开始之前,如果没接触过Autofac的,可以移步到Autofac官方示例学习一下怎么使用:https://github.com/autofac/Examples
.net 下集成steeltoe进行微服务客户端的注册与发现均需要使用Autofac依赖注入方式进行,且MVC,WebAPI,webForm三种项目类型所需要依赖扩展库都不一样,经过两周的踩坑,现在做个粗浅的总结吧!
以下是steeltoe官方文档给出的参考:
App Type | Package | Description |
---|---|---|
Console/ASP.NET 4.x | Steeltoe.Discovery.EurekaBase |
Base functionality. No dependency injection. |
ASP.NET Core | Steeltoe.Discovery.ClientCore |
Includes base. Adds ASP.NET Core dependency injection. |
ASP.NET 4.x with Autofac | Steeltoe.Discovery.ClientAutofac |
Includes base. Adds Autofac dependency injection. |
App Type | Package | Description |
---|---|---|
Console/ASP.NET 4.x | Pivotal.Discovery.EurekaBase |
Base functionality. No dependency injection. |
ASP.NET Core | Pivotal.Discovery.ClientCore |
Includes base. Adds ASP.NET Core dependency injection. |
ASP.NET 4.x with Autofac | Pivotal.Discovery.ClientAutofac |
Includes base. Adds Autofac dependency injection. |
经过两周的各自尝试,基于Framework4.5.2+的MVC,WebAPI,webForm等项目基本都是用Autofac方式进行服务注册和调用方法的引用,所以所需要引入的扩展库基本都是以Autofac结尾,比如上面的Steeltoe.Discovery.ClientAutofac和Pivotal.Discovery.ClientAutofac。
另外我们还需要用到的类库包括:
Steeltoe.Common.Autofac
这个类库包含了服务发现与调用的方法。
三种类型的项目目录结构是不同的,MVC与WebAPI都是有ApiController接口的,可以自己构建controller集成接口,然后直接用Autofac的依赖注入方式进行微服务调用方法的实现,代码可参考如下:
public class ValuesController : ApiController
{
private readonly DiscoveryHttpClientHandler _handler; public ValuesController(IDiscoveryClient client, ILoggerFactory logFactory)//这里就是注入依赖了
{
_handler = new DiscoveryHttpClientHandler(client);
} // GET api/values
public async Task<string> Get()
{ var client = new HttpClient(_handler, false); return await client.GetStringAsync("http://java-server/hi?name=demo");
} // GET api/values/5
public string Get(int id)
{
String re = id.ToString; return re; } // POST api/values
public void Post([FromBody]string value)
{
} // PUT api/values/5
public void Put(int id, [FromBody]string value)
{
} // DELETE api/values/5
public void Delete(int id)
{
}
}
那么webForm怎么调用微服务的方法呢?这就需要我们自己写一个服务类,在类中实现自定义接口和用依赖注入的方式对steeltoe提供的方法调用,然后在Page里依赖注入自己的这个类了。参考代码:
自定义服务接口类IFetchService.cs:
public interface IFetchService
{
Task<string> RandomFortuneAsync();
}
自定义服务类并完成steeltoe接口方法的依赖注入与实现FetchService.cs:
public class FetchService : IFetchService
{
DiscoveryHttpClientHandler _handler; private const string RANDOM_FORTUNE_URL = "http://java-service/hi?name=tian";
private ILogger<FetchService> _logger; public FetchService(IDiscoveryClient client, ILoggerFactory logFactory = null)
{
_handler = new DiscoveryHttpClientHandler(client);
_logger = logFactory?.CreateLogger<FetchServise>();
} public async Task<string> RandomFortuneAsync()
{
_logger?.LogInformation("RandomFortuneAsync");
var client = GetClient();
return await client.GetStringAsync(RANDOM_FORTUNE_URL); } private HttpClient GetClient()
{
var client = new HttpClient(_handler, false);
return client;
}
}
接下来,最重要的步骤,在程序全局文件Global.asax中进行依赖注入的配置,这里引用到的Autofac扩展库也是有区别:
MVC直接引用Autofac即可
WebAPI引用的是Autofac.WebApi2
webForm引用的是Autofac.Web
这里主要写下 webForm的配置代码:
public class Global : System.Web.HttpApplication, IContainerProviderAccessor
{
// 持有应用程序容器的提供程序
static IContainerProvider _containerProvider; //将被`Autofac HttpModules`用来解析和注入依赖关系的实例属性。
public IContainerProvider ContainerProvider
{
get { return _containerProvider; }
} protected void Application_Start(object sender, EventArgs e)
{
ApplicationConfig.RegisterConfig("development");
//var config = GlobalConfiguration.Configuration;
var builder = new ContainerBuilder(); // Add Microsoft Options to container
builder.RegisterOptions(); // Add Microsoft Logging to container
builder.RegisterLogging(ApplicationConfig.Configuration); // Add Console logger to container
builder.RegisterConsoleLogging(); //// Register all the controllers with Autofac
builder.RegisterAssemblyModules(Assembly.GetExecutingAssembly()); // Register IDiscoveryClient, etc.
builder.RegisterDiscoveryClient(ApplicationConfig.Configuration); // Register FortuneService builder.RegisterType<FetchServise>().As<IFetchServise>();//MVC,webAPI也是这么写 // Create the Autofac container
var container = builder.Build(); _containerProvider = new ContainerProvider(container); //config.DependencyResolver = new AutofacWebApiDependencyResolver(container);//WebAPI创建容器
//DependencyResolver.SetResolver(new AutofacDependencyResolver(container));//MVC创建容器 container.StartDiscoveryClient(); } protected void Session_Start(object sender, EventArgs e)
{ } protected void Application_BeginRequest(object sender, EventArgs e)
{ } protected void Application_AuthenticateRequest(object sender, EventArgs e)
{ } protected void Application_Error(object sender, EventArgs e)
{ } protected void Session_End(object sender, EventArgs e)
{ } protected void Application_End(object sender, EventArgs e)
{ }
}
然后在Page代码页中依赖注入实现我们自定义的接口方法:
public partial class WebForm2 : System.Web.UI.Page
{
public IFetchServise fetch { get; set; }
protected void Page_Load(object sender, EventArgs e)
{
this.Page.RegisterAsyncTask(new PageAsyncTask(GetName));
} private async Task GetName()
{
Label1.Text = await fetch.RandomFortuneAsync();
}
}