目录
简介
基本用法
进阶使用
集成第三方日志 Nlog
集成 EF Core
消费 MQ 消息
集成 Quartz
部署
BackgroundService 和 IHostedService
源代码
参考
简介
我们在做项目的时候, 往往要处理一些后台的任务. 一般是两种, 一种是不停的运行，比如消息队列的消费者。另一种是定时任务。
在.NET Framework + Windows环境里, 我们一般会使用 Windows 服务处理这些情形.
但在.Net Core + Linux环境里, 有没有类似的解决方案呢? 了解的方法有两种:
Web Host: 创建一个 ASP.Net Core 的 Web 项目(如MVC 或 WebAPI), 然后使用IHostedService或者BackgroundService处理后台任务. 这种方案是Web项目和后台任务混杂在一起运行.
Generic Host: 通用主机是 .NET Core 2.1 中的新增功能, 它将HTTP管道从Web Host的API中分离出来, 从而提供更多的主机选择方案, 比如后台任务, 非 HTTP 工作负载等. 同时可以方便使用基础功能如配置、依赖关系注入 [DI] 和日志记录等。
Web Host and Host
基本用法
创建一个控制台程序并添加Hosting Nuget包。
Install-Package Microsoft.Extensions.Hosting
Install-Package Microsoft.Extensions.Configuration.EnvironmentVariables
Install-Package Microsoft.Extensions.Configuration.CommandLine
Install-Package Microsoft.Extensions.Configuration.Json
Install-Package Microsoft.Extensions.Logging.Console
Install-Package Microsoft.Extensions.Logging.Debug
创建一个基于 Timer 的简单 Hosted Service. 继承自抽象类 BackgroundService.
public class TimedHostedService : BackgroundService
{
private readonly ILogger _logger;
private Timer _timer;
public TimedHostedService(ILogger
logger)
{
this._logger = logger;
}
protected override Task ExecuteAsync(CancellationToken stoppingToken)
{
_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 override Task StopAsync(CancellationToken cancellationToken)
{
_logger.LogInformation("Timed Background Service is stopping.");
_timer?.Change(Timeout.Infinite, 0);
return Task.CompletedTask;
}
public override void Dispose()
{
_timer?.Dispose();
base.Dispose();
}
}
Main 函数中添加 Host的相关代码.
static async Task Main(string[] args)
{
var builder = new HostBuilder()
//Host config
.ConfigureHostConfiguration(configHost =>
{
//配置根目录
//configHost.SetBasePath(Directory.GetCurrentDirectory());
//读取host的配置json，和appsetting类似
//configHost.AddJsonFile("hostsettings.json", true, true);
//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
configHost.AddEnvironmentVariables(prefix: "ASPNETCORE_");
//启动host的时候之可传入参数
if (args != null)
{
configHost.AddCommandLine(args);
}
})
//App config
.ConfigureAppConfiguration((hostContext, configApp) =>
{
//读取应用的配置json
configApp.AddJsonFile("appsettings.json", optional: true);
//读取应用特定环境下的配置json
configApp.AddJsonFile($"appsettings.{hostContext.HostingEnvironment.EnvironmentName}.json", optional: true);
//读取环境变量
configApp.AddEnvironmentVariables();
//启动host的时候可传入参数
if (args != null)
{
configApp.AddCommandLine(args);
}
})
//配置服务及依赖注入注册
.ConfigureServices((hostContext, services) =>
{
//添加TimedHostedService
services.AddHostedService();
})
//日志配置
.ConfigureLogging((hostContext, configLogging) =>
{
//输出控制台日志
configLogging.AddConsole();
//输出Debug日志
if (hostContext.HostingEnvironment.EnvironmentName == EnvironmentName.Development)
{
configLogging.AddDebug();
}
});
//使用控制台生命周期, Ctrl + C退出
await builder.RunConsoleAsync();
}
运行并测试.
进阶使用
集成第三方日志 Nlog
支持.Net Core的第三方日志库有很多, 下面以 Nlog 为例, 集成到 Generic host 里.
添加 NLog.Extensions.Hosting Nuget包
Install-Package NLog.Extensions.Hosting
添加配置文件
新建一个文件nlog.config(建议全部小写，linux系统中要注意)， 并右键点击其属性，将其“复制到输出目录”设置为“始终复制”。文件内容如下:
Always
修改 Main 方法:
static async Task Main(string[] args)
{
var logger = LogManager.GetCurrentClassLogger();
try
{
var builder = new HostBuilder()
//Host config
.ConfigureHostConfiguration(configHost =>
{
})
//App config
.ConfigureAppConfiguration((hostContext, configApp) =>
{
})
//Services
.ConfigureServices((hostContext, services) =>
{
})
//Log
//.ConfigureLogging((hostContext, configLogging) =>
//{
// configLogging.AddConsole();
// if (hostContext.HostingEnvironment.EnvironmentName == EnvironmentName.Development)
// {
// configLogging.AddDebug();
// }
//})
.UseNLog();
await builder.RunConsoleAsync();
}
catch (Exception ex)
{
logger.Fatal(ex, "Stopped program because of exception");
throw;
}
finally
{
// Ensure to flush and stop internal timers/threads before application-exit (Avoid segmentation fault on Linux)
LogManager.Shutdown();
}
}
运行并测试.
集成 EF Core
EF Core的集成相对比较简单, 基本上和我们在 MVC / WebAPI 中用法一样.
添加 Nuget 包
// SQL Server
Install-Package Microsoft.EntityFrameworkCore.SqlServer
添加实体
public class Product
{
public int Id { get; set; }
public string Name { get; set; }
public int Count { get; set; }
}
public class ProductConfiguration : IEntityTypeConfiguration
{
public void Configure(EntityTypeBuilder builder)
{
builder.Property(t => t.Name).IsRequired().HasMaxLength(100);
builder.HasData(new Product { Id = 1, Name = "Test_Prouct_1", Count = 0 });
}
}
添加数据库上下文
public class HostDemoContext : DbContext
{
public HostDemoContext(DbContextOptions options) : base(options)
{ }
public DbSet Products { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.ApplyConfiguration(new ProductConfiguration());
}
}
添加数据库连接字符串到 appsettings.json 并修改 Main 方法
{
"sqlserverconnection": "Server=.\\SQLEXPRESS;Database=GenericHostDemo;Trusted_Connection=True;"
}
//Services
.ConfigureServices((hostContext, services) =>
{
var connectionString = hostContext.Configuration["sqlserverconnection"];
services.AddDbContext(o => o.UseSqlServer(connectionString), ServiceLifetime.Singleton);
services.AddHostedService();
})
在 Hosted Service 中使用 Context
private readonly HostDemoContext _context;
public TimedHostedService(HostDemoContext context)
{
this._context = context;
}
private void DoWork(object state)
{
int id = 1;
var product = _context.Products.Find(id);
product.Count++;
_context.SaveChanges();
_logger.LogInformation($"Processed {product.Name} at {DateTime.Now:yyyy-MM-dd hh:mm:ss}, current count is {product.Count}.");
//_logger.LogInformation(string.Format("[{0:yyyy-MM-dd hh:mm:ss}] Timed Background Service is working.", DateTime.Now));
}
迁移Migration
通过 Nuget 添加引用 Install-Package Microsoft.EntityFrameworkCore.Tools
创建 DesignTimeDbContextFactory 类
不同于Web项目, 执行Add-Migration迁移命令时候由于拿不到连接字符串可能会报错 Unable to create an object of type 'HostDemoContext'. Add an implementation of 'IDesignTimeDbContextFactory' to the project, or see https://go.microsoft.com/fwlink/?linkid=851728 for additional patterns supported at design time.
解决方法：创建一个与DbContext同一目录下的DesignTimeDbContextFactory文件，然后实现接口中的方法CreateDbContext，并配置ConnectionString:
public class DesignTimeDbContextFactory : IDesignTimeDbContextFactory
{
public HostDemoContext CreateDbContext(string[] args)
{
var builder = new DbContextOptionsBuilder();
builder.UseSqlServer("Server=.\\SQLEXPRESS;Database=GenericHostDemo;Trusted_Connection=True;");
return new HostDemoContext(builder.Options);
}
}
生成迁移. 打开Package Manager Console，执行命令 Add-Migration InitialCreate
更新迁移到数据库. 执行命令 Update-Database。
运行并测试.
消费 MQ 消息
接下来实现一个后台任务用于监听并消费 RabbitMQ 消息.
这里使用库EasyNetQ, 它是一款基于RabbitMQ.Client封装的API库，正如其名，使用起来比较Easy，它把原RabbitMQ.Client中的很多操作都进行了再次封装，让开发人员减少了很多工作量。详细请参考 https://github.com/EasyNetQ/EasyNetQ
添加 EasyNetQ 相关 Nuget 包
install-package EasyNetQ
install-package EasyNetQ.DI.Microsoft
创建后台服务 RabbitMQDemoHostedService
public class RabbitMQDemoHostedService : BackgroundService
{
private readonly ILogger _logger;
private readonly IBus _bus;
public RabbitMQDemoHostedService(ILogger logger, IBus bus)
{
this._logger = logger;
this._bus = bus;
}
protected override Task ExecuteAsync(CancellationToken stoppingToken)
{
_bus.Subscribe("demo_subscription_1", HandleDemoMessage);
return Task.CompletedTask;
}
private void HandleDemoMessage(DemoMessage demoMessage)
{
_logger.LogInformation($"Got Message : {demoMessage.Id} {demoMessage.Text} {demoMessage.CreatedTime}");
}
}
Program 里面配置相关服务
//Services
.ConfigureServices((hostContext, services) =>
{
//Rabbit MQ
string rabbitMqConnection = hostContext.Configuration["rabbitmqconnection"];
services.RegisterEasyNetQ(rabbitMqConnection);
services.AddHostedService();
})
启动 MQ 发送程序来模拟消息的发送并测试.
集成 Quartz
Quartz 是一个开源作业调度框架, quartznet的详细信息请参考 http://www.quartz-scheduler.net/ , 集成 Quartz 可以帮助提供比只使用定时器更强大的功能.
添加 Quartz 相关 Nuget 包
Install-Package Quartz
Install-Package Quartz.Plugins
新建 Quartz 配置类 QuartzOption
// More settings refer to：https://github.com/quartznet/quartznet/blob/master/src/Quartz/Impl/StdSchedulerFactory.cs
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; }
}
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)
{
var disposable = job as IDisposable;
disposable?.Dispose();
}
}
编写 Quartz Hosted Service
public class QuartzService : BackgroundService
{
private readonly ILogger _logger;
private readonly IScheduler _scheduler;
public QuartzService(ILogger logger, IScheduler scheduler)
{
_logger = logger;
_scheduler = scheduler;
}
protected override async Task ExecuteAsync(CancellationToken stoppingToken)
{
_logger.LogInformation("Start quartz scheduler...");
await _scheduler.Start(stoppingToken);
}
public override async Task StopAsync(CancellationToken cancellationToken)
{
_logger.LogIn
