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課程鏈接：http://video.jessetalk.cn/course/explore

良心課程，大家一起來學習哈！

任務9：配置介紹

• 命令行配置

• Json文件配置

• 從配置文件文本到c#對象實例的映射 - Options 與 Bind

• 配置文件熱更新

• 框架設計：Configuration

任務10：命令行配置

新建項目CommandLineSample--控制臺應用（.NET Core）

管理NuGet程序包--下載microsoft.aspnetcore.all

傳入參數

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();
}
}
}

項目右鍵--調試--輸入參數：name=mingsonzheng age=18

啟動項目

默認參數

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();
}
}
}

清空應用程序參數

啟動項目

通過PowerShell運行程序，默認參數與傳入參數對比

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

任務11：Json文件配置

新建項目JsonComfigSample--控制臺應用（.NET Core）

管理NuGet程序包--下載microsoft.aspnetcore.all

添加Json文件：項目右鍵--添加新建項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目錄下，所以默認不會被編譯，文件右鍵屬性，修改為始終復制

using System;
using Microsoft.Extensions.Configuration;

namespace JsonComfigSample
{
class Program
{
static void Main(string[] args)
{
var builder = new ConfigurationBuilder()
.AddJsonFile("class.json");

Console.ReadLine();
}
}
}

啟動項目，可以看到class.json被復制到bin\Debug目錄，這樣dll就可以讀取到class.json文件

讀取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");

// 調用Build之前請確保拷貝的class.json文件沒有格式錯誤
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();
}
}
}

啟動項目

任務12：Bind讀取配置到C#實例

新建ASP.NET Core Web 應用程序OptionsBindSample，直接選擇 空，確定

在Startup.cs中通過依賴注入添加configuration

public IConfiguration Configuration { get; set; }

public Startup(IConfiguration configuration)
{
Configuration = configuration;
}

項目右鍵，新建項，添加一個類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; }
}
}

項目右鍵，新建項，添加一個Json文件appsettings.json

為什么取名appsettings.json呢？

因為Program.cs中的CreateDefaultBuilder默認讀取一個名為appsettings.json的Json文件并把它的內容添加到配置文件

拷貝前面的內容到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中通過Bind讀取配置

app.Run(async (context) =>
{
var myClass = new Class();
Configuration.Bind(myClass);// 實現配置文件信息與對象的映射

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; }

// 通過依賴注入添加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讀取配置

await context.Response.WriteAsync($"ClassNo: { myClass.ClassNo}");
await context.Response.WriteAsync($"ClassDesc: { myClass.ClassDesc}");
await context.Response.WriteAsync($" {myClass.Students.Count } Students");
});
}
}
}

啟動項目

任務13：在Core Mvc中使用Options

在項目OptionsBindSample新建三個文件夾目錄如下

在Controllers文件夾右鍵，添加一個控制器，默認，HomeController

在Home文件夾右鍵，添加一個視圖，默認，Index

在Startup.cs中注釋掉這一段代碼，不然會把整個管道提交，只輸出這一段

//app.Run(async (context) =>
//{
// var myClass = new Class();
// Configuration.Bind(myClass);// Bind讀取配置

// await context.Response.WriteAsync($"ClassNo: { myClass.ClassNo}");
// await context.Response.WriteAsync($"ClassDesc: { myClass.ClassDesc}");
// await context.Response.WriteAsync($" {myClass.Students.Count } Students");
//});

依賴注入配置添加MVC

services.AddMvc();

使用默認路由

app.UseMvcWithDefaultRoute();

HomeController中通過IOptions方式依賴注入

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;

// 通過IOptions方式依賴注入
public HomeController(IOptions<Class> classAccesser)
{
_myClass = classAccesser.Value;
}

public IActionResult Index()
{
return View(_myClass);
}
}
}

在Index中定義模型，輸出

@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>

注冊Class,可以通過Configuration讀取到option

services.Configure<Class>(Configuration);

Startup.cs完整代碼

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; }

// 通過依賴注入添加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)
{
// 注冊Class,可以通過Configuration讀取到option
services.Configure<Class>(Configuration);
// 依賴注入配置添加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();
}

// 使用默認路由
app.UseMvcWithDefaultRoute();

//app.Run(async (context) =>
//{
// var myClass = new Class();
// Configuration.Bind(myClass);// Bind讀取配置

// await context.Response.WriteAsync($"ClassNo: { myClass.ClassNo}");
// await context.Response.WriteAsync($"ClassDesc: { myClass.ClassDesc}");
// await context.Response.WriteAsync($" {myClass.Students.Count } Students");
//});
}
}
}

啟動項目

如果僅僅在視圖中使用options的話，HomeController的代碼有點多余，可以直接在視圖中注入

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();
}
}
}

啟動項目得到同樣結果

任務14：配置的熱更新

ASP.NET修改web.config后站點會自動重啟實現熱更新

ASP.NET Core不同，實現如下：

將Index的這一行

@inject IOptions<OptionsBindSample.Class> ClassAccesser

修改為

@inject IOptionsSnapshot<OptionsBindSample.Class> ClassAccesser

啟動項目

修改appsettings的ClassNo為222，保存

"ClassNo": "222",

刷新網頁

實現原理

對比控制臺程序JsonComfigSample的Program讀取配置文件

// 第二個參數表示文件不存在時是否拋異常
// 第三個參數表示配置文件更新的時候是否重新加載
var builder = new ConfigurationBuilder()
.AddJsonFile("class.json",false,true);

而在ASP.NET Core程序OptionsBindSample在Program中的CreateDefaultBuilder的源碼實現了

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

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

源碼里面實現熱更新（165行）

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

由于它是WebHostBuilder的一個擴展函數，所以可以覆蓋該方法

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
WebHost.CreateDefaultBuilder(args)
// 如果業務場景不需要一個線程一直關注配置文件變更，可以關閉熱更新
.ConfigureAppConfiguration(config => { config.AddJsonFile("appsettings.json", false, false); })
.UseStartup<Startup>();

啟動項目，修改配置文件，保存，刷新網頁，內容不會熱更新

任務15：配置框架設計淺析

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

builder.Add(source);// 將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;
}

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