C#简单笔记09:委托，事件

柔情只为你懂 2023-06-11 03:22 16阅读 0赞

# 委托 #

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2lzaGVuamlhbWluZw_size_16_color_FFFFFF_t_70][]

建议：有C基础的，不妨把委托当做函数指针

委托-菜鸟教程[https://www.runoob.com/csharp/csharp-delegate.html][https_www.runoob.com_csharp_csharp-delegate.html]

C\#教程-委托（微软文档）[https://docs.microsoft.com/zh-cn/dotnet/csharp/tour-of-csharp/delegates][https_docs.microsoft.com_zh-cn_dotnet_csharp_tour-of-csharp_delegates]

C\#指南-编程指南-委托（微软文档）[https://docs.microsoft.com/zh-cn/dotnet/csharp/programming-guide/delegates/][https_docs.microsoft.com_zh-cn_dotnet_csharp_programming-guide_delegates]

C\#指南-C\#概念-委托和事件（微软文档）[https://docs.microsoft.com/zh-cn/dotnet/csharp/delegates-overview][https_docs.microsoft.com_zh-cn_dotnet_csharp_delegates-overview]

***委托类型***表示对具有特定参数列表和返回类型的方法的引用。 通过委托，可以将方法视为可分配给变量并可作为参数传递的实体。 委托类似于其他一些语言中的函数指针概念，但与函数指针不同的是，委托不仅面向对象，还类型安全。

下面的示例声明并使用 `Function` 委托类型。

using System;
    delegate double Function(double x);
    class Multiplier
    {
        double factor;
        public Multiplier(double factor) 
        {
            this.factor = factor;
        }
        public double Multiply(double x) 
        {
            return x * factor;
        }
    }
    class DelegateExample
    {
        static double Square(double x) 
        {
            return x * x;
        }
        static double[] Apply(double[] a, Function f) 
        {
            double[] result = new double[a.Length];
            for (int i = 0; i < a.Length; i++) result[i] = f(a[i]);
            return result;
        }
        static void Main() 
        {
            double[] a = {0.0, 0.5, 1.0};
            double[] squares = Apply(a, Square);
            double[] sines = Apply(a, Math.Sin);
            Multiplier m = new Multiplier(2.0);
            double[] doubles =  Apply(a, m.Multiply);
        }
    }

以上示例来自微软文档[https://docs.microsoft.com/zh-cn/dotnet/csharp/tour-of-csharp/delegates][https_docs.microsoft.com_zh-cn_dotnet_csharp_tour-of-csharp_delegates]

## 以下通过委托回调方法 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2lzaGVuamlhbWluZw_size_16_color_FFFFFF_t_70 1][]

![20191204195008393.png][]

## 以下使用+绑定新委托 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2lzaGVuamlhbWluZw_size_16_color_FFFFFF_t_70 2][]

## 以下使用-号解绑委托 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2lzaGVuamlhbWluZw_size_16_color_FFFFFF_t_70 3][]

# 事件 #

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2lzaGVuamlhbWluZw_size_16_color_FFFFFF_t_70 4][]

事件-菜鸟教程[https://www.runoob.com/csharp/csharp-event.html][https_www.runoob.com_csharp_csharp-event.html]

## 通过事件使用委托 ##

*  **更好的封装保护数据**
 *  **event禁止委托直接赋值，防止原有委托被直接替换掉。必须使用+=，-=来绑定或解除绑定**
 *  **event禁止在类外部直接调用委托，使其只能在类内部调用委托。**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2lzaGVuamlhbWluZw_size_16_color_FFFFFF_t_70 5][]

![20191204221237353.png][]

# \*发现本讲座C\#部分不全,故下一章将学习黑马C\#系列讲座\* #

两个讲座有重复部分,只当复习了.....

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2lzaGVuamlhbWluZw_size_16_color_FFFFFF_t_70]: /images/20230531/bb32708f9a704ffab73600f3cd096c18.png
[https_www.runoob.com_csharp_csharp-delegate.html]: https://www.runoob.com/csharp/csharp-delegate.html
[https_docs.microsoft.com_zh-cn_dotnet_csharp_tour-of-csharp_delegates]: https://docs.microsoft.com/zh-cn/dotnet/csharp/tour-of-csharp/delegates
[https_docs.microsoft.com_zh-cn_dotnet_csharp_programming-guide_delegates]: https://docs.microsoft.com/zh-cn/dotnet/csharp/programming-guide/delegates/
[https_docs.microsoft.com_zh-cn_dotnet_csharp_delegates-overview]: https://docs.microsoft.com/zh-cn/dotnet/csharp/delegates-overview
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2lzaGVuamlhbWluZw_size_16_color_FFFFFF_t_70 1]: /images/20230531/3aa2caee7d9d4345a34fc68bc5d87eba.png
[20191204195008393.png]: /images/20230531/6dca9fb7473b4f66bb9c2b890ed5a322.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2lzaGVuamlhbWluZw_size_16_color_FFFFFF_t_70 2]: /images/20230531/deca17484d114fe78296b3ac37bd099f.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2lzaGVuamlhbWluZw_size_16_color_FFFFFF_t_70 3]: /images/20230531/096a61d2fa1444ae89b7ae16bff0b76d.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2lzaGVuamlhbWluZw_size_16_color_FFFFFF_t_70 4]: /images/20230531/2647eb268cc242aea20f73fc8a64499c.png
[https_www.runoob.com_csharp_csharp-event.html]: https://www.runoob.com/csharp/csharp-event.html
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2lzaGVuamlhbWluZw_size_16_color_FFFFFF_t_70 5]: /images/20230531/c979e0cac6b94c488622f57e9a985551.png
[20191204221237353.png]: /images/20230531/206540476acd45d1b5c33dce416f30a2.png