ASP.NET Core快速入门（第2章：配置管理）--学习笔记

点击蓝字关注我们

课程链接：/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

新建项目CommandLineSample--控制台应用（.NET Core）

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();

}

}

}

项目右键--调试--输入参数：name=mingsonzheng age=18

启动项目

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对比

PS D:\jessetalk\CommandLineSample\CommandLineSample\bin\Debug\netcoreapp2.1> dotnet CommandLineSample.dll

name: mingsonzheng

age: 18

PS D:\jessetalk\CommandLineSample\CommandLineSample\bin\Debug\netcoreapp2.1> dotnet CommandLineSample.dll name=jim age=22

name: jim

age: 22

任务11：Json文件配置

新建项目JsonComfigSample--控制台应用（.NET Core）

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": " 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，文件右键属性，修改为始终复制

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 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": " 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);// 实现配置文件信息与对象的映射

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 /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 /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();

}

}

}

启动项目得到同样结果

任务14：配置的热更新

修改web.config后站点会自动重启实现热更新

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 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：

/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

var builder = new ConfigurationBuilder();// 初始化Builder

builder.Add(source);// 将source添加到Builder

=>

JsonConfigurationSource source = new

JsonConfigurationSource()

{

Path = "settings.json";

};

var configurationRoot = builder.Build();// Build

=>

foreach(var source in sources)

{

var provider = source.Build();

providers.add(provider);

}

return new ConfigurationRoot(providers);

configurationRoot["Key"]// Use

=>

foreach(var provider in providers.Reverse())

{

string value;

provider.TryGet(Key, out Value)

return value;

}

点“在看”给我一朵小黄花