClass>();
                    })
                    .ConfigureLogging(logBuilder =>
                    {
                        logBuilder.SetMinimumLevel(LogLevel.Trace);
                        logBuilder.AddLog4Net("log4net.config");
                    })
                    .Build();
    
                var log = host.Services.GetService<ILoggerFactory>().CreateLogger<Program>();
    
                log.LogInformation($"Application Started");
    
                var svc = ActivatorUtilities.CreateInstance<TestClass>(host.Services);
                await svc.Run();
    
                log.LogInformation($"Application Ended");
            }
    
            static void BuildConfig(IConfigurationBuilder builder)
            {
                builder.SetBasePath(Directory.GetCurrentDirectory())
                    .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
                    .AddJsonFile($"appsettings.{Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT") ?? "Development"}.json", optional: true)
                    .AddEnvironmentVariables();
            }
        }
    }

TestClass.cs:


    using Microsoft.Extensions.Configuration;
    using Microsoft.Extensions.Logging;
    using System.Threading.Tasks;
    
    namespace ConsoleApp1
    {
        public class TestClass : ITestClass
        {
            private readonly ILogger<TestClass> _log;
            private readonly ILogger<SubClass> _subClassLog;
            private readonly IConfiguration _config;
    
            public TestClass(ILogger<TestClass> log, ILogger<SubClass> subClassLog, IConfiguration config)
            {
                _log = log;
                _subClassLog = subClassLog;
                _config = config;
            }
    
            public async Task Run()
            {
                for (int i = 0; i < _config.GetValue<int>("Loop"); i++)
                    _log.LogDebug("Loop debug {loopNumber}", i);
    
                for (int i = 0; i < _config.GetValue<int>("Loop"); i++)
                    _log.LogInformation("Loop info {loopNumber}", i);
    
                for (int i = 0; i < _config.GetValue<int>("Loop"); i++)
                    _log.LogWarning("Loop warn {loopNumber}", i);
    
                for (int i = 0; i < _config.GetValue<int>("Loop"); i++)
                    _log.LogError("Loop error {loopNumber}", i);
    
                for (int i = 0; i < _config.GetValue<int>("Loop"); i++)
                    _log.LogCritical("Loop critical {loopNumber}", i);
    
                var subClass = new SubClass(_subClassLog, _config);
                await subClass.AnotherProc();
    
                await SubClass.StaticProc();
            }
        }
    }

SubClass.cs:


    using Microsoft.Extensions.Configuration;
    using Microsoft.Extensions.Logging;
    using System;
    using System.Threading.Tasks;
    
    namespace ConsoleApp1
    {
        public class SubClass : ISubClass
        {
            private readonly ILogger<SubClass> _log;
            private readonly IConfiguration _config;
    
            public SubClass(ILogger<SubClass> log, IConfiguration config)
            {
                _log = log;
                _config = config;
            }
    
            public async Task AnotherProc()
            {
                for (int i = 0; i < _config.GetValue<int>("Loop"); i++)
                    _log.LogDebug("Loop debug {loopNumber}", i);
    
                for (int i = 0; i < _config.GetValue<int>("Loop"); i++)
                    _log.LogInformation("Loop info {loopNumber}", i);
    
                for (int i = 0; i < _config.GetValue<int>("Loop"); i++)
                    _log.LogWarning("Loop warn {loopNumber}", i);
    
                for (int i = 0; i < _config.GetValue<int>("Loop"); i++)
                    _log.LogError("Loop error {loopNumber}", i);
    
                for (int i = 0; i < _config.GetValue<int>("Loop"); i++)
                    _log.LogCritical("Loop critical {loopNumber}", i);
            }
    
            public static async Task<bool> StaticProc()
            {
                var returnBool = true;
    
                try
                {
                    throw new Exception("");
                }
                catch (Exception ex)
                {
                    returnBool = false;
    
                    // No instance, so no _log exception.
                    // How to create standalone ILogger?
                }
    
                return returnBool;
            }
        }
    }

appsettings.json:


    {
      "Loop": 15
    }

log4net.config:


    <?xml version="1.0" encoding="utf-8"?>
    <log4net>
        <appender name="Info" type="log4net.Appender.RollingFileAppender">
            <threshold value="DEBUG" />
            <param name="File" value="App_Data\Log\Info.log"/>
            <param name="AppendToFile" value="true"/>
            <maximumFileSize value="5120KB"/>
            <lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
            <maxSizeRollBackups value="1000"/>
            <layout type="log4net.Layout.PatternLayout">
                <conversionPattern value="%d{yyyy-MM-dd HH:mm:ss} - [%t] %-5p %c %x - %m%n" />
            </layout>
        </appender>
        <appender name="Error" type="log4net.Appender.RollingFileAppender">
            <threshold value="Error" />
            <param name="File" value="App_Data\Log\Error.log"/>
            <param name="AppendToFile" value="true"/>
            <maximumFileSize value="5120KB"/>
            <lockingModel type="log4net.Appender.FileAppender+MinimalLock" />
            <maxSizeRollBackups value="1000"/>
            <layout type="log4net.Layout.PatternLayout">
                <conversionPattern value="%d{yyyy-MM-dd HH:mm:ss} - [%t] %-5p %c %x - %m%n" />
            </layout>
        </appender>
        <root>
            <appender-ref ref="Info" />
            <appender-ref ref="Error" />
        </root>
    </log4net>

Answer 1

总结

您也可以注入 ILoggerFactory 而不是 ILogger:

public TestClass(ILoggerFactory loggerFactory, IConfiguration config)
{
     // create a class logger
     _log = loggerFactory.CreateLogger<TestClass>();

     // and whenever you need a new instance of a special class logger use this:
     _subClassLog = loggerFactory.Create<SubTestClass>();
     _config = config;
}

但请注意，这会创建一个新的 ILogger 实例。 Logging in asp net core 在您的情况下，如果您确实需要带有记录器的静态方法，则仅当它已经存在时才创建它：

private static readonly ILogger<SubClass> _log;
private readonly IConfiguration _config;

public SubClass(ILoggerFactory loggerFactory, IConfiguration config)
{
     _log = _log ??= loggerFactory.CreateLogger<SubClass>();
     _config = config;
}

但我会更喜欢或更好地建议您在没有静态的情况下这样做，只需将服务注册为单例即可。

示例 1

我在这里添加了一个完整的例子：dotnet fiddle Example 1 还有像评论中提到的控制台应用程序的工作 DI。

示例 2

我觉得你不应该将它与静态方法一起使用。看看我这里的第二个例子 dotnet fiddle Example 2

.NET Core DI 和子类

.NET Core DI and sub classes

c#

log4net

dependency-injection

.net-core

asp.net-core-5.0

总结

示例 1

示例 2

.NET Core DI 和子 类

.NET Core DI and sub classes

c#

log4net

dependency-injection

.net-core

asp.net-core-5.0

总结

示例 1

示例 2

.NET Core DI 和子类