在ASP.NET中使用三层架构（也称为MVC或MVVM模式）来管理数据库，可以提高代码的可维护性、可扩展性和可重用性。以下是如何在ASP.NET中使用三层架构来管理数据库的步骤：
数据访问层负责与数据库进行交互。你可以使用Entity Framework、Dapper等ORM工具来简化数据库操作。
创建模型类：
public class Product { public int Id { get; set; } public string Name { get; set; } public decimal Price { get; set; } } 创建DbContext类：
public class ProductDbContext : DbContext { public DbSet<Product> Products { get; set; } protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) { optionsBuilder.UseSqlServer("YourConnectionStringHere"); } } 创建数据访问类：
public class ProductRepository : IProductRepository { private readonly ProductDbContext _context; public ProductRepository(ProductDbContext context) { _context = context; } public IEnumerable<Product> GetAllProducts() { return _context.Products.ToList(); } public Product GetProductById(int id) { return _context.Products.Find(id); } public void AddProduct(Product product) { _context.Products.Add(product); _context.SaveChanges(); } public void UpdateProduct(Product product) { _context.Products.Attach(product); _context.Entry(product).State = EntityState.Modified; _context.SaveChanges(); } public void DeleteProduct(int id) { var product = _context.Products.Find(id); if (product != null) { _context.Products.Remove(product); _context.SaveChanges(); } } } 业务逻辑层负责处理业务规则和逻辑。
public class ProductService : IProductService { private readonly IProductRepository _productRepository; public ProductService(IProductRepository productRepository) { _productRepository = productRepository; } public IEnumerable<Product> GetAllProducts() { return _productRepository.GetAllProducts(); } public Product GetProductById(int id) { return _productRepository.GetProductById(id); } public void AddProduct(Product product) { _productRepository.AddProduct(product); } public void UpdateProduct(Product product) { _productRepository.UpdateProduct(product); } public void DeleteProduct(int id) { _productRepository.DeleteProduct(id); } } 表示层负责与用户交互，通常是一个Web应用程序。
public class ProductController : Controller { private readonly IProductService _productService; public ProductController(IProductService productService) { _productService = productService; } public ActionResult Index() { var products = _productService.GetAllProducts(); return View(products); } public ActionResult Details(int id) { var product = _productService.GetProductById(id); if (product == null) { return HttpNotFound(); } return View(product); } [HttpPost] public ActionResult Create(Product product) { if (ModelState.IsValid) { _productService.AddProduct(product); return RedirectToAction("Index"); } return View(product); } [HttpPost] public ActionResult Edit(Product product) { if (ModelState.IsValid) { _productService.UpdateProduct(product); return RedirectToAction("Index"); } return View(product); } [HttpPost, ActionName("Delete")] public ActionResult DeleteConfirmed(int id) { var product = _productService.GetProductById(id); _productService.DeleteProduct(id); return RedirectToAction("Index"); } } 使用依赖注入来管理对象的生命周期和依赖关系。
public void ConfigureServices(IServiceCollection services) { services.AddDbContext<ProductDbContext>(options => options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection"))); services.AddScoped<IProductRepository, ProductRepository>(); services.AddScoped<IProductService, ProductService>(); services.AddControllersWithViews(); } 创建相应的视图文件来显示和编辑数据。
@model IEnumerable<Product> <h1>Products</h1> <table> <thead> <tr> <th>Id</th> <th>Name</th> <th>Price</th> <th></th> </tr> </thead> <tbody> @foreach (var item in Model) { <tr> <td>@item.Id</td> <td>@item.Name</td> <td>@item.Price</td> <td> <a asp-action="Edit" asp-route-id="@item.Id">Edit</a> | <a asp-action="Details" asp-route-id="@item.Id">Details</a> | <a asp-action="Delete" asp-route-id="@item.Id">Delete</a> </td> </tr> } </tbody> </table> <a asp-action="Create">Add New Product</a> @model Product <h1>@Model.Name</h1> <p>Price: @Model.Price</p> <a asp-action="Edit" asp-route-id="@Model.Id">Edit</a> | <a asp-action="Delete" asp-route-id="@Model.Id">Delete</a> | <a asp-action="Index">Back to List</a> @model Product <h1>Add New Product</h1> @using (Html.BeginForm()) { @Html.ValidationSummary(true, "", new { @class = "text-danger" }) <div class="form-group"> <label asp-for="Name" class="control-label"></label> <input asp-for="Name" class="form-control" /> <span asp-validation-for="Name" class="text-danger"></span> </div> <div class="form-group"> <label asp-for="Price" class="control-label"></label> <input asp-for="Price" class="form-control" /> <span asp-validation-for="Price" class="text-danger"></span> </div> <div class="form-group"> <input type="submit" value="Create" class="btn btn-primary" /> </div> } @section Scripts { @{await Html.RenderPartialAsync("_ValidationScriptsPartial");} } 通过以上步骤，你可以在ASP.NET中使用三层架构来管理数据库。这种架构有助于将不同的关注点分离，使代码更加清晰和易于维护。
