（十二）Bind读取配置到C#实例

• 继续上一节的，接下来用Options或者Bind把json文件里的配置转成C#的实体，相互之间映射起来。首先新建一个asp.net core mvc项目OptionsBindSample
• Startup.cs，这里用依赖注入把Configuration加进来

•          public IConfiguration Configuration { get; set; }
  
           public Startup(IConfiguration configuration)
           {
               this.Configuration = configuration;
           }

• 再建立一个Class.cs

•  public class Class
           {
               public int ClassNo { get; set; }
               public string ClassDesc { get; set; }
               public List<Student> Students { get; set; }
           }
  
           public class Student
           {
               public string Name { get; set; }
               public string Age { get; set; }
           }

• 再建一个appsettings.json(名称一定要叫这个，因为在Program.cs中WebHost.CreateDefaultBuilder(args)会默认读取appsettings.json文件)

•  {
     "ClassNo": "",
     "ClassDesc": "ASP.NET Core 101",
     "Students": [
       {
         "name": "liuxh",
         "age": ""
       },
       {
         "name": "linhj",
         "age": ""
       },
       {
         "name": "liuxy",
         "age": ""
  
       },
       {
         "name": "liuss",
         "age": ""
       }
     ]
  
   }

• 最后Starup.cs代码是这样的

•         public IConfiguration Configuration { get; set; }
  
          public Startup(IConfiguration configuration)
          {
              this.Configuration = configuration;
          }
  
          // This method gets called by the runtime. Use this method to add services to the container.
          // For more information on how to configure your application, visit https://go.microsoft.com/fwlink/?LinkID=398940
          public void ConfigureServices(IServiceCollection services)
          {
  
          }
  
          // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
          public void Configure(IApplicationBuilder app, IHostingEnvironment env)
          {
              if (env.IsDevelopment())
              {
                  app.UseDeveloperExceptionPage();
              }
  
              app.Run(async (context) =>
              {
                  var myClass = new Class();
                  Configuration.Bind(myClass);//把配置文件的信息和对象映射起来
  
                  await context.Response.WriteAsync($"ClassNo:{myClass.ClassNo}");
                  await context.Response.WriteAsync($"ClassDesc:{myClass.ClassDesc}");
                  await context.Response.WriteAsync($"{myClass.Students.Count} Students");
  
              });
          }

• 最后启动网站