OptionsSnapshot 读取配置

使用DI读取配置，读取时声明类型有IOptions<T>、IOptionsMonitor<T>、IOtionsSnapshot<T>类型，推荐使用最后一种。

要读取的配置文件 jsconfig.json 如下，把属性改成始终复制。

{
  "Name": "wzh",
  "addr": "beijing",
  "Teacher": {
    "Name": "zhangsan",
    "Age": 45
  }
}

using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;
using System;
using System.Linq;

namespace ConsoleApp8
{
    class Program
    {
        static void Main(string[] args)
        {

            IServiceCollection service = new ServiceCollection();
            service.AddScoped<Demo1>();
            service.AddScoped<Demo2>();

            ConfigurationBuilder configbuilder = new ConfigurationBuilder();
            configbuilder.AddJsonFile("jsconfig.json", optional: false, reloadOnChange: false);
            var root = configbuilder.Build();
            service.AddOptions()
                .Configure<Student>(x => root.Bind(x))
                .Configure<Teacher>(x=>root.GetSection("Teacher").Bind(x));


            using (var sp=service.BuildServiceProvider())
            {
                var demo1=sp.GetRequiredService<Demo1>();
                var demo2= sp.GetRequiredService<Demo2>();

                demo1.Test();
                demo2.Test();
            }

                Console.WriteLine("Hello World!");
        }
    }
    public class Demo1
    {
        private readonly IOptionsSnapshot<Student> config;
        public Demo1(IOptionsSnapshot<Student> config)
        {
            this.config = config;
        }
        public void Test()
        {
            Console.WriteLine("学生");
            Console.WriteLine(config.Value.Name);
            Console.WriteLine(config.Value.Addr);
        }
    }
    public class Demo2
    {
        private readonly IOptionsSnapshot<Teacher> config;
        public Demo2(IOptionsSnapshot<Teacher> config)
        {
            this.config = config;
        }
        public void Test()
        {
            Console.WriteLine("老师");
            Console.WriteLine(config.Value.Name);
            Console.WriteLine(config.Value.Age);
        }
    }
    public class Student
    {
        public string Name { get; set; }
        public string Addr { get; set; }

    }
    public class Teacher
    {
        public string Name { get; set; }
        public int Age { get; set; }
    }
}