.Net Core如何讀取Json配置文件中的參數

.Net Core如何讀取Json配置文件中的參數？針對這個問題，這篇文章給出了相對應的分析和解答，希望能幫助更多想解決這個問題的朋友找到更加簡單易行的辦法。

.NET Core 是.NET Framework的新一代版本，是微軟開發的第一個官方版本，具有跨平臺 (Windows、Mac OSX、Linux) 能力的應用程序開發框架 (Application Framework)，未來也將會支持 FreeBSD 與 Alpine 平臺，也是微軟在一開始發展時就開源的軟件平臺，它經常也會拿來和現有的開源 .NET 平臺 Mono 比較。

第一種：使用IOptions<T>來讀取json配置文件

先把NuGet包導進項目：Microsoft.Extensions.Options.ConfigurationExtensions

首先在appsettings.json中添加節點如下

{
  "Connection": {
    "dbContent": "Data Source=.;Initial Catalog=test;User ID=sa;Password=123456"
  },

  //------------------------
  "Content": [
    {
      "Trade_name": {
        "test1": "小熊餅干",
        "test2": "旺仔QQ糖",
        "test3": "娃哈哈牛奶"
      }
    }
  ],
  //------------------------

  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*",

  //==============================
  "Information": {
    "school": {
      "Introduce": {
        "Name": "實驗小學",
        "Class": "中班",
        "Number": "15人"
      },
      "Region": {
        "Province": "湖北",
        "City": "武漢",
        "Area": "洪山區"
      },
      "Detailed_address": [
        {
          "Address": "佳園路207號"
        }
      ]
    }
  }
  //==============================
}

然和再建立一個與這個節點"相同"的類

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace Read.json
{
    public class Information
    {
        public School school { get; set; }
    }
    public class School
    {
        public Introduce Introduce { get; set; }

        public Region Region { get; set; }

        public List<Detailed_address> data { get; set; }

    }
    public class Introduce
    {
        public string Name { get; set; }
        public string Class { get; set; }
        public string Number { get; set; }
    }

    public class Region
    {
        public string Province { get; set; }
        public string City { get; set; }
        public string Area { get; set; }
    }
    public class Detailed_address
    {
        public string Address { get; set; }
    }
}

在Startup中添加如下代碼

            #region 服務注冊,在控制器中通過注入的形式使用
            services.AddOptions();
            services.Configure<Information>(Configuration.GetSection("Information"));            #endregion

控制器中使用：

{
  "Connection": {
    "dbContent": "Data Source=.;Initial Catalog=test;User ID=sa;Password=123456"
  },

  //------------------------
  "Content": [
    {
      "Trade_name": {
        "test1": "小熊餅干",
        "test2": "旺仔QQ糖",
        "test3": "娃哈哈牛奶"
      }
    }
  ],
  //------------------------

  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*",

  //==============================
  "Information": {
    "school": {
      "Introduce": {
        "Name": "實驗小學",
        "Class": "中班",
        "Number": "15人"
      },
      "Region": {
        "Province": "湖北",
        "City": "武漢",
        "Area": "洪山區"
      },
      "Detailed_address": [
        {
          "Address": "佳園路207號"
        }
      ]
    }
  }
  //==============================
}

第二種：這種應該比較常見,任意讀取自定義的json文件

首先建立一個json文件

{
  "system_version": {
    "Edition": ".Net Core 3.0",
    "Project_Name": "Read.json"
  }
}

再建一個類,封裝一個方法

using Microsoft.Extensions.Configuration;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace Read.json
{
    public class Json_File
    {
        public IConfigurationRoot Read_Json_File()
        {
            //這句代碼會讀取read_json.json中的內容
            return new ConfigurationBuilder().AddJsonFile("read_json.json")
                                             .Build();

        }

    }
}

在控制器中調用：

[HttpGet]
        public async Task<IActionResult> ReadSystemVersion()
        {
            var configuration = _json_File.Read_Json_File();
            string system = "使用的是" + configuration["system_version:Edition"] + "的版本" + "," +
                            "項目名稱是" + configuration["system_version:Project_Name"];
            return Json(new
            {
                data = system
            });
        }

第三種:使用IConfiguration接口

我們先在appsettings.json中配置好數據庫連接字符串,然后讀取它

{
  "Connection": {
    "dbContent": "Data Source=.;Initial Catalog=test;User ID=sa;Password=123456"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*"
}

在控制器中注入IConfiguration接口

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;

namespace Read.json.Controllers
{
    [ApiController]
    [Route("[controller]")]
    public class ReadController : Controller
    {
        private IConfiguration _configuration;
        public ReadController(IConfiguration configuration)
        {
            _configuration = configuration;
        }

        [HttpPost]
        public async Task<string> ReadJson()
        {
            //讀參
            string conn = _configuration["Connection:dbContent"];
            return "";
        }

    }
}

當然也可以讀取數組形式的json,一樣的先在appsettings.json中寫好配置參數，如下：

{
  "Connection": {
    "dbContent": "Data Source=.;Initial Catalog=test;User ID=sa;Password=123456"
  },

  //------------------------
  "Content": [
    {
      "Trade_name": {
        "test1": "小熊餅干",
        "test2": "旺仔QQ糖",
        "test3": "娃哈哈牛奶"
      }
    }
  ],
  //------------------------

  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*"
}

比如我們想讀取test1

string commodity_test1 = _configuration["Content:0:Trade_name:test1"];

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