2.2.2 核心模块--日志

• ILogger 的使用

• 日志的 ID

• 日志的分类

• 日志的级别

• LoggerProvider

• 日志的最佳实践

.NET Core 和 ASP.NET Core 中的日志记录：https://docs.microsoft.com/zh-cn/aspnet/core/fundamentals/logging/?view=aspnetcore-5.0

ILogger 的使用

在 Get 方法中添加日志

WeatherForecastController.cs

private readonly ILogger<WeatherForecastController> _logger;public WeatherForecastController(ILogger<WeatherForecastController> logger)
{_logger = logger;
}_logger.LogInformation("Get action executed");

日志的 ID

_logger.LogInformation(new EventId(1001, "Action"), "Get action executed");

日志的分类

根据不同的类名区分

private readonly ILogger<WeatherForecastController> _logger;
private readonly ILogger _myLogger;public WeatherForecastController(ILogger<WeatherForecastController> logger, ILoggerFactory loggerFactory)
{_logger = loggerFactory.CreateLogger<WeatherForecastController>();_myLogger = loggerFactory.CreateLogger("MyLogger");// 通过自己的分类 MyLogger 创建
}

日志的级别

LoggerProvider

源码：https://github.com/aspnet/Logging/tree/master/src/

ILoggerProvider.cs

using System;namespace Microsoft.Extensions.Logging
{/// <summary>/// Represents a type that can create instances of <see cref="ILogger"/>./// </summary>public interface ILoggerProvider : IDisposable{/// <summary>/// Creates a new <see cref="ILogger"/> instance./// </summary>/// <param name="categoryName">The category name for messages produced by the logger.</param>/// <returns></returns>ILogger CreateLogger(string categoryName);}
}

日志的设计模式

支持不同类型的日志输出，可以自定义一个 LoggerProvider

打印容器中所有注入的 LoggerProvider

Program.cs

var providers = host.Services.GetServices<ILoggerProvider>();// 获取容器中所有注入的实例
foreach (var provider in providers)
{Console.WriteLine(provider.GetType().ToString());
}

启动程序，输出如下：

Microsoft.Extensions.Logging.Console.ConsoleLoggerProvider
Microsoft.Extensions.Logging.Debug.DebugLoggerProvider
Microsoft.Extensions.Logging.EventSource.EventSourceLoggerProvider
Microsoft.Extensions.Logging.EventLog.EventLogLoggerProvider

添加，清除

public static IHostBuilder CreateHostBuilder(string[] args) =>Host.CreateDefaultBuilder(args).ConfigureLogging((ctx, logger) =>{//logger.AddProvider();// 添加logger.ClearProviders();// 清除})

日志的最佳实践

先注释清除代码

//.ConfigureLogging((ctx, logger) =>
//{
//    //logger.AddProvider();// 添加
//    logger.ClearProviders();// 清除
//})

在 appsettings.json 调整日志级别为 Trace

{"Logging": {"LogLevel": {"Default": "Trace","Microsoft": "Trace","Microsoft.Hosting.Lifetime": "Trace"}}
}

在 WeatherForecastController 中添加一个方法，根据需求使用日志

public IActionResult CreateOrder(dynamic order)
{_logger.LogTrace("Enter CreateOrder method");_logger.LogDebug("Start creating order: {0}", "order info");_logger.LogTrace("Start executing _orderService.Create method");if (order.amount <= 0){_logger.LogWarning("Order Amount is:{0}");}_orderService.Create(order);_logger.LogTrace("Completed executing _orderService.Crete method");_logger.LogTrace("Leave CreateOrder Successfully");_logger.LogInformation("Leave CreateOrder Successfully");return Ok();
}

GitHub源码链接：

https://github.com/MINGSON666/Personal-Learning-Library/tree/main/ArchitectTrainingCamp/HelloApi

课程链接

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