ASP.NET CORE如何读取json格式配置文件

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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+"\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{        /// 
        /// 连接字符串        /// 
        public string Connection { get; set; }        /// 
        /// 库        /// 
        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(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;        /// 
        /// 通过构造函数注入        /// 
        ///         public MongodbController(IOptions 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(_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;        /// 
        /// 通过构造函数注入        /// 
        ///         public MongodbController(IOptions mongodbHostOptions,IOptions 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(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(configuration.GetSection(key))                .BuildServiceProvider()                .GetService>()                .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;        /// 
        /// 通过构造函数注入        /// 
        ///         public MongodbController(IOptions mongodbHostOptions,IOptions webSiteOptions)        {            _mongodbHostOptions = mongodbHostOptions.Value;            _webSiteOptions = webSiteOptions.Value;        }        [HttpGet]        public async Task Get()        {            DbHostOptions dbOptions = JsonConfigHelper.GetAppSettings("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：

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