ASP.NET Core 入门教程1 ASP.NET Core 读取配置文件

ASP.NET Core 对于读取配置文件，和之前.NET Framework 有了很大的区别，下面将介绍一下在学习ASP.NET Core过程中的配置文件的读取操作。文章末尾有源代码提供下载学习。

1、用VS2019新建一个ASP.NET Core Web 应用程序，MVC项目，如下图：

2、 “key:"value" 格式读取读取配置文件

/*
* 按照关键字直接读取 2种方法 0级目录型如 “key:"value" 格式
* "TestReadConfig": "这是从配置文件读取的关键字为【TestReadConfig】的内容。",
*/
var testReadConfig1 = Configuration.GetValue(typeof(string), "TestReadConfig");
//或者这种写法也可以
testReadConfig1 = Configuration.GetValue<string>("TestReadConfig");

//第二种写法
var testReadConfig2 = Configuration.GetSection("TestReadConfig").Value;

3、"Key": {"key": "value" } ==>"ConnectionStrings": {"Default": "Server=;" } 2种方法读取

/*
* 按照关键字直接读取 2种方法 1级目录
* "ConnectionStrings": {"Default": "Server=;" }
*/

var connectionStrings1 = Configuration.GetSection("ConnectionStrings").GetChildren().FirstOrDefault()?.Value;//默认取第一个
var connectionStrings2 = Configuration.GetSection("ConnectionStrings:Default").Value;//键值对取值

/*
键值对读取方法
"Student": {
"Name": "小明",
"Age": 18
}
*/
var keyValueName = Configuration.GetSection("Student:Name").Value;
var keyValueAge = Configuration.GetSection("Student:Age").Value;

4、组合实体类

/*
* 组合实体类
* "Student": {
"Name": "小明",
"Age": 18
}
*/

int age = -99;
var student = Configuration.GetSection("Student").GetChildren()
.Select(config => new Student()
{
Name = config["Name"],
Age = int.TryParse(config["Age"], out age) == true ? age : age,
});

代码如下：

  1 using System;
  2 using System.Collections.Generic;
  3 using System.Linq;
  4 using System.Threading.Tasks;
  5 using System.Runtime;
  6 using Microsoft.AspNetCore.Builder;
  7 using Microsoft.AspNetCore.Hosting;
  8 using Microsoft.AspNetCore.HttpsPolicy;
  9 using Microsoft.Extensions.Configuration;
 10 using Microsoft.Extensions.DependencyInjection;
 11 using Microsoft.Extensions.Hosting;
 12 
 13 namespace WebApplicationStudy
 14 {
 15     public class Startup
 16     {
 17         public Startup(IConfiguration configuration)
 18         {
 19             Configuration = configuration;
 20         }
 21 
 22         public IConfiguration Configuration { get; }
 23 
 24         // This method gets called by the runtime. Use this method to add services to the container.
 25         public void ConfigureServices(IServiceCollection services)
 26         {
 27             services.AddControllersWithViews();
 28         }
 29 
 30         // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
 31         public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
 32         {
 33             if (env.IsDevelopment())
 34             {
 35                 app.UseDeveloperExceptionPage();
 36             }
 37             else
 38             {
 39                 app.UseExceptionHandler("/Home/Error");
 40                 // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
 41                 app.UseHsts();
 42             }
 43 
 44             app.UseHttpsRedirection();
 45             app.UseStaticFiles();
 46 
 47             app.UseRouting();
 48 
 49             app.UseAuthorization();
 50 
 51             app.UseEndpoints(endpoints =>
 52             {
 53                 endpoints.MapControllerRoute(
 54                     name: "default",
 55                     pattern: "{controller=Home}/{action=Index}/{id?}");
 56             });
 57             /*
 58             {
 59               "Logging": {
 60                 "LogLevel": {
 61                   "Default": "Information",
 62                   "Microsoft": "Warning",
 63                   "Microsoft.Hosting.Lifetime": "Information"
 64                 }
 65               },
 66               "AllowedHosts": "*",
 67 
 68               "ConnectionStrings": {
 69                 "Default": "Server=;"
 70               },
 71               "TestReadConfig": "这是从配置文件读取的关键字为【TestReadConfig】的内容。",
 72               "Student": {
 73                 "Name": "小明",
 74                 "Age": 18
 75               }
 76             }
 77              */
 78             /*
 79              * 按照关键字直接读取 2种方法 0级目录 型如 “key:"value" 格式
 80              * "TestReadConfig": "这是从配置文件读取的关键字为【TestReadConfig】的内容。",
 81              */
 82             var testReadConfig1 = Configuration.GetValue(typeof(string), "TestReadConfig");
 83             //或者这种写法也可以
 84             testReadConfig1 = Configuration.GetValue<string>("TestReadConfig");
 85 
 86             //第二种写法
 87             var testReadConfig2 = Configuration.GetSection("TestReadConfig").Value;
 88 
 89             /*
 90             * 按照关键字直接读取 2种方法 1级目录
 91             *  "ConnectionStrings": {"Default": "Server=;" }
 92             */
 93             var connectionStrings1 = Configuration.GetSection("ConnectionStrings").GetChildren().FirstOrDefault()?.Value;//默认取第一个
 94             var connectionStrings2 = Configuration.GetSection("ConnectionStrings:Default").Value;//键值对取值
 95 
 96 
 97             /*
 98              键值对读取方法
 99               "Student": {
100                         "Name": "小明",
101                         "Age": 18
102                       }
103              */
104             var keyValueName = Configuration.GetSection("Student:Name").Value;
105             var keyValueAge = Configuration.GetSection("Student:Age").Value;
106 
107             /*
108              * 组合实体类
109              *   "Student": {
110                         "Name": "小明",
111                         "Age": 18
112                       }
113              */
114 
115             int age = -99;
116             var student = Configuration.GetSection("Student").GetChildren()
117                 .Select(config => new Student()
118                 {
119                     Name = config["Name"],
120                     Age = int.TryParse(config["Age"], out age) == true ? age : age,
121                 });
122 
123             #region MyRegion
124             /*var studentIConfigurationSectionList = Configuration.GetSection("Student").GetChildren().ToList<IConfigurationSection>();
125            if (studentIConfigurationSectionList !=null && studentIConfigurationSectionList.Count>0)
126            {
127                foreach (var item in studentIConfigurationSectionList)
128                {
129 
130                }
131            }*/
132             #endregion
133         }
134 
135         private class Student
136         {
137             public string? Name { get; set; }
138             public int? Age { get; set; }
139         }
140     }
141 }

appsettings.json配置文件如下：

 1 {
 2   "Logging": {
 3     "LogLevel": {
 4       "Default": "Information",
 5       "Microsoft": "Warning",
 6       "Microsoft.Hosting.Lifetime": "Information"
 7     }
 8   },
 9 
10   //方法1 Configuration.GetValue(typeof(string), "TestReadConfig"); 或者 Configuration.GetValue<string>("TestReadConfig");
11   //方法2  Configuration.GetSection("TestReadConfig").Value;
12   "AllowedHosts": "*",
13   "TestReadConfig": "这是从配置文件读取的关键字为【TestReadConfig】的内容。",
14 
15   //方法1 Configuration.GetSection("ConnectionStrings").GetChildren().FirstOrDefault()?.Value;//默认取第一个
16   //方法2 Configuration.GetSection("ConnectionStrings:Default").Value; //键值对取值
17   "ConnectionStrings": {
18     "Default": "Server=;"
19   },
20 
21   //组合实体类
22   // int age = -99;
23   // var student = Configuration.GetSection("Student").GetChildren()
24   // .Select(config => new Student()
25   // {
26   //Name = config["Name"],
27   // Age = int.TryParse(config["Age"], out age) == true ? age : age,
28   //});
29   "Student": {
30     "Name": "小明",
31     "Age": 18
32   }
33 }

代码截图如下(图片可能有点小，需要放大来看)：

附上源代码，一起学习

下载地址：

https://files-cdn.cnblogs.com/files/ningxt/ASP.NETCore%E5%85%A5%E9%97%A81%E8%AF%BB%E5%8F%96%E9%85%8D%E7%BD%AE%E6%96%87%E4%BB%B6_20191225_Ning.ASP.NETCore3.Study.7z

posted on 2019-12-25 14:26 不高兴的小宁童鞋阅读(385) 评论(0) 编辑收藏举报

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