为 ASP.NET Core （6.0）服务应用添加ApiKey验证支持

这个代码段演示了如何为一个ASP.NET Core项目中添加Apikey验证支持。

首先，通过下面的代码创建项目

dotnet new webapi -minimal -o yourwebapi

然后修改已经生成的 builder.Services.AddSwaggerGen 这个方法，以便在Swagger 的页面可以输入ApiKey进行调试。

builder.Services.AddSwaggerGen((options) =>
{
    options.AddSecurityDefinition("ApiKey", new OpenApiSecurityScheme
    {
        Type = SecuritySchemeType.ApiKey,
        In = ParameterLocation.Header,
        Name = "ApiKey"
    });

    options.AddSecurityRequirement(new OpenApiSecurityRequirement
    {
        {
            new OpenApiSecurityScheme
            {
                Reference = new OpenApiReference
                {
                    Type = ReferenceType.SecurityScheme,
                    Id = "ApiKey"
                }
            },
            new string[] {}
        }
    });
});

在 var app = builder.Build(); 这一行下方添加一个中间件，用来验证ApiKey。请注意，这里特意跳过了swagger目录。另外，这里的密钥校验是硬编码的，你可以修改成自己需要的方式。

app.Use(async (context, next) =>
{
    var found = context.Request.Headers.TryGetValue("ApiKey", out var key);

    if (context.Request.Path.StartsWithSegments("/swagger") || (found && key == "abc"))
    {
        await next(context);
    }
    else
    {
        context.Response.StatusCode = 401;
        await context.Response.WriteAsync("没有合法授权");
        return;
    }
});

通过 dotnet watch run 将应用运行起来，并且访问 /swagger/index.html 这个网页，可以看到当前API项目的所有方法，并且可以输入ApiKey

然后你就可以在swagger 中进行API 调用测试了，当然你也可以通过 postman 等工具来测试。这里就不展开了。

完整代码如下，请参考

using Microsoft.OpenApi.Models;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen((options) =>
{
    options.AddSecurityDefinition("ApiKey", new OpenApiSecurityScheme
    {
        Type = SecuritySchemeType.ApiKey,
        In = ParameterLocation.Header,
        Name = "ApiKey"
    });

    options.AddSecurityRequirement(new OpenApiSecurityRequirement
    {
        {
            new OpenApiSecurityScheme
            {
                Reference = new OpenApiReference
                {
                    Type = ReferenceType.SecurityScheme,
                    Id = "ApiKey"
                }
            },
            new string[] {}
        }
    });
});

var app = builder.Build();

app.Use(async (context, next) =>
{
    var found = context.Request.Headers.TryGetValue("ApiKey", out var key);

    if (context.Request.Path.StartsWithSegments("/swagger") || (found && key == "abc"))
    {
        await next(context);
    }
    else
    {
        context.Response.StatusCode = 401;
        await context.Response.WriteAsync("没有合法授权");
        return;
    }
});

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseHttpsRedirection();

var summaries = new[]
{
    "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
};

app.MapGet("/weatherforecast", () =>
{
    var forecast = Enumerable.Range(1, 5).Select(index =>
        new WeatherForecast
        (
            DateTime.Now.AddDays(index),
            Random.Shared.Next(-20, 55),
            summaries[Random.Shared.Next(summaries.Length)]
        ))
        .ToArray();
    return forecast;
})
.WithName("GetWeatherForecast");

app.Run();

record WeatherForecast(DateTime Date, int TemperatureC, string? Summary)
{
    public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
}