.net core读取json格式的配置文件

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？

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::Name"]} ";
            string age1 = $"Age= {this.Configuration["student::Age"]}";
            string name2 = $"Name={this.Configuration["student::Name"]}";
            string age2 = $"Age= {this.Configuration["student::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": ,
  "subsection": {
    "suboption1": "subvalue1_from_json"
  },
  "student": [
    {
      "Name": "Gandalf",
      "Age": ""
    },
    {
      "Name": "Harry",
      "Age": ""
    }
  ],
  "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": ""
  }
}

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：