.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>();
//builder.RegisterWebApiModelBinderProvider();
// Create the Autofac container
var container = builder.Build();
_containerProvider = new ContainerProvider(container);
//config.DependencyResolver = new AutofacWebApiDependencyResolver(container);
// Get a logger from container
//var logger = container.Resolve<ILogger<WebApiApplication>>();
//logger.LogInformation("Finished container build, starting background services");
// Start the Discovery client background thread
container.StartDiscoveryClient();
//logger.LogInformation("Finished starting background services");
}
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();
}
}
