如何读取 .NET 6 控制台应用程序中的 appsettings.json？

Question

我尝试创建 .NET 6 控制台应用程序，但在读取 appsettings.json 文件时遇到问题。在网络应用程序中我可以使用这个......

var builder = WebApplication.CreateBuilder(args);

但我会在控制台应用程序中使用什么？尝试将其添加到 program.cs 时出现此错误。"The name 'WebApplication' does not exist in the current context"

Answer 1

将这两个 nuget 包添加到您的应用程序中

Microsoft.Extensions.Configuration

Microsoft.Extensions.Configuration.Json

然后就可以ConfigurationBuilder使用appsettings.json文件了

var configuration =  new ConfigurationBuilder()
     .AddJsonFile($"appsettings.json");
            
var config = configuration.Build();
var connectionString = config.GetConnectionString("ConnectionString");

从控制台应用程序中的 AppSettings 获取值

在.net core应用程序中添加AppSettings

Answer 2

链接到文档：https ://learn.microsoft.com/en-us/dotnet/core/extensions/configuration

需要 Nuget 包来执行此操作：

<PackageReference Include="Microsoft.Extensions.Configuration.Binder" Version="6.0.0" />
    <PackageReference Include="Microsoft.Extensions.Configuration.Json" Version="6.0.0" />
    <PackageReference Include="Microsoft.Extensions.Configuration.EnvironmentVariables" Version="6.0.0" />

使用 Microsoft.Extensions.Configuration；

    // Build a config object, using env vars and JSON providers.
    IConfiguration config = new ConfigurationBuilder()
        .AddJsonFile("appsettings.json")
        .AddEnvironmentVariables()
        .Build();
    
    // Get values from the config, given their key and their target type.
    Settings settings = config.GetRequiredSection("Settings").Get<Settings>();
    
    // Write the values to the console.
    Console.WriteLine($"KeyOne = {settings.KeyOne}");
    Console.WriteLine($"KeyTwo = {settings.KeyTwo}");
    Console.WriteLine($"KeyThree:Message = {settings.KeyThree.Message}");

// Application code which might rely on the config could start here.
// This will output the following:
//   KeyOne = 1
//   KeyTwo = True
//   KeyThree:Message = Oh, that's nice...

JSON 文件 (appsettings.json)

{
    "Settings": {
        "KeyOne": 1,
        "KeyTwo": true,
        "KeyThree": {
            "Message": "Oh, that's nice..."
        }
    }
}

UPD：我检查了该方法，它有效；我的代码：

// See https://aka.ms/new-console-template for more information

using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Configuration.Json;

Console.WriteLine("Hello, World!");
ConfigurationBuilder configurationBuilder = new ConfigurationBuilder();
IConfiguration c = configurationBuilder.AddJsonFile("appsettings.json").AddEnvironmentVariables().Build();
var k = c.GetRequiredSection("Settings").Get<Settings>().KeyOne;
var n = 1;

public class NestedSettings
{
    public string Message { get; set; } = null!;
}
public class Settings
{
    public int KeyOne { get; set; }
    public bool KeyTwo { get; set; }
    public NestedSettings KeyThree { get; set; } = null!;
}

Answer 3

使用 .NET 6 控制台应用程序，尝试：

using IHost host = Host.CreateDefaultBuilder(args).Build();

IConfiguration config = host.Services.GetRequiredService<IConfiguration>();

string con= config.GetValue<string>("ConnectionStrings:conn1");
//OR
string connectionString = config["ConnectionStrings:conn1"];

Console.WriteLine($"Hello, World! {connectionString}");

appsettings.json（属性）：（CopyToOutputDirectory = 始终）：

"ConnectionStrings": {
    "conn1": "Server=localhost;Database=MyDatabase;Trusted_Connection=True", 
  }

Answer 4

在控制台应用程序中，我添加了appsettings.json，像user secrets这样，您也可能有一个开发 json 文件。

internal class Program
{
    internal static IConfigurationRoot Configuration;

    public static void Main()
        => new Program().MainAsync().GetAwaiter().GetResult();

    private async Task MainAsync()
    {
        var configurationBuilder = new ConfigurationBuilder();
        configurationBuilder.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true);
        configurationBuilder.AddUserSecrets(typeof(Program).GetTypeInfo().Assembly, optional: false);
        Configuration = configurationBuilder.Build();

        ...
    }
}

然后在任何类的控制台应用程序的其他地方，您都可以像这样简单地调用它

var someSetting = Program.Configuration["SomeSetting"];

如果您想要一个强类型类，请参阅此答案.net core Console applicationstrongly typed Configuration on SO