{
 //Routes:处理上游请求的对象(客户端)，每个数组{}就是配置：上游地址和对应下游地址
 "Routes": [
 {
  //以Downstream开头的，是要转发到下游服务器的地址(CustomersAPIServices)，与nginx转发类似
  //下面所有Downstream开头的，组成一个转发url,转发地址是http://localhost:9001/api/customers
  "DownstreamPathTemplate": "/api/customers",
  "DownstreamScheme": "http",
  // "DownstreamHost": "localhost",
  // "DownstreamPort": 9001,
  //转发到下游服务器的主机和端口。
  "DownstreamHostAndPorts": [
  {
   "Host": "localhost",
   "Port": 9001
  }
  ],
  //Upstream开头是指上游服务器（客户端）访问地址，通过http get方式访问。
  //也就是说客户端访问http://localhost:9000/customers 实际是转发到了http://localhost:9001/api/customers的服务
  "UpstreamPathTemplate": "/customers",
  "UpstreamHttpMethod": [ "Get" ]
 },
 {
  "DownstreamPathTemplate": "/api/customers/{id}",
  "DownstreamScheme": "http",
  // "DownstreamHost": "localhost",
  // "DownstreamPort": 9001,
  "DownstreamHostAndPorts": [
  {
   "Host": "localhost",
   "Port": 9001
  }
  ],
  "UpstreamPathTemplate": "/customers/{id}",
  "UpstreamHttpMethod": [ "Get" ]
 },
 {
  "DownstreamPathTemplate": "/api/products",
  "DownstreamScheme": "http",
  // "DownstreamPort": 9002,
  // "DownstreamHost": "localhost",
  "DownstreamHostAndPorts": [
  {
   "Host": "localhost",
   "Port": 9002
  }
  ],
  "UpstreamPathTemplate": "/products",
  "UpstreamHttpMethod": [ "Get" ]
 }
 ],
 //全局配置,允许覆盖Routes特定设置
 "GlobalConfiguration": {
 "RequestIdKey": "OcRequestId",
 "AdministrationPath": "/administration"
 }
}

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
   WebHost.CreateDefaultBuilder(args)
    //.UseStartup<Startup>()
    //设置网关url
    .UseUrls("http://*:9000")
    .ConfigureAppConfiguration((hostingContext, config) =>
    {
     //添加Ocelot配置文件
config.SetBasePath(hostingContext.HostingEnvironment.ContentRootPath)
       .AddJsonFile("configuration.json")
       .AddEnvironmentVariables();
    })
    .ConfigureServices(s =>
    {
     //添加Ocelot服务
     s.AddOcelot();
    })
    .Configure(a =>
    {
     //使用Ocelot中间件
     a.UseOcelot().Wait();
    });

[Route("api/[controller]")]
public class CustomersController : Controller
{  
 [HttpGet]
 public IEnumerable<string> Get()
 {
  return new string[] { "Catcher Wong", "James Li" };
 }

 [HttpGet("{id}")]
 public string Get(int id)
 {
  return $"Catcher Wong - {id}";
 }   
}

[Route("api/[controller]")]
public class ProductsController : Controller
{
 [HttpGet]
 public IEnumerable<string> Get()
 {
  return new string[] { "Surface Book 2", "Mac Book Pro" };
 }
}