.NET Core 3.x 控制台應用調用 IConfiguration 和 依賴注入

IConfiguration

IConfiguration有兩個包

Microsoft.Extensions.Configuration
Microsoft.Extensions.Configuration.Json

具體使用

先創建 appsettings.json，注意兩個選項

這個 Json 文件內容

{
  "RabbitMQ": {
    "HostName": "192.168.0.151",
    "Port": "5672",
    "Administrator": {
      "Username": "administrator",
      "Password": "123456"
    }
  }
}

然后是創建對象，兩種方法
方法一

private static IConfiguration _configuration = new ConfigurationBuilder().SetBasePath(Directory.GetCurrentDirectory()).AddJsonFile("appsettings.json").Build();

方法二

private static IConfiguration _configuration = new ConfigurationBuilder().AddJsonFile("appsettings.json").Build();

完整代碼

class Program
{
    private static IConfiguration _configuration = new ConfigurationBuilder().SetBasePath(Directory.GetCurrentDirectory()).AddJsonFile("appsettings.json").Build();

    static void Main(string[] args)
    {
        Console.WriteLine(Program._configuration["RabbitMQ:HostName"]);
    }
}

運行結果

依賴注入

添加一個包

Microsoft.Extensions.DependencyInjection

這個配置就很簡單了，根據ASP.NET Core的寫

IServiceCollection services = new ServiceCollection();

舉個例子，IConfiguration 的依賴注入

IServiceCollection services = new ServiceCollection();
services.AddSingleton<IConfiguration>(serviceProvider =>
{
    IConfigurationBuilder configurationBuilder = new ConfigurationBuilder();
    configurationBuilder.AddJsonFile("appsettings.json");
    return configurationBuilder.Build();
});

創建對象

IConfiguration configuration = services.BuildServiceProvider().GetService<IConfiguration>();
Console.WriteLine(configuration["RabbitMQ:HostName"]);

運行結果

配置普通類

這個就跟ASP.NET Core一樣了

比如我有一個Test類，你也可以先寫一個接口，再寫一個類

public class Test
{
    private readonly IConfiguration _configuration;

    public Test(IConfiguration configuration)
    {
        this._configuration = configuration;
    }

    public void Foo()
    {
        Console.WriteLine(this._configuration["RabbitMQ:HostName"]);
    }
}

配置只有一句

services.AddSingleton<Test>();

完整代碼

static void Main(string[] args)
{
    IServiceCollection services = new ServiceCollection();
    services.AddSingleton<IConfiguration>(serviceProvider =>
    {
        IConfigurationBuilder configurationBuilder = new ConfigurationBuilder();
        configurationBuilder.AddJsonFile("appsettings.json");
        return configurationBuilder.Build();
    });

    services.AddSingleton<Test>();
    Test t = services.BuildServiceProvider().GetService<Test>();
    t.Foo();
}

運行結果

如果需要在其它類中調用容器，只需要將IServiceProvider serviceProvider作為參數傳遞即可，或者作為靜態字段寫類里面，單例模式也行

還有一個坑

IServiceProvider serviceProvider應該在配置完服務后再使用services.BuildServiceProvider()賦值一次

當然，也可以用AutoFac，C# 自帶的容器也可以，使用方式基本一致

.NET Core 3.x 控制台應用調用 IConfiguration 和 依賴注入 結束