C# 事件(Event)定义及其使用

1.定义个委托和类

//委托
public delegate void ProductEventHandler(Product product);

/// <summary>
/// 产品
/// </summary>
public class Product
{
    public int Id { get; set; }
    public string Code { get; set; }
    public string Name { get; set; }
    private decimal price;

    public decimal Price
    {
        get { return price; }
        set
        {
            price = value;
            if(price > 10)
            {
                //事件触发
                ProductChanged.Invoke(this);
            }
        }
    }

    //事件
    public event ProductEventHandler ProductChanged;
  
    /// <summary>
    /// 模拟业务的异常记录方法
    /// </summary>
    /// <param name="product"></param>
    public void RecordException(Product product)
    {
        Console.WriteLine($"事件被触发,价格波动异常：{product.Price}");
    }
}

2.调用(通过属性值得变化去触发事件)

var product = new Product();
product.ProductChanged += product.RecordException;
while (true)
{
    Console.Write("请输入价格:");
    var num = Convert.ToDecimal(Console.ReadLine());
    product.Price = num;
}