Khởi tạo Ứng dụng

Program.cs vs Startup.cs

Minimal APIs (.NET 6+)

// Program.cs - Minimal APIs
var builder = WebApplication.CreateBuilder(args);

// Add services
builder.Services.AddDbContext<AppDbContext>();
builder.Services.AddControllers();
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

var app = builder.Build();

// Configure middleware pipeline
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseHttpsRedirection();
app.UseAuthorization();
app.MapControllers();

app.Run();

Startup.cs (Trước .NET 6)

// Startup.cs - Traditional pattern
public class Startup
{
    public IConfiguration Configuration { get; }
    
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }
    
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddDbContext<AppDbContext>();
        services.AddControllers();
    }
    
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        
        app.UseHttpsRedirection();
        app.UseRouting();
        app.UseAuthorization();
        
        app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllers();
        });
    }
}

// Program.cs
public class Program
{
    public static void Main(string[] args)
    {
        CreateHostBuilder(args).Build().Run();
    }
    
    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>();
            });
}

So sánh

Các phương thức mở rộng thường dùng

Service Registration

// Singleton - Một instance duy nhất cho toàn bộ lifetime của app
builder.Services.AddSingleton<IService, Service>();

// Scoped - Một instance per request
builder.Services.AddScoped<IService, Service>();

// Transient - Instance mới mỗi lần được yêu cầu
builder.Services.AddTransient<IService, Service>();

Middleware Registration

var app = builder.Build();

// Run - Kết thúc pipeline (không gọi next)
app.Run(async context => 
{
    await context.Response.WriteAsync("Hello");
});

// Use - Có thể gọi next middleware
app.Use(async (context, next) =>
{
    // Do something before
    await next();
    // Do something after
});

// Map - Route-based middleware
app.Map("/api", appBuilder =>
{
    appBuilder.UseRouting();
});

Environment-based Configuration

if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

if (app.Environment.IsProduction())
{
    app.UseExceptionHandler("/Error");
}