目录
一、在Startup类中读取json配置文件1、使用Configuration直接读取2、使用IOptions接口1、定义实体类2、修改json文件3、在StartUp类里面配置3、读取自定义json文件实例化类 添加方式1添加方式2二、在类库中读取json文件在.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？
一、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+"rn"+option2+ "rn"+suboption1+ "rn"+name1+ "rn"+age1+ "rn"+name2+ "rn"+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
privigure(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 Systemwww.easck.com.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 + "rnDataBase;" + _mongodbHostOptions.DataBase + "rnTable:" + _mongodbHostOptions.Table); await Response.WriteAsync("rn"); await Response.WriteAsync("WebSiteName:" + _webSiteOptions.WebSiteName + "rnWebSiteUrl;" + _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; } }}1、Microsoft.Extensions.Configuration2、Microsoft.Extensions.configuration.json3、Microsoft.Extensions.Options4、Microsoft.Extensions.Options.ConfigurationExtensions5、Microsoft.Extensions.Options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
json文件如下：
{ "WebSiteConfig": { "WebSiteName": "CustomWebSite", "WebSiteUrl": "https:localhost:12345" }, "DbConfig": { "Datwww.easck.comaSource": "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 { www.easck.com 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 + "rnInitialCatalog;" + dbOptions.InitialCatalog+ "rnUserId:"+dbOptions.UserId+ "rnPassword"+dbOptions.Password); await Response.WriteAsync("rn"); await Response.WriteAsync("Connection:" + _mongodbHostOptions.Connection + "rnDataBase;" + _mongodbHostOptions.DataBase + "rnTable:" + _mongodbHostOptions.Table); await Response.WriteAsync("rn"); await Response.WriteAsync("WebSiteName:" + _webSiteOptions.WebSiteName + "rnWebSiteUrl;" + _webSiteOptions.WebSiteUrl); } }}运行结果：
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