C#读取配置文件内容

1.读取appsettings.json

　　1)配置文件

{
  "Logging": {
    "LogLevel": {
      "Default": "Warning"
    }
  },
  "AllowedHosts": "*",
  "ConnectionStrings": {
    "test": "xxxxxxx"
  },
  "CustomSettings": {
    "test": "xxxxx"
  }
}

　　2）读取方法

public class ConfigHelper
    {
        private static IConfigurationRoot builder;
        static ConfigHelper()
        {
            builder = new ConfigurationBuilder()
                         .AddInMemoryCollection()
                         .SetBasePath(Directory.GetCurrentDirectory())
                         .AddJsonFile("appsettings.json", optional: true, reloadOnChange: false)
                         .Build();
        }

        public static string GetConnectionString(string connName) =>
            builder.GetConnectionString(connName);

        public static string GetCustomSettings(string keyName) =>
            builder.GetSection("CustomSettings")[keyName];
    }

若出现 "ConfigurationBuilder”未包含“SetBasePath”的定义"的错误,解决方法如下：
 
nuget 引用以下包
Microsoft.Extensions.Configuration
Microsoft.Extensions.Configuration.FileExtensions
Microsoft.Extensions.Configuration.Json
Microsoft.Extensions.Configuration.Abstractions

　　

　3）调用

string test1= ConfigHelper.GetCustomSettings("test")
string test2= ConfigHelper.GetConnectionString("test")

2.读取App.config文件中的appSettings信息

　　1）配置文件

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
    <startup> 
        <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.7.2" />
    </startup>
	<appSettings>
		<add key="test" value="xxxx" />
	</appSettings> 
</configuration>

　　2）读取方法

// 第一种
public static string GetAppsettings(string key) => ConfigurationManager.AppSettings[key];
GetAppsettings("test")
// 第二种
private static System.Configuration.AppSettingsReader reader = new System.Configuration.AppSettingsReader();
reader.GetValue("test", typeof(String)).ToString()