ASP.NET Core快速入门(第2章:配置管理)- 学习笔记(转载)

时间:2021-04-11 05:10:26

原文地址:https://mp.weixin.qq.com/s?__biz=MjM5NjMzMzE2MA==&mid=2451733443&idx=2&sn=6d01721c55d486df3efaa21dace9de6a&chksm=b13c08c4864b81d23a09f15abe703249d76019c9886509d4d1b73f7d8dd99717d8fee7dc7d91&mpshare=1&scene=1&srcid=&sharer_sharetime=1575242352502&sharer_shareid=03e89b3db7bd7f780e5e6f6aeac19ec0&pass_ticket=RXV14KW7NB%2FaPTT2RIYzlh9XS4HYLkksvZekeGxQBjPoFv3CNqRXbhBdtX512P68#rd

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

ASP.NET Core快速入门(第2章:配置管理)- 学习笔记(转载)

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

ASP.NET Core快速入门(第2章:配置管理)- 学习笔记(转载)

启动项目

ASP.NET Core快速入门(第2章:配置管理)- 学习笔记(转载)

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

ASP.NET Core快速入门(第2章:配置管理)- 学习笔记(转载)

启动项目

ASP.NET Core快速入门(第2章:配置管理)- 学习笔记(转载)

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

ASP.NET Core快速入门(第2章:配置管理)- 学习笔记(转载)

{
"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,文件右键属性,修改为始终复制

ASP.NET Core快速入门(第2章:配置管理)- 学习笔记(转载)

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

ASP.NET Core快速入门(第2章:配置管理)- 学习笔记(转载)

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

ASP.NET Core快速入门(第2章:配置管理)- 学习笔记(转载)

任务12:Bind读取配置到C#实例

新建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);// 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 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

ASP.NET Core快速入门(第2章:配置管理)- 学习笔记(转载)

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

ASP.NET Core快速入门(第2章:配置管理)- 学习笔记(转载)

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

ASP.NET Core快速入门(第2章:配置管理)- 学习笔记(转载)

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

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

ASP.NET Core快速入门(第2章:配置管理)- 学习笔记(转载)

修改appsettings的ClassNo为222,保存

  "ClassNo": "222",

刷新网页

ASP.NET Core快速入门(第2章:配置管理)- 学习笔记(转载)

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

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;
}