背景

　　之前一直有朋友问，.Net Core + Linux环境有没有类似Windows服务的东西。其实是有的，我了解的方法有两种：

　　#1 创建一个ASP.Net Core的Web项目（如Web API），然后通过添加中间件（Middleware）的方式来启动任务；

　　#2 创建一个.Net Core的项目，添加Host，Dependency Injection，Configuration等组件，然后通过Main方法或中间件的方式启动服务。

　　但是，上述两种方法都有点不足，如：

　　#1 会把Web的生命周期引进来，但实际上，我们并不需要Web的功能，如Controller；

　　#2 本身是没有问题的，但是对开发者的要求相对高一点点，需要对.Net Core的各个组成部分都有一定的认识，简而言之，门槛有一丢丢高。

　　.Net Core 2.1推出了一个Generic Host的概念，可以很好的解决上面两种方法的不足：

　　至于为什么选择Quartz来做调度，我想可能是因为情怀吧，因为之前是用的TopShelf+Quartz，其实Hangfire也不错。

使用Hosted Service

1. 创建一个控制台程序。

2. 添加Host Nuget包。

Install-Package Microsoft.Extensions.Hosting -Version 2.1.0
Install-Package Microsoft.Extensions.Configuration.FileExtensions -Version 2.1.0
Install-Package Microsoft.Extensions.Configuration.Json -Version 2.1.0
Install-Package Microsoft.Extensions.Configuration.EnvironmentVariables -Version 2.1.0
Install-Package Microsoft.Extensions.Configuration.CommandLine -Version 2.1.0
Install-Package Microsoft.Extensions.Logging.Console -Version 2.1.0
Install-Package Microsoft.Extensions.Logging.Debug -Version 2.1.0

3. 添加一个基于Timer的简单Hosted Service（用于简单演示），继承IHostedService。

internal class TimedHostedService : IHostedService, IDisposable {     private readonly ILogger _logger;     private Timer _timer;      public TimedHostedService(ILogger<TimedHostedService> logger)     {         _logger = logger;     }      public Task StartAsync(CancellationToken cancellationToken)     {         _logger.LogInformation("Timed Background Service is starting.");          _timer = new Timer(DoWork, null, TimeSpan.Zero, TimeSpan.FromSeconds(5));          return Task.CompletedTask;     }      private void DoWork(object state)     {         _logger.LogInformation(string.Format("[{0:yyyy-MM-dd hh:mm:ss}]Timed Background Service is working.", DateTime.Now));     }      public Task StopAsync(CancellationToken cancellationToken)     {         _logger.LogInformation("Timed Background Service is stopping.");          _timer?.Change(Timeout.Infinite, 0);          return Task.CompletedTask;     }      public void Dispose()     {         _timer?.Dispose();     } }

4. Main函数中添加Host的相关代码。

var host = new HostBuilder()     .ConfigureHostConfiguration(configHost =>     {         configHost.SetBasePath(Directory.GetCurrentDirectory());
        //configHost.AddJsonFile("hostsettings.json", true, true);         configHost.AddEnvironmentVariables("ASPNETCORE_");         //configHost.AddCommandLine(args);     })     .ConfigureAppConfiguration((hostContext, configApp) =>     {         configApp.AddJsonFile("appsettings.json", true);         configApp.AddJsonFile($"appsettings.{hostContext.HostingEnvironment.EnvironmentName}.json", true);         configApp.AddEnvironmentVariables();         //configApp.AddCommandLine(args);     })     .ConfigureServices((hostContext, services) =>     {         services.AddLogging();         services.AddHostedService<TimedHostedService>();     })     .ConfigureLogging((hostContext, configLogging) =>     {         configLogging.AddConsole();         if (hostContext.HostingEnvironment.EnvironmentName == EnvironmentName.Development)         {             configLogging.AddDebug();         }     })     .UseConsoleLifetime()     .Build();  host.Run();

5. 查看结果

6. 代码解析

a. Host配置

.ConfigureHostConfiguration(configHost =>

{

　　//配置根目录

　　//读取host的配置json，和appsetting类似，暂不需要先注释掉，可根据需要开启

　　//读取环境变量，Asp.Net core默认的环境变量是以ASPNETCORE_作为前缀的，这里也采用此前缀以保持一致

　　//可以在启动host的时候之前可传入参数，暂不需要先注释掉，可根据需要开启

　　//configHost.AddCommandLine(args);

})

b. App配置

.ConfigureAppConfiguration((hostContext, configApp) =>

{

　　//读取应用的配置json

　　//读取应用特定环境下的配置json

　　//读取环境变量

　　//可以在启动host的时候之前可传入参数，暂不需要先注释掉，可根据需要开启

　　//configApp.AddCommandLine(args);

})

c. 配置服务及依赖注入注册，注：没有Middleware的配置了。

.ConfigureServices((hostContext, services) =>
{

　　//添加日志Service
　　services.AddLogging();

　　//添加Timer Hosted Service
　　services.AddHostedService<TimedHostedService>();
})

.ConfigureLogging((hostContext, configLogging) =>
{

　　//输出控制台日志
　　configLogging.AddConsole();

　　//开发环境输出Debug日志
　　if (hostContext.HostingEnvironment.EnvironmentName == EnvironmentName.Development)
　　{
　　　　configLogging.AddDebug();
　　}
})

e. 使用控制台生命周期

.UseConsoleLifetime() //使用Ctrl + C退出

其它详细的可参考：https://docs.microsoft.com/en-us/aspnet/core/fundamentals/host/generic-host?view=aspnetcore-2.1

使用Quartz

1. 添加Host Nuget包。

Install-Package Quartz -Version 3.0.5 Install-Package Quartz.Plugins -Version 3.0.5

2. Quartz配置。

之前Quartz的配置是放在quartz.config里面的，但我更喜欢使用appsettings.json，因此，把配置改成了从appsettings.json。

先建一个QuartzOption的类：

/// <summary> /// 更多设置请参考：https://github.com/quartznet/quartznet/blob/master/src/Quartz/Impl/StdSchedulerFactory.cs /// </summary> public class QuartzOption {     public QuartzOption(IConfiguration config)     {         if (config == null)         {             throw new ArgumentNullException(nameof(config));         }          var section = config.GetSection("quartz");         section.Bind(this);     }      public Scheduler Scheduler { get; set; }      public ThreadPool ThreadPool { get; set; }      public Plugin Plugin { get; set; }      public NameValueCollection ToProperties()     {         var properties = new NameValueCollection         {             ["quartz.scheduler.instanceName"] = Scheduler?.InstanceName,             ["quartz.threadPool.type"] = ThreadPool?.Type,             ["quartz.threadPool.threadPriority"] = ThreadPool?.ThreadPriority,             ["quartz.threadPool.threadCount"] = ThreadPool?.ThreadCount.ToString(),             ["quartz.plugin.jobInitializer.type"] = Plugin?.JobInitializer?.Type,             ["quartz.plugin.jobInitializer.fileNames"] = Plugin?.JobInitializer?.FileNames         };          return properties;     } }  public class Scheduler {     public string InstanceName { get; set; } }  public class ThreadPool {     public string Type { get; set; }      public string ThreadPriority { get; set; }      public int ThreadCount { get; set; } }  public class Plugin {     public JobInitializer JobInitializer { get; set; } }  public class JobInitializer {     public string Type { get; set; }     public string FileNames { get; set; } }

3. 重写JobFactory。

public class JobFactory : IJobFactory {     private readonly IServiceProvider _serviceProvider;      public JobFactory(IServiceProvider serviceProvider)     {         _serviceProvider = serviceProvider;     }      public IJob NewJob(TriggerFiredBundle bundle, IScheduler scheduler)     {         var job = _serviceProvider.GetService(bundle.JobDetail.JobType) as IJob;         return job;     }      public void ReturnJob(IJob job)     {     } }

4. 编写Quartz Hosted Service

public class QuartzService : IHostedService {     private readonly ILogger _logger;     private readonly IScheduler _scheduler;      public QuartzService(ILogger<QuartzService> logger, IScheduler scheduler)     {         _logger = logger;         _scheduler = scheduler;     }      public async Task StartAsync(CancellationToken cancellationToken)     {         _logger.LogInformation("开始Quartz调度...");         await _scheduler.Start(cancellationToken);     }      public async Task StopAsync(CancellationToken cancellationToken)     {         _logger.LogInformation("停止Quartz调度...");         await _scheduler.Shutdown(cancellationToken);     } }

5. 准备appsettings.json

{   "quartz": {     "scheduler": {       "instanceName": "HostedService.Quartz"     },     "threadPool": {       "type": "Quartz.Simpl.SimpleThreadPool, Quartz",       "threadPriority": "Normal",       "threadCount": 10     },     "plugin": {       "jobInitializer": {         "type": "Quartz.Plugin.Xml.XMLSchedulingDataProcessorPlugin, Quartz.Plugins",         "fileNames": "quartz_jobs.xml"       }     }   } }

6. 编写一个TestJob

public class TestJob : IJob {     private readonly ILogger _logger;      public TestJob(ILogger<TestJob> logger)     {         _logger = logger;     }      public Task Execute(IJobExecutionContext context)     {         _logger.LogInformation(string.Format("[{0:yyyy-MM-dd hh:mm:ss:ffffff}]任务执行！", DateTime.Now));         return Task.CompletedTask;     } }

7. 准备Quartz的调度文件quartz_jobs.xml

<?xml version="1.0" encoding="UTF-8"?>  <job-scheduling-data xmlns="http://quartznet.sourceforge.net/JobSchedulingData"         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"                  version="2.0">    <processing-directives>     <overwrite-existing-data>true</overwrite-existing-data>   </processing-directives>    <schedule>     <job>       <name>TestJob</name>       <group>TestGroup</group>       <description>测试任务</description>       <job-type>HostedService.Quartz.Jobs.TestJob, HostedService.Quartz</job-type>       <durable>true</durable>       <recover>false</recover>     </job>     <trigger>       <simple>         <name>TestTrigger</name>         <group>TestGroup</group>         <description>测试触发器</description>         <job-name>TestJob</job-name>         <job-group>TestGroup</job-group>         <repeat-count>-1</repeat-count>         <repeat-interval>2000</repeat-interval>       </simple>     </trigger>      <!--<trigger>       <cron>         <name>TestTrigger</name>         <group>TestGroup</group>         <description>测试触发器</description>         <job-name>TestJob</job-name>         <job-group>TestGroup</job-group>         <cron-expression>0/2 * * * * ?</cron-expression>       </cron>     </trigger>-->   </schedule> </job-scheduling-data>

8. 注册Quartz Hosted Service和TestJob

.ConfigureServices((hostContext, services) => {     services.AddLogging();     //services.AddHostedService<TimedHostedService>();      services.AddSingleton<IJobFactory, JobFactory>();     services.AddSingleton(provider =>     {         var option = new QuartzOption(hostContext.Configuration);         var sf = new StdSchedulerFactory(option.ToProperties());         var scheduler = sf.GetScheduler().Result;         scheduler.JobFactory = provider.GetService<IJobFactory>();         return scheduler;     });     services.AddHostedService<QuartzService>();      services.AddSingleton<TestJob, TestJob>(); })