防止 class 方法一次执行多次

Question

我有一个 asp.net mvc 控制器，它在执行时调用服务中的一个方法 class 打开文件并开始将记录导入数据库。我想以某种方式限制此方法或 class，以便无法创建另一个实例并防止在完成运行之前再次调用该方法。我读过单例模式，但我不确定它是否可以实现，因为 class 是通过依赖注入实例化的。

依赖注入由 Autofac 处理

服务Class：

namespace Nop.Plugin.Misc.CAImport.Services
{    
    public class CAImportService: ICAImportService
    {
        #region Fields
        private IProductService _productService;
        private ICategoryService _categoryService;
        private IManufacturerService _manufacturerService;

        #endregion

        #region Constructor
        public CAImportService(IProductService productService, 
            ICategoryService categoryService,
            IManufacturerService manufacturerService)
        {
            this._productService = productService;
            this._categoryService = categoryService;
            this._manufacturerService = manufacturerService;
        }
        #endregion

        #region Methods
        /// <summary>
        /// Import products from tab delimited file
        /// </summary>
        /// <param name="fileName">String</param>
        public virtual void ImportProducts(string fileName, bool deleteProducts)
        {
            //Do stuff to import products

        }

        #endregion
    }
}

控制器Class:

namespace Nop.Plugin.Misc.CAImport.Controllers
{
    public class MiscCAImportController: BasePluginController
    {
        private ICAImportService _caImportService;

        public MiscCAImportController(ICAImportService caImportService)
        {
            this._caImportService = caImportService;
        }

        [AdminAuthorize]
        public ActionResult ImportProducts()
        {
            return View("~/plugins/misc.caimport/views/misccaimport/ImportProducts.cshtml");
        }

        [HttpPost]
        [AdminAuthorize]
        public ActionResult ImportProducts(ImportProductsModel model)
        {
            string fileName = Server.MapPath(model.Location);

            _caImportService.ImportProducts(fileName, model.DeleteProducts);                    

            return View("~/plugins/misc.caimport/views/misccaimport/ImportProducts.cshtml", model);
        }
    }
}

Answer 1

下面的代码在您的服务中添加了一个锁，以防止其他线程同时执行封闭的语句。

public class CAImportService: ICAImportService
{

    // OTHER METHODS AND SECTIONS REMOVED FOR CLARITY

    // Define static object for the lock
    public static readonly object _lock = new object();

    /// <summary>
    /// Import products from tab delimited file
    /// </summary>
    /// <param name="fileName">String</param>
    public virtual void ImportProducts(string fileName, bool deleteProducts)
    {
        lock (_lock)
        {
            //Do stuff to import products
        }
    }
}

防止 class 方法一次执行多次

Preventing a class method from executing more than once at a time

c#

asp.net-mvc

singleton

dependency-injection