ASP.NET Core 3中的自定义日志记录

根据我的经验，通常在API中记录请求和响应。这样做可以帮助开发人员调试问题并提供有价值的性能指标。在本教程中，我将介绍如何为ASP.NET Core 3 Web API创建基本的日志记录解决方案。在这篇文章的结尾，我们将有一个有效的日志记录解决方案，它将记录每个请求以及对控制台和文件系统的响应，并且日志将包括API处理每个请求所花费的时间。以下是概述：

1. 先决条件
2. 创建RequestLog和ResponseLog模型
3. 创建ILogForWebAPI
4. 创建WebAPIConsoleLogger
5. 创建WebAPIFileLogger
6. 创建CustomLoggingMiddleware
7. 在启动中添加自定义日志记录，然后进行测试

先决条件

您应该熟悉 ASP.NET Core Web API请求管道。

首先，创建一个ASP.NET Core 3 Web API项目。

创建RequestLog和ResponseLog模型

这些类将携带我们要记录的请求和响应数据。

 public class RequestLog
    {
        public Guid Id { get; set; }
        public string Action { get; set; }
        public string URL { get; set; }
        public string IPAddress { get; set; }
        public DateTime TimeStampUtc { get; set; }
    }

 public class ResponseLog
{
        public Guid Id { get; set; }
        public string Action { get; set; }
        public string URL { get; set; }
        public int StatusCode { get; set; }
        public long ResponseTimeInMilliseconds { get; set; }
        public DateTime TimeStampUtc { get; set; }
}

创建ILogForWebAPI

在这里，我们创建了可以执行两个操作的日志记录抽象—日志记录请求和日志记录响应。

 public interface ILogForWebAPIs
    {
        Task LogAsync(RequestLog requestLog);
        Task LogAsync(ResponseLog responseLog);
    }

创建WebAPIConsoleLogger

遵循单一职责原则（SRP），我们将创建ILogForWebAPI的两个实现。WebAPIConsoleLogger将负责登录到控制台，而WebAPIFileLogger将负责登录到文件系统。我们可以使用Decorator Pattern在单个ILogForWebAPI实例中提供两个记录器的功能。每个ILogForWebAPIs实现都将包含ILogForWebAPIs的嵌套实例，如果该实例不为null，则将其调用。

 public class WebAPIConsoleLogger : ILogForWebAPIs
    {
        private readonly ILogForWebAPIs _nextLogger;
        private readonly string _dateTimeFormat = "hh:mm:ss tt";

        public WebAPIConsoleLogger(ILogForWebAPIs nextLogger = null)
        {
            _nextLogger = nextLogger;
        }

        public async Task LogAsync(RequestLog requestLog)
        {
            Console.WriteLine($"Request received from {requestLog.IPAddress} @ {requestLog.TimeStampUtc.ToString(_dateTimeFormat)} (Utc)");
            Console.WriteLine($"{requestLog.Action} {requestLog.URL}");
            Console.WriteLine();

            if (_nextLogger != null)
            {
                await _nextLogger.LogAsync(requestLog);
            }
        }

        public async Task LogAsync(ResponseLog responseLog)
        {
            Console.WriteLine($"Response sent @ {responseLog.TimeStampUtc.ToString(_dateTimeFormat)} (Utc)");
            Console.WriteLine($"{responseLog.StatusCode}: {responseLog.Action} {responseLog.URL}");
            Console.WriteLine($"Response time: {responseLog.ResponseTimeInMilliseconds} ms");
            Console.WriteLine();

            if (_nextLogger != null)
            {
                await _nextLogger.LogAsync(responseLog);
            }
        }
    }

创建WebAPIFileLogger

WebAPIFileLogger将序列化模型并将其ID用作文件名，从而为每个请求和响应创建一个json文件。

 public class WebAPIFileLogger : ILogForWebAPIs
    {
        private readonly string _requestDirectory;
        private readonly string _responseDirectory;
        private readonly ILogForWebAPIs _nextLogger;

        public WebAPIFileLogger(string path, ILogForWebAPIs nextLogger = null)
        {
            if (string.IsNullOrWhiteSpace(path))
            {
                throw new ArgumentNullException(nameof(path));
            }

            _requestDirectory = Path.Combine(path, "requests");
            _responseDirectory = Path.Combine(path, "responses");

            if (!Directory.Exists(_requestDirectory))
            {
                Directory.CreateDirectory(_requestDirectory);
            }

            if (!Directory.Exists(_responseDirectory))
            {
                Directory.CreateDirectory(_responseDirectory);
            }

            _nextLogger = nextLogger;
        }

        public async Task LogAsync(RequestLog requestLog)
        {
            var serializedLog = JsonConvert.SerializeObject(requestLog, Formatting.Indented);
            var filePath = Path.Combine(_requestDirectory, $"{requestLog.Id}.json");
            await File.WriteAllTextAsync(filePath, serializedLog);

            if (_nextLogger != null)
            {
                await _nextLogger.LogAsync(requestLog);
            }
        }

        public async Task LogAsync(ResponseLog responseLog)
        {
            var serializedLog = JsonConvert.SerializeObject(responseLog, Formatting.Indented);
            var filePath = Path.Combine(_responseDirectory, $"{responseLog.Id}.json");
            await File.WriteAllTextAsync(filePath, serializedLog);

            if (_nextLogger != null)
            {
                await _nextLogger.LogAsync(responseLog);
            }
        }
    }

创建CustomLoggingMiddleware

CustomLoggingMiddleware需要将自身附加到请求管道，然后使用ApplicationServices提供的记录器记录请求，最后执行请求管道并记录响应。

 public static class CustomLoggingMiddleware
    {
        public static void UseCustomLogging(this IApplicationBuilder app)
        {
            app.Use(async (context, next) =>
            {
                var logger = app.ApplicationServices.GetService<ILogForWebAPIs>();

                if (logger is null)
                {
                    throw new Exception($"Add ILogForWebAPIs to your service provider in {nameof(Startup)}.{nameof(Startup.ConfigureServices)}");
                }

                await LogRequestAsync(context, logger);
                var stopWatch = new Stopwatch();
                stopWatch.Start();

                // execute request pipeline
                await next?.Invoke();

                stopWatch.Stop();

                await LogResponseAsync(context, stopWatch.ElapsedMilliseconds, logger);
            });
        }

        private static async Task LogRequestAsync(HttpContext context, ILogForWebAPIs logger)
        {
            var requestLog = new RequestLog
            {
                Id = Guid.NewGuid(),
                Action = context.Request.Method,
                URL = context.Request.Path,
                IPAddress = context.Request.HttpContext.Connection.RemoteIpAddress.ToString(),
                TimeStampUtc = DateTime.UtcNow
            };

            await logger.LogAsync(requestLog);
        }

        private static async Task LogResponseAsync(HttpContext context, long responseTimeInMilliseconds, ILogForWebAPIs logger)
        {
            var responseLog = new ResponseLog
            {
                Id = Guid.NewGuid(),
                Action = context.Request.Method,
                URL = context.Request.Path,
                StatusCode = context.Response.StatusCode,
                ResponseTimeInMilliseconds = responseTimeInMilliseconds,
                TimeStampUtc = DateTime.UtcNow
            };

            await logger.LogAsync(responseLog);
        }
    }

在启动中添加自定义日志记录，然后进行测试

要获取我们的API日志记录，我们只需要做两件事：

1. 将记录器添加到Startup.ConfigureServices中的IServiceCollection中
2. 在Startup.Configure中调用UseCustomLogging

注意：如果像下面的示例那样使用https重定向，建议将自定义日志记录添加到请求管道中。这样，您可以确保不记录重定向。

 public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllers();
            services.AddTransient<ILogForWebAPIs>((serviceProvider) => new WebAPIConsoleLogger(new WebAPIFileLogger("APILogs")));
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseHttpsRedirection();

            app.UseCustomLogging();

            app.UseRouting();

            app.UseAuthorization();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }

要在Visual Studio中查看控制台输出，请使用项目配置文件运行应用程序并进行测试。

导航到日志目录以检查日志文件

{
“ Id”：“ 0c7ffe14-66c3-428c-bffe-0da1dccd9546”，
“ Action”：“ GET”，
“ URL”：“ / weatherforecast”，
“ IPAddress”：“ :: 1”，
“ TimeStampUtc”：“ 2020 -02-13T15：05：27.3373827Z”
}