前言：在与传统的asp.net MVC项目相比,.net core项目在项目目录的文件结构上和功能上与前者都有很大的区别。例如：在.net core中使用Startup.cs取代Global.asax文件用于加载应用程序的配置和各种启动项。appsettings.json取代web.config文件用于存储应用程序所需的配置参数等等。。。

OK！步入正题,下面来说一下如何读取Json配置文件中的参数。

第一种:使用IConfiguration接口

我们先在appsettings.json中配置好数据库连接字符串,然后读取它

{ "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 ReadJson() { //读参 string conn = _configuration["Connection:dbContent"]; return ""; } }}

当然也可以读取数组形式的json,一样的先在appsettings.json中写好配置参数，如下：

{ "Connection": { "dbContent": "Data Source=.;Initial Catalog=test;User ID=sa;Password=123456" }, //------------------------ "Content": [ { "Trade_name": { "test1": "小熊饼干", "test2": "旺仔QQ糖", "test3": "娃哈哈牛奶" } } ], //------------------------ "Logging": { "LogLevel": { "Default": "Information", "Microsoft": "Warning", "Microsoft.Hosting.Lifetime": "Information" } }, "AllowedHosts": "*"}

比如我们想读取test1

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

第二种：使用IOptions来读取json配置文件

先把NuGet包导进项目：Microsoft.Extensions.Options.ConfigurationExtensions

首先在appsettings.json中添加节点如下

{ "Connection": { "dbContent": "Data Source=.;Initial Catalog=test;User ID=sa;Password=123456" }, //------------------------ "Content": [ { "Trade_name": { "test1": "小熊饼干", "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": "实验小学", "Class": "中班", "Number": "15人" }, "Region": { "Province": "湖北", "City": "武汉", "Area": "洪山区" }, "Detailed_address": [ { "Address": "佳园路207号" } ] } } //==============================}

然和再建立一个与这个节点”相同”的类

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 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中添加如下代码

#region 服务注册,在控制器中通过注入的形式使用 services.AddOptions(); services.Configure(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": "小熊饼干", "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": "实验小学", "Class": "中班", "Number": "15人" }, "Region": { "Province": "湖北", "City": "武汉", "Area": "洪山区" }, "Detailed_address": [ { "Address": "佳园路207号" } ] } } //==============================}

第三种：这种应该比较常见,任意读取自定义的json文件

首先建立一个json文件

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

再建一个类,封装一个方法

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() { //这句代码会读取read_json.json中的内容 return new ConfigurationBuilder().AddJsonFile("read_json.json") .Build(); } }}

在控制器中调用：

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

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