ASP.NET Core快速入门（第2章：配置管理）--学习笔记
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ASP.NET Core快速入门（第2章：配置管理）--学习笔记
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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.dllname: 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Builderbuilder.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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