在.Net Framework中，配置文件一般采用的是XML格式的，.NET Framework提供了专门的ConfigurationManager来读取配置文件的内容，.net core中推荐使用json格式的配置文件，那么在.net core中该如何读取json文件呢？
1、在Startup类中读取json配置文件
1、使用Configuration直接读取
看下面的代码：
public IConfiguration Configuration { get; }Configuration属性就是.net core中提供的用来读取json文件。例如：
public void Configure(IApplicationBuilder app, IHostingEnvironment env){ ???????????string option1 = $"option1 = {this.Configuration["Option1"]}"; ???????????string option2 = $"option2 = {this.Configuration["Option2"]}"; ???????????string suboption1 = $"suboption1 = {this.Configuration["subsection:suboption1"]}"; ???????????// 读取数组 ???????????string name1 = $"Name={this.Configuration["student:0:Name"]} "; ???????????string age1 = $"Age= {this.Configuration["student:0:Age"]}"; ???????????string name2 = $"Name={this.Configuration["student:1:Name"]}"; ???????????string age2 = $"Age= {this.Configuration["student:1:Age"]}"; ???????????// 输出 ???????????app.Run(c => c.Response.WriteAsync(option1+"\r\n"+option2+ "\r\n"+suboption1+ "\r\n"+name1+ "\r\n"+age1+ "\r\n"+name2+ "\r\n"+age2)); ???????????if (env.IsDevelopment()) ???????????{ ???????????????app.UseDeveloperExceptionPage(); ???????????} ???????????else ???????????{ ???????????????app.UseHsts(); ???????????} ???????????app.UseHttpsRedirection(); ???????????app.UseMvc();}结果：
2、使用IOptions接口
1、定义实体类
public class MongodbHostOptions{ ???????/// <summary> ???????/// 连接字符串 ???????/// </summary> ???????public string Connection { get; set; } ???????/// <summary> ???????/// 库 ???????/// </summary> ???????public string DataBase { get; set; } ???????public string Table { get; set; }}2、修改json文件
在appsettings.json文件中添加MongodbHost节点：
{ ?"Logging": { ???"LogLevel": { ?????"Default": "Warning" ???} ?}, ?"option1": "value1_from_json", ?"option2": 2, ?"subsection": { ???"suboption1": "subvalue1_from_json" ?}, ?"student": [ ???{ ?????"Name": "Gandalf", ?????"Age": "1000" ???}, ???{ ?????"Name": "Harry", ?????"Age": "17" ???} ?], ?"AllowedHosts": "*", ?//MongoDb ?"MongodbHost": { ???"Connection": "mongodb://127.0.0.1:27017", ???"DataBase": "TemplateDb", ???"Table": "CDATemplateInfo" ?}}注意：
MongodbHost里面的属性名必须要和定义的实体类里面的属性名称一致。
3、在StartUp类里面配置
添加OptionConfigure方法绑定
private void OptionConfigure(IServiceCollection services){ ?????//MongodbHost信息 ?????services.Configure<MongodbHostOptions>(Configuration.GetSection("MongodbHost"));}在ConfigureServices方法中调用上面定义的方法：
public void ConfigureServices(IServiceCollection services){ ????// 调用OptionConfigure方法 ????OptionConfigure(services); ???????????????services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);}在控制器中使用，代码如下：
using System;using System.Collections.Generic;using System.Linq;using System.Threading.Tasks;using Microsoft.AspNetCore.Http;using Microsoft.AspNetCore.Mvc;using Microsoft.Extensions.Options;namespace ReadJsonDemo.Controllers{ ???[Route("api/[controller]")] ???[ApiController] ???public class MongodbController : ControllerBase ???{ ???????private readonly MongodbHostOptions _mongodbHostOptions; ???????/// <summary> ???????/// 通过构造函数注入 ???????/// </summary> ???????/// <param name="mongodbHostOptions"></param> ???????public MongodbController(IOptions<MongodbHostOptions> mongodbHostOptions) ???????{ ???????????_mongodbHostOptions = mongodbHostOptions.Value; ???????} ???????[HttpGet] ???????public async Task Get() ???????{ ??????????await Response.WriteAsync("Connection:" + _mongodbHostOptions.Connection + "\r\nDataBase;" + _mongodbHostOptions.DataBase + "\r\nTable:" + _mongodbHostOptions.Table); ???????} ???}}运行结果：
3、读取自定义json文件
在上面的例子中都是读取的系统自带的appsettings.json文件，那么该如何读取我们自己定义的json文件呢？这里可以使用ConfigurationBuilder类。
实例化类
var builder = new ConfigurationBuilder();
添加方式1
builder.AddJsonFile("path", false, true);其中path表示json文件的路径，包括路径和文件名。
添加方式2
builder.Add(new JsonConfigurationSource {Path= "custom.json",Optional=false,ReloadOnChange=true }).Build()具体代码如下：
private void CustomOptionConfigure(IServiceCollection services){ ???????????IConfiguration _configuration; ???????????var builder = new ConfigurationBuilder(); ???????????// 方式1 ???????????//_configuration = builder.AddJsonFile("custom.json", false, true).Build(); ???????????// 方式2 ???????????_configuration = builder.Add(new JsonConfigurationSource {Path= "custom.json",Optional=false,ReloadOnChange=true }).Build(); ???????????services.Configure<WebSiteOptions>(_configuration.GetSection("WebSiteConfig"));}ConfigureServices方法如下：
public void ConfigureServices(IServiceCollection services){ ???????????// 调用OptionConfigure方法 ???????????OptionConfigure(services); ???????????CustomOptionConfigure(services); ???????????services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);}控制器代码如下：
using System;using System.Collections.Generic;using System.Linq;using System.Threading.Tasks;using Microsoft.AspNetCore.Http;using Microsoft.AspNetCore.Mvc;using Microsoft.Extensions.Options;namespace ReadJsonDemo.Controllers{ ???[Route("api/[controller]")] ???[ApiController] ???public class MongodbController : ControllerBase ???{ ???????private readonly MongodbHostOptions _mongodbHostOptions; ???????private readonly WebSiteOptions _webSiteOptions; ???????/// <summary> ???????/// 通过构造函数注入 ???????/// </summary> ???????/// <param name="mongodbHostOptions"></param> ???????public MongodbController(IOptions<MongodbHostOptions> mongodbHostOptions,IOptions<WebSiteOptions> webSiteOptions) ???????{ ???????????_mongodbHostOptions = mongodbHostOptions.Value; ???????????_webSiteOptions = webSiteOptions.Value; ???????} ???????[HttpGet] ???????public async Task Get() ???????{ ??????????await Response.WriteAsync("Connection:" + _mongodbHostOptions.Connection + "\r\nDataBase;" + _mongodbHostOptions.DataBase + "\r\nTable:" + _mongodbHostOptions.Table); ???????????await Response.WriteAsync("\r\n"); ???????????await Response.WriteAsync("WebSiteName:" + _webSiteOptions.WebSiteName + "\r\nWebSiteUrl;" + _webSiteOptions.WebSiteUrl); ???????} ???}}二、在类库中读取json文件
在上面的示例中都是直接在应用程序中读取的，那么如何在单独的类库中读取json文件呢？看下面的示例代码：
using Microsoft.Extensions.Configuration;using Microsoft.Extensions.DependencyInjection;using Microsoft.Extensions.Options;using System;using System.Collections.Generic;using System.IO;using System.Text;namespace Common{ ???public class JsonConfigHelper ???{ ???????public static T GetAppSettings<T>(string fileName, string key) where T : class, new() ???????{ ???????????// 获取bin目录路径 ???????????var directory = AppContext.BaseDirectory; ???????????directory = directory.Replace("\\", "/"); ???????????var filePath = $"{directory}/{fileName}"; ???????????if (!File.Exists(filePath)) ???????????{ ???????????????var length = directory.IndexOf("/bin"); ???????????????filePath = $"{directory.Substring(0, length)}/{fileName}"; ???????????} ???????????IConfiguration configuration; ???????????var builder = new ConfigurationBuilder(); ???????????????????????builder.AddJsonFile(filePath, false, true); ???????????configuration = builder.Build(); ???????????var appconfig = new ServiceCollection() ???????????????.AddOptions() ???????????????.Configure<T>(configuration.GetSection(key)) ???????????????.BuildServiceProvider() ???????????????.GetService<IOptions<T>>() ???????????????.Value; ???????????return appconfig; ???????} ???}}注意：这里要添加如下几个程序集，并且要注意添加的程序集的版本要和.net core web项目里面的程序集版本一致，否则会报版本冲突的错误
1、Microsoft.Extensions.Configuration
2、Microsoft.Extensions.configuration.json
3、Microsoft.Extensions.Options
4、Microsoft.Extensions.Options.ConfigurationExtensions
5、Microsoft.Extensions.Options
json文件如下：
{ ?"WebSiteConfig": { ???"WebSiteName": "CustomWebSite", ???"WebSiteUrl": "https:localhost:12345" ?}, ?"DbConfig": { ???"DataSource": "127.0.0.1", ???"InitialCatalog": "MyDb", ???"UserId": "sa", ???"Password": "123456" ?}}DbHostOptions实体类定义如下：
using System;using System.Collections.Generic;using System.Linq;using System.Threading.Tasks;namespace ReadJsonDemo{ ???public class DbHostOptions ???{ ???????public string DataSource { get; set; } ???????public string InitialCatalog { get; set; } ???????public string UserId { get; set; } ???????public string Password { get; set; } ???}}注意：这里的DbHostOptions实体类应该建在单独的类库中，这里为了演示方便直接建在应用程序中了。
在控制器中调用：
using System;using System.Collections.Generic;using System.Linq;using System.Threading.Tasks;using Common;using Microsoft.AspNetCore.Http;using Microsoft.AspNetCore.Mvc;using Microsoft.Extensions.Options;namespace ReadJsonDemo.Controllers{ ???[Route("api/[controller]")] ???[ApiController] ???public class MongodbController : ControllerBase ???{ ???????private readonly MongodbHostOptions _mongodbHostOptions; ???????private readonly WebSiteOptions _webSiteOptions; ???????/// <summary> ???????/// 通过构造函数注入 ???????/// </summary> ???????/// <param name="mongodbHostOptions"></param> ???????public MongodbController(IOptions<MongodbHostOptions> mongodbHostOptions,IOptions<WebSiteOptions> webSiteOptions) ???????{ ???????????_mongodbHostOptions = mongodbHostOptions.Value; ???????????_webSiteOptions = webSiteOptions.Value; ???????} ???????[HttpGet] ???????public async Task Get() ???????{ ???????????DbHostOptions dbOptions = JsonConfigHelper.GetAppSettings<DbHostOptions>("custom.json", "DbConfig"); ???????????await Response.WriteAsync("DataSource:" + dbOptions.DataSource + "\r\nInitialCatalog;" + dbOptions.InitialCatalog+ "\r\nUserId:"+dbOptions.UserId+ "\r\nPassword"+dbOptions.Password); ???????????await Response.WriteAsync("\r\n"); ???????????await Response.WriteAsync("Connection:" + _mongodbHostOptions.Connection + "\r\nDataBase;" + _mongodbHostOptions.DataBase + "\r\nTable:" + _mongodbHostOptions.Table); ???????????await Response.WriteAsync("\r\n"); ???????????await Response.WriteAsync("WebSiteName:" + _webSiteOptions.WebSiteName + "\r\nWebSiteUrl;" + _webSiteOptions.WebSiteUrl); ??????????????????} ???}}运行结果：
.net core读取json格式的配置文件
原文地址：https://www.cnblogs.com/dotnet261010/p/10172961.html