按部就班学.Net Core Web Api开发系列【10】：使用日志

系列目录

按部就班学.Net Core Web Api开发系列目录

 本系列涉及到的源码下载地址：https://github.com/seabluescn/Blog_WebApi

 

1、本篇概述

本篇介绍日志的使用，包括系统默认的控制台日志和第三方NLog日志管理。

 

2、使用系统控制台日志

一、使用内置日志

    [Produces("application/json")]
    [Route("api/Article")]
    public class ArticleController : Controller
    {      private readonly ILogger _logger;
        public ArticleController(SalesContext context, ILogger<ArticleController> logger)
        {          
            _logger = logger;
        }       

        [HttpGet("logger")]
        public void TestLogger()
        {
            _logger.LogCritical("LogCritical");
            _logger.LogError("LogError");          
            _logger.LogWarning("LogWarning");
            _logger.LogInformation("LogInformation");
            _logger.LogDebug("LogDebug");

            return;
        }
    }

默认只能看到前三条记录：

主要缘由是日志的最低级别默认为Warring，若是要显示其余级别日志，须要修改application.json文件。 

{  
  "Logging": {
    "IncludeScopes": false,
    "Debug": {
      "LogLevel": {
        "Default": "Error"
      }
    },
    "Console": {
      "LogLevel": {
        "Default": "Information"
      }
    }
  }
}

日志级别优先级以下顺序：

Critical > Error > Warning > Information > Debug

调整日志级别为Information 或Debug之后会显示太多无关的日志信息，能够配置默认级别为Warring，而本身项目命名空间的日志级别为Debug。

"Console": {
      "LogLevel": {
        "Default": "Warning",
        "SaleService.Controllers": "DEBUG"
      }
    }

 

二、几点说明

1）目前日志已经能够正常工做了，把项目发布到Linux环境下，经过配置Supervisor能够把控制台的内容输出到文件系统，建议在调试环境下采用Debug日志级别，而在生成环境采用Error日志级别。配置Supervisor的内容能够参考：按部就班学.Net Core Web Api开发系列【7】：项目发布。

 2）若是稍微了解依赖注入（DI）的知识，就能够理解咱们在Controoler中使用ILogger是采用标准的构造函数注入的方式，可是问题是用户并无注册该服务，实际上是系统在CreateDefaultBuilder时帮咱们注册了日志服务。能够看几段源码的片断：

CreateDefaultBuilder：

using System;
using System.IO;
using System.Reflection;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Routing;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;

namespace Microsoft.AspNetCore
{   
    public static class WebHost
    { 
        public static IWebHostBuilder CreateDefaultBuilder(string[] args)
        {
            return WebHostBuilderIISExtensions.UseIISIntegration(HostingAbstractionsWebHostBuilderExtensions.UseContentRoot(WebHostBuilderKestrelExtensions.UseKestrel(new WebHostBuilder()), Directory.GetCurrentDirectory()).ConfigureAppConfiguration(delegate(WebHostBuilderContext hostingContext, IConfigurationBuilder config)
            {
                IHostingEnvironment hostingEnvironment = hostingContext.HostingEnvironment;
                JsonConfigurationExtensions.AddJsonFile(JsonConfigurationExtensions.AddJsonFile(config, "appsettings.json", true, true), string.Format("appsettings.{0}.json", hostingEnvironment.EnvironmentName), true, true);
                if (HostingEnvironmentExtensions.IsDevelopment(hostingEnvironment))
                {
                    Assembly assembly = Assembly.Load(new AssemblyName(hostingEnvironment.ApplicationName));
                    if (assembly != null)
                    {
                        UserSecretsConfigurationExtensions.AddUserSecrets(config, assembly, true);
                    }
                }
                EnvironmentVariablesExtensions.AddEnvironmentVariables(config);
                if (args != null)
                {
                    CommandLineConfigurationExtensions.AddCommandLine(config, args);
                }
            }).ConfigureLogging(delegate(WebHostBuilderContext hostingContext, ILoggingBuilder logging)
            {
                LoggingBuilderExtensions.AddConfiguration(logging, hostingContext.Configuration.GetSection("Logging")); logging.AddConsole(); logging.AddDebug();
            })).UseDefaultServiceProvider(delegate(WebHostBuilderContext context, ServiceProviderOptions options)
            {
                options.ValidateScopes = HostingEnvironmentExtensions.IsDevelopment(context.HostingEnvironment);
            });
        }
    }
}

AddConsole：

using System;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging.Console;

namespace Microsoft.Extensions.Logging
{   
    public static class ConsoleLoggerExtensions
    {       
        public static ILoggingBuilder AddConsole(this ILoggingBuilder builder)
        {
            builder.Services.AddSingleton<ILoggerProvider, ConsoleLoggerProvider>();
            return builder;
        }       
    }
}

 

3、使用NLog

一、经过NuGet获取包：NLog.Web.AspNetCore

二、修改Startup类的Configure方法：

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

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
        {
            loggerFactory.AddNLog();            
            loggerFactory.ConfigureNLog("nlog.config"); //若是采用默认配置文件nlog.config，该语句能够省略
        }
    }

nlog.config配置文件内容以下：

<?xml version="1.0" encoding="utf-8"?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <targets>
    <target xsi:type="File" name="logfile" fileName="${basedir}/logs/${shortdate}_all.log" keepFileOpen="false" layout="${longdate}|${callsite:fileName=True}|${uppercase:${level}}|${message} ${exception}" />
    <target xsi:type="File" name="debugfile" fileName="${basedir}/logs/${shortdate}_debug.log" keepFileOpen="false" layout="${longdate}|${callsite:fileName=True}|${uppercase:${level}}|${message} ${exception}" />
    <target xsi:type="File" name="errfile" fileName="${basedir}/logs/${shortdate}_error.log" keepFileOpen="false" layout="${longdate}|${callsite:fileName=True}|${uppercase:${level}}|${message} ${exception}" />
  </targets>
  <rules>
    <logger name="*" level="Debug" writeTo="debugfile" />
    <logger name="*" level="Error" writeTo="errfile" />    
    <logger name="*" minlevel="Trace" writeTo="logfile" />
  </rules>
</nlog>

项目发布时修改配置文件，只保留errfile便可。

以上就是所有代码，Controller中的代码无需修改。

 

三、两个注意点

1）目前咱们已经采用NLog来进行日志的记录，此时系统默认的日志仍然是正常工做的，项目发布时建议把系统默认的日志级别改为Error，nlog的输出日志只保留errfile，以避免形成服务器磁盘空间浪费。

2）项目发布时nlog.config文件可能不会发布到目标目录，须要修改该文件的文件属性：