C# .NET5.0 读取appsettings.json

基于VS2019，使用步骤：

方式一：

第一步：appsettings.json 定义配置项，可理解为定义对象属性，eg:

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{   "Logging": {     "LogLevel": {       "Default": "Information",       "Microsoft": "Warning",       "Microsoft.Hosting.Lifetime": "Information"     }   },   "MEASSettings":   {     "PrintName": "wula",     "PrintNum": 12   },     "AllowedHosts": "*"   }

第二步：定义实体对象，eg:

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using System;   namespace Test {     public class MEASSettings     {         public string PrintName { get; set; }         public string PrintNum { get; set; }       } }

 第三步：读取配置项公共方法提取，创建DLL(基于.NET 5.0略)

注：需安装如下依赖项，略

 

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using Microsoft.Extensions.Configuration; using Microsoft.Extensions.Configuration.Json; using System;   namespace MEAS.Common {     public class AppsettingsHelper     {         public IConfiguration Configuration { get; set; }           //定义一个用于保存静态变量的实例         private static AppsettingsHelper instance = null;         //定义一个保证线程同步的标识         private static readonly object locker = new object();         //构造函数为私有，使外界不能创建该类的实例         private AppsettingsHelper()         {             Configuration = new ConfigurationBuilder()                 .Add(new JsonConfigurationSource { Path = "appsettings.json", ReloadOnChange = true })                 .Build();         }         public static AppsettingsHelper Instance         {             get             {                 if (instance == null)                 {                     lock (locker)                     {                         if (instance == null) instance = new AppsettingsHelper();                     }                 }                 return instance;             }         }           /// <summary>         /// 根据索引获取配置项value值         /// </summary>         /// <param name="indexPath"></param>         /// <returns></returns>         public string GetConfigByIndex(string indexPath)         {             return Configuration[indexPath].ToString();//Configuration["MEASSettings:PrintName"];         }           /// <summary>         /// 根据节点获取配置文件对象实例         /// </summary>         /// <param name="className"></param>         /// <returns></returns>         public IConfiguration GetConfigObjs(string className)         {             //string aa = Configuration.GetSection("MEASSettings").Get<MEASSettings>().PrintName;             return Configuration.GetSection(className);//    MEASSettings bbbb = see.Get<MEASSettings>();         }           /// <summary>         /// 根据具体对象获取对象实例         /// </summary>         /// <typeparam name="T">对象类型</typeparam>         /// <param name="obj">实体对象</param>         /// <returns></returns>         public object GetConfigObjByEntity<T>(T obj)         {             string className = Type.GetType(obj.ToString()).Name;             return Configuration.GetSection(className).Get(Type.GetType(obj.ToString()));         }       } }

第五步：使用方式如下所示：

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//方式一 string aa = Configuration.GetSection("MEASSettings").Get<MEASSettings>().PrintName; MEASSettings aaa = Configuration.GetSection("MEASSettings").Get<MEASSettings>(); //方式二 string bb = ConfigHelper.Instance.GetConfigByIndex("MEASSettings:PrintName"); //方式三 IConfiguration cc = ConfigHelper.Instance.GetConfigObjs("MEASSettings"); MEASSettings ccc = cc.Get<MEASSettings>(); //方式四 MEASSettings set = new MEASSettings(); MEASSettings ddd = ConfigHelper.Instance.GetConfigObjByEntity<MEASSettings>(set) as MEASSettings; //方式五 MEASSettings temp = ConfigHelper.Instance.GetConfigObjByEntity<MEASSettings>(new MEASSettings()) as MEASSettings;

 方式二：

第一步，根据appsettings.json 文件创建对应的对象模型

注：选择对应的对象(选择单个对象时，只选择对应的中括号)==》下面是选择所有配置内容后自动生成对象模型

自动生成后需根据实际情况修改对应的实体类名称--修改名称略

对象如下所示：

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{   "Logging": {     "LogLevel": {       "Default": "Information",       "Microsoft": "Warning",       "Microsoft.Hosting.Lifetime": "Information"     }   },   "MEASSettings":   {     "PrintName": "wula",     "PrintNum": 12   },     "AllowedHosts": "*"   }   //对应实体如下所示： using System;   namespace Test {     public class AppSettings     {         public Logging Logging { get; set; }         public MEASSettings MEASSettings { get; set; }         public string AllowedHosts { get; set; }     }       public class Logging     {         public Loglevel LogLevel { get; set; }     }       public class Loglevel     {         public string Default { get; set; }         public string Microsoft { get; set; }         public string MicrosoftHostingLifetime { get; set; }     }       public class MEASSettings     {         public string PrintName { get; set; }         public int PrintNum { get; set; }     }   }

第二步：根据视图对象模型，通过IConfiguration获取整个对象模型的对象

//通过对象模型获取AppSettings对象集合
var setting = new AppSettings();
Configuration.Bind(setting);
//调用使用AppSettings对象属性
string printName=setting.MEASSettings.PrintName;

 //部分绑定

var measSettings = new MEASSettings();
Configuration.GetSection("measSettings").Bind(measSettings);

方式三：注册配置选项服务

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public void ConfigureServices(IServiceCollection services)        {            //注册配置选项服务            services.Configure<AppSettings>(Configuration);            //......       }    public void Configure(IApplicationBuilder app, IWebHostEnvironment env,IOptions<AppSettings> options)        {<br>　　　　　　　　//使用配置选项服务            string printName = options.Value.MEASSettings.PrintName;              if (env.IsDevelopment())            {                app.UseDeveloperExceptionPage();                app.UseSwagger();                app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "WebApplication1 v1"));            }              app.UseHttpsRedirection();              app.UseRouting();              app.UseAuthorization();              app.UseEndpoints(endpoints =>            {                endpoints.MapControllers();            });        }

 方式四：

//自定义读取配置文件 + 注册配置选项服务
//自定义配置，注册配置选项，读取时通过options方式读取
var config = new ConfigurationBuilder().AddJsonFile("appsettings.json").Build();
string printName2=config["MEASSettings:PrintName"];
services.Configure<AppSettings>(config);