ASP.NET Core快速入门（Jessetalk）（第2章：配置管理）

课程链接：http://video.jessetalk.cn/course/explore

良心课程，大家一起来学习哈！

任务9：配置介绍

• 命令行配置
• Json文件配置
• 从配置文件文本到c#对象实例的映射 - Options 与 Bind
• 配置文件热更新
• 框架设计：Configuration

任务10：命令行配置

新建一个项目CommandLineSample--控制台应用（.NET Core）

依赖性右键--管理NuGet程序包--下载microsoft.aspnetcore.all

传入参数

using System;using Microsoft.Extensions.Configuration;namespace CommandLineSample{ ???class Program ???{ ???????static void Main(string[] args) ???????{ ???????????var builder = new ConfigurationBuilder() ???????????????.AddCommandLine(args); ???????????var configuration = builder.Build(); ???????????Console.WriteLine($"name: {configuration ["name"]}"); ???????????Console.WriteLine($"age: {configuration["age"]}"); ???????????Console.ReadLine(); ???????} ???}}

需要通过项目右键--调试--输入参数：name=mingsonzheng age=18

启动项目，得到结果：

默认参数

using System;using System.Collections.Generic;using Microsoft.Extensions.Configuration;namespace CommandLineSample{ ???class Program ???{ ???????static void Main(string[] args) ???????{ ???????????var settings = new Dictionary<string, string> ???????????{ ???????????????{"name", "mingsonzheng" }, ???????????????{"age", "18" } ???????????}; ???????????var builder = new ConfigurationBuilder() ???????????????.AddInMemoryCollection(settings) ???????????????.AddCommandLine(args); ???????????var configuration = builder.Build(); ???????????Console.WriteLine($"name: {configuration ["name"]}"); ???????????Console.WriteLine($"age: {configuration["age"]}"); ???????????Console.ReadLine(); ???????} ???}}

清空应用程序参数

启动项目

通过PowerShell运行程序，默认参数与传入参数

PS C:\WINDOWS\system32> d:PS D:\> cd D:\jessetalk\CommandLineSample\CommandLineSample\bin\Debug\netcoreapp2.1PS D:\jessetalk\CommandLineSample\CommandLineSample\bin\Debug\netcoreapp2.1> dir ???目录: D:\jessetalk\CommandLineSample\CommandLineSample\bin\Debug\netcoreapp2.1Mode ???????????????LastWriteTime ????????Length Name---- ???????????????------------- ????????------ -----a---- ??????2019-01-23 ????23:54 ????????244607 CommandLineSample.deps.json-a---- ??????2019-01-24 ?????0:01 ??????????5632 CommandLineSample.dll-a---- ??????2019-01-24 ?????0:01 ???????????604 CommandLineSample.pdb-a---- ??????2019-01-23 ????23:54 ???????????240 CommandLineSample.runtimeconfig.dev.json-a---- ??????2019-01-23 ????23:54 ???????????154 CommandLineSample.runtimeconfig.jsonPS D:\jessetalk\CommandLineSample\CommandLineSample\bin\Debug\netcoreapp2.1> dotnet CommandLineSample.dllname: mingsonzhengage: 18PS D:\jessetalk\CommandLineSample\CommandLineSample\bin\Debug\netcoreapp2.1> dotnet CommandLineSample.dll name=jim age=22name: jimage: 22

任务11：Json文件配置

新建一个项目JsonComfigSample--控制台应用（.NET Core）

依赖性右键--管理NuGet程序包--下载microsoft.aspnetcore.all

添加Json文件：项目右键--添加新建项class.json

{ ?"ClassNo": "1", ?"ClassDesc": "ASP.NET Core 101", ?"Students": [ ???{ ?????"name": "mingsonzheng", ?????"age": "18" ???}, ???{ ?????"name": "jim", ?????"age": "28" ???}, ???{ ?????"name": "tom", ?????"age": "38" ???} ?]}

由于class.json不在bin\Debug目录下，所以默认不会被编译，需要修改它的属性，文件右键属性

using System;using Microsoft.Extensions.Configuration;namespace JsonComfigSample{ ???class Program ???{ ???????static void Main(string[] args) ???????{ ???????????var builder = new ConfigurationBuilder() ???????????????.AddJsonFile("class.json"); ???????????Console.ReadLine(); ???????} ???}}

启动项目，可以看到class.json被复制到bin\Debug目录，这样dll就可以读取到class.json文件

读取json文件

using System;using Microsoft.Extensions.Configuration;namespace JsonComfigSample{ ???class Program ???{ ???????static void Main(string[] args) ???????{ ???????????var builder = new ConfigurationBuilder() ???????????????.AddJsonFile("class.json"); ???????????// 调用Build之前请确保拷贝的class.json文件没有格式错误 ???????????var configuration = builder.Build(); ???????????Console.WriteLine($"ClassNo: { configuration["ClassNo"]}"); ???????????Console.WriteLine($"ClassDesc: { configuration["ClassDesc"]}"); ???????????Console.WriteLine("Students"); ???????????Console.Write(configuration["Students:0:name"]); ???????????Console.WriteLine(configuration["Students:0:age"]); ???????????Console.Write(configuration["Students:1:name"]); ???????????Console.WriteLine(configuration["Students:1:age"]); ???????????Console.Write(configuration["Students:2:name"]); ???????????Console.WriteLine(configuration["Students:2:age"]); ???????????Console.ReadLine(); ???????} ???}}

启动项目

任务12：Bind读取配置到C#实例

新建一个ASP.NET Core Web 应用程序OptionsBindSample，直接选择 空，确定

在Startup.cs中通过依赖注入添加configuration

public IConfiguration Configuration { get; set; }public Startup(IConfiguration configuration){ ???Configuration = configuration;}

项目右键，新建项，添加一个类Class.cs

using System;using System.Collections.Generic;using System.Linq;using System.Threading.Tasks;namespace OptionsBindSample{ ???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; } ???}}

项目右键，新建项，添加一个Json文件appsettings.json

为什么取名appsettings.json呢？

因为Program.cs中的CreateDefaultBuilder默认读取一个名为appsettings.json的Json文件并把它的内容添加到配置文件

拷贝前面的内容到appsettings.json

{ ?"ClassNo": "1", ?"ClassDesc": "ASP.NET Core 101", ?"Students": [ ?????{ ???????"name": "mingsonzheng", ???????"age": "18" ?????}, ?????{ ???????"name": "jim", ???????"age": "28" ?????}, ?????{ ???????"name": "tom", ???????"age": "38" ?????} ?]}

在Startup.cs中通过Bind读取配置

app.Run(async (context) =>{ ???var myClass = new Class(); ???Configuration.Bind(myClass);// Bind读取配置 ???await context.Response.WriteAsync($"ClassNo: { myClass.ClassNo}"); ???await context.Response.WriteAsync($"ClassDesc: { myClass.ClassDesc}"); ???await context.Response.WriteAsync($" {myClass.Students.Count } Students");});

完整Startup.cs

using System;using System.Collections.Generic;using System.Linq;using System.Threading.Tasks;using Microsoft.AspNetCore.Builder;using Microsoft.AspNetCore.Hosting;using Microsoft.AspNetCore.Http;using Microsoft.Extensions.Configuration;using Microsoft.Extensions.DependencyInjection;namespace OptionsBindSample{ ???public class Startup ???{ ???????public IConfiguration Configuration { get; set; } ???????// 通过依赖注入添加configuration ???????public Startup(IConfiguration configuration) ???????{ ???????????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);// Bind读取配置 ???????????????await context.Response.WriteAsync($"ClassNo: { myClass.ClassNo}"); ???????????????await context.Response.WriteAsync($"ClassDesc: { myClass.ClassDesc}"); ???????????????await context.Response.WriteAsync($" {myClass.Students.Count } Students"); ???????????}); ???????} ???}}

启动项目

任务13：在Core Mvc中使用Options

在项目OptionsBindSample新建三个文件夹目录如下

在Controllers文件夹右键，添加一个控制器，默认，HomeController

在Home文件夹右键，添加一个视图，默认，Index

在Startup.cs中注释掉这一段代码，不然会把整个管道提交，只输出这一段

//app.Run(async (context) =>//{// ???var myClass = new Class();// ???Configuration.Bind(myClass);// Bind读取配置// ???await context.Response.WriteAsync($"ClassNo: { myClass.ClassNo}");// ???await context.Response.WriteAsync($"ClassDesc: { myClass.ClassDesc}");// ???await context.Response.WriteAsync($" {myClass.Students.Count } Students");//});

依赖注入配置添加MVC

services.AddMvc();

使用默认路由

app.UseMvcWithDefaultRoute();

HomeController中通过IOptions方式依赖注入

using System;using System.Collections.Generic;using System.Linq;using System.Threading.Tasks;using Microsoft.AspNetCore.Mvc;using Microsoft.Extensions.Options;namespace OptionsBindSample.Controllers{ ???public class HomeController : Controller ???{ ???????private readonly Class _myClass; ???????// 通过IOptions方式依赖注入 ???????public HomeController(IOptions<Class> classAccesser) ???????{ ???????????_myClass = classAccesser.Value; ???????} ???????public IActionResult Index() ???????{ ???????????return View(_myClass); ???????} ???}}

在Index中定义模型，输出

@model OptionsBindSample.Class@{ ???ViewData["Title"] = "Index";}<h2>Index</h2><h4>Class No: @Model.ClassNo</h4><h4>Class Desc: @Model.ClassDesc</h4><h3> ???Students:</h3><div> ???@foreach (var student in Model.Students) ???{ ???????<span>Name: @student.Name</span> ???????<span>Age: @student.Age</span> ???}</div>

注册Class,可以通过Configuration读取到option

services.Configure<Class>(Configuration);

Startup.cs完整代码

using System;using System.Collections.Generic;using System.Linq;using System.Threading.Tasks;using Microsoft.AspNetCore.Builder;using Microsoft.AspNetCore.Hosting;using Microsoft.AspNetCore.Http;using Microsoft.Extensions.Configuration;using Microsoft.Extensions.DependencyInjection;namespace OptionsBindSample{ ???public class Startup ???{ ???????public IConfiguration Configuration { get; set; } ???????// 通过依赖注入添加configuration ???????public Startup(IConfiguration configuration) ???????{ ???????????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) ???????{ ???????????// 注册Class,可以通过Configuration读取到option ???????????services.Configure<Class>(Configuration); ???????????// 依赖注入配置添加MVC ???????????services.AddMvc(); ???????} ???????// 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(); ???????????} ???????????// 使用默认路由 ???????????app.UseMvcWithDefaultRoute(); ???????????//app.Run(async (context) => ???????????//{ ???????????// ???var myClass = new Class(); ???????????// ???Configuration.Bind(myClass);// Bind读取配置 ???????????// ???await context.Response.WriteAsync($"ClassNo: { myClass.ClassNo}"); ???????????// ???await context.Response.WriteAsync($"ClassDesc: { myClass.ClassDesc}"); ???????????// ???await context.Response.WriteAsync($" {myClass.Students.Count } Students"); ???????????//}); ???????} ???}}

启动项目

如果仅仅在视图中使用options的话，HomeController的代码有点多余，可以直接在视图中注入

Index

@using Microsoft.Extensions.Options;@inject IOptions<OptionsBindSample.Class> ClassAccesser@{ ???ViewData["Title"] = "Index";}<h2>Index</h2><h4>Class No: @ClassAccesser.Value.ClassNo</h4><h4>Class Desc: @ClassAccesser.Value.ClassDesc</h4><h3> ???Students:</h3><div> ???@foreach (var student in ClassAccesser.Value.Students) ???{ ???????<span>Name: @student.Name</span> ???????<span>Age: @student.Age</span> ???}</div>

HomeController

using System;using System.Collections.Generic;using System.Linq;using System.Threading.Tasks;using Microsoft.AspNetCore.Mvc;using Microsoft.Extensions.Options;namespace OptionsBindSample.Controllers{ ???public class HomeController : Controller ???{ ???????public IActionResult Index() ???????{ ???????????return View(); ???????} ???}}

启动项目可以得到同样结果

任务14：配置的热更新

ASP.NET修改web.config后站点会自动重启实现热更新

ASP.NET Core不同，实现如下：

将Index的这一行

@inject IOptions<OptionsBindSample.Class> ClassAccesser

修改为

@inject IOptionsSnapshot<OptionsBindSample.Class> ClassAccesser

启动项目

修改appsettings的ClassNo为222，保存

 ?"ClassNo": "222",

刷新网页

实现原理

对比控制台程序JsonComfigSample的Program读取配置文件

 ???????????// 第二个参数表示文件不存在时是否抛异常 ???????????// 第三个参数表示配置文件更新的时候是否重新加载 ???????????var builder = new ConfigurationBuilder() ???????????????.AddJsonFile("class.json",false,true);

而在ASP.NET Core程序OptionsBindSample在Program中的CreateDefaultBuilder的源码实现了

 ???????public static IWebHostBuilder CreateWebHostBuilder(string[] args) => ???????????WebHost.CreateDefaultBuilder(args) ???????????????.UseStartup<Startup>();

WebHost源码：
https://github.com/aspnet/MetaPackages/blob/master/src/Microsoft.AspNetCore/WebHost.cs

源码里面实现热更新（165行）

config.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true) ?????.AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true, reloadOnChange: true);

由于它是WebHostBuilder的一个扩展函数，所以可以覆盖该方法

public static IWebHostBuilder CreateWebHostBuilder(string[] args) => ???WebHost.CreateDefaultBuilder(args) ???????// 如果业务场景不需要一个线程一直关注配置文件变更，可以关闭热更新 ???????.ConfigureAppConfiguration(config => { config.AddJsonFile("appsettings.json", false, false); }) ???????.UseStartup<Startup>();

启动项目，修改配置文件，保存，刷新网页，内容不会热更新

任务15：配置框架设计浅析

本作品采用知识共享署名-非商业性使用-相同方式共享 4.0 国际许可协议进行许可。

欢迎转载、使用、重新发布，但务必保留文章署名 郑子铭 （包含链接： http://www.cnblogs.com/MingsonZheng/ ），不得用于商业目的，基于本文修改后的作品务必以相同的许可发布。

如有任何疑问，请与我联系 (504025730@qq.com) 。

ASP.NET Core快速入门（Jessetalk）（第2章：配置管理）

原文地址：https://www.cnblogs.com/MingsonZheng/p/10312209.html