首先，寫一個簡單的可被呼叫的服務註冊到服務中心，我們這命名為java-service,用的是IDEA建立一個spring boot專案，選擇spring client型別。 修改application.properties，配置服務中心地址和服務埠號：

spring.application.name=java-service
​
server.port=3222
​
eureka.client.serviceUrl.defaultZone=http://localhost:8761/eureka/

修改pom.xml，加入架包引用：

  <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
​
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
​
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-eureka</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

修改主程式入口DemoclientApplication.java:

package com.ty.democlient;
​
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
​
@SpringBootApplication
@EnableEurekaClient
@RestController
public class DemoclientApplication {
​
    public static void main(String[] args) {
        SpringApplication.run(DemoclientApplication.class, args);
    }
​
    @Value("${server.port}")
    String port;
    @RequestMapping("/hi")
    public String home(@RequestParam String name) {
        return "hi "+name+",i am from port:" +port;
    }
}

把服務跑起來之後，我們看到在服務中心已經能看見這個服務了： 現在我們的目標是在另外一個.NET MVC專案裡通過服務名就能正常呼叫到這個服務，來看看怎麼做： 新建一個基於.Net Framework 4.5 的MVC專案，首先根目錄還是要有一個appsettings.json的檔案作為服務配置檔案：

{
  "spring": {
    "application": {
      "name": "demo_netfetch"
    }
  },
  "eureka": {
    "client": {
      "serviceUrl
 
": "http://localhost:8761/eureka/",
      "shouldFetchRegistry": true,
      "shouldRegisterWithEureka": true,
      "validate_certificates": false
    },
    "instance": {
      "port": 3001
      // Remove comments to enable SSL requests
      // More changes in Program.cs are required if using direct C2C communications
      //,"securePortEnabled": true
    }
  },
  "Logging": {
    "IncludeScopes": false,
    "LogLevel": {
      "Default": "Debug",
      "Pivotal": "Debug",
      "Steeltoe": "Debug"
    }
  }
}

​

shouldFetchRegistry設定為true代表這是一個服務發現客戶端 然後在專案目錄下建立Service呼叫的類，配置具體呼叫的服務名，內容輸出方式等：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Net.Http;
using System.Threading.Tasks;
using System.Web;
using Microsoft.Extensions.Logging;
using Steeltoe.Common.Discovery;
​
namespace DemoNetFetchClient.Services
{
    public class FetchServise : IFetchServise
    {
        DiscoveryHttpClientHandler _handler;
​
        private const string RANDOM_FORTUNE_URL = "http://java-service/hi?name=tian";//服務中心已註冊的服務地址
        private ILogger<FetchServise> _logger;
​
        public FetchServise(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;
        }
    }
}

注意這裡需要引用擴充套件包：Steeltoe.Common.Discovery，從NuGet里加載就可以，注意版本，要選擇NET專用的，而不是Core用的。 修改HomeController.cs,非同步請求呼叫內部服務：

public class HomeController : Controller
    {
        IFetchServise _fortunes;
        ILogger<HomeController> _logger;
​
        public HomeController(IFetchServise fortunes,  ILoggerFactory logFactory = null)
        {
            _fortunes = fortunes;
            _logger = logFactory?.CreateLogger<HomeController>();
        }
​
        public async System.Threading.Tasks.Task<ActionResult> Index()
        {
            ViewBag.Message = await _fortunes.RandomFortuneAsync();
​
            return View();
        }
​
       
    }

修改Global.asax，註冊服務客戶端:
 這裡要注意，如果專案是webapi程式，需要按Autofac整合webAPI的配置，具體請參考我的另一篇筆記：C# Autofac整合之Framework WebAPI

protected void Application_Start()
        {
​
            AreaRegistration.RegisterAllAreas();
            FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
            RouteConfig.RegisterRoutes(RouteTable.Routes);
            BundleConfig.RegisterBundles(BundleTable.Bundles);
​
            ApplicationConfig.RegisterConfig("development");
​
            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.RegisterControllers(typeof(MvcApplication).Assembly);
​
            // Register IDiscoveryClient, etc.
            builder.RegisterDiscoveryClient(ApplicationConfig.Configuration);
​
            // Register FortuneService
            builder.RegisterType<FetchServise>().As<IFetchServise>().SingleInstance();
​
            // Create the Autofac container
            var container = builder.Build();
            DependencyResolver.SetResolver(new AutofacDependencyResolver(container));
​
            // Get a logger from container
            var logger = container.Resolve<ILogger<MvcApplication>>();
​
            logger.LogInformation("Finished container build, starting background services");
​
            // Start the Discovery client background thread
 
 
            container.StartDiscoveryClient();
​
            logger.LogInformation("Finished starting background services");
        }

ok!done!程式跑起來效果，成功呼叫到服務中心內部服務java-service：