ASP.NET Core快速入门（第2章：配置管理）- 学习笔记(转载)
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": "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
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
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
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;
}
