.NET Core类库中读取配置文件

public static class ConfigHelper
{
    private static IConfiguration _configuration;

    static ConfigHelper()
    {
        //在当前目录或者根目录中寻找appsettings.json文件
        var fileName = "appsettings.json";

        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}";
        }

        var builder = new ConfigurationBuilder()
            .AddJsonFile(filePath, false, true);

        _configuration = builder.Build();
    }

    public static string GetSectionValue(string key)
    {
        return _configuration.GetSection(key).Value;
    }
}

{
  "key": "value"
}

public class ConfigHelperTest
{
    [Fact]
    public void GetSectionValueTest()
    {
        var value = ConfigHelper.GetSectionValue("key");
        Assert.Equal(value, "value");
    }
}