C#高级语法基础知识总结5——委托&事件

我就是我 2021-10-15 11:31 318阅读 0赞

**委托**

**Delegate void IntMethodInvoker(int x);**

**Delegate double IntMethodInvoker(long x,long y);**

委托的一种方式，把方法组合到一个数组中来使用，这样就可以在循环中调用不同的方法了。

核心语句**ProcessAndDisplayNumber(operations\[j\], 2.0);**

![ContractedBlock.gif][] ![ExpandedBlockStart.gif][] 数组委托

1 delegate double DoubleOp(double x);
     2 
     3 
     4             DoubleOp[] operations =
     5 
     6             {
     7 
     8                 MathOperations.MultiplyByTwo,
     9 
    10                 MathOperations.Square,
    11 
    12             };
    13 
    14             for (int j = 0; j < operations.Length; j++)
    15 
    16             {
    17 
    18                 Console.WriteLine("Using operations[{0}]:", j);
    19 
    20                 ProcessAndDisplayNumber(operations[j], 2.0);
    21 
    22                 ProcessAndDisplayNumber(operations[j], 7.94);
    23 
    24                 ProcessAndDisplayNumber(operations[j], 1.414);
    25 
    26                 Console.WriteLine();
    27 
    28             }
    29 
    30         static void ProcessAndDisplayNumber(DoubleOp action, double value)
    31 
    32         {
    33 
    34             double result = action(value);
    35 
    36             Console.WriteLine("Value is {0},result of operation is {1}", value, result);
    37 
    38         }
    39 
    40         class MathOperations
    41 
    42         {
    43 
    44             public static double MultiplyByTwo(double value)
    45 
    46             {
    47 
    48                 return value * 2;
    49 
    50             }
    51 
    52             public static double Square(double value)
    53 
    54             {
    55 
    56                 return value * value;
    57 
    58             }
    59 
    60         }

**Action<T>和Func<T>委托**

Action<in T>可调用一个参数的方法，Action<in T1,in T2>可调用带两个参数的方法

**冒泡排序法**实例，运用Func<T, T, bool>委托

核心语句：

**static public void Sort<T>(IList<T> sortArray, Func<T, T, bool> comparison)**

**CreatDelegate.BubbleSorter.Sort(emplayees, CreatDelegate.Employee.CompareSalary);**

代码：

![ContractedBlock.gif][] ![ExpandedBlockStart.gif][] 运用Func<T, T, bool>委托冒泡排序法

1             CreatDelegate.Employee[] emplayees =
      2 
      3             {
      4 
      5                 new CreatDelegate.Employee("苏国强",10000),
      6 
      7                 new CreatDelegate.Employee("盖茨",8000),
      8 
      9                 new CreatDelegate.Employee("乔布斯",9000),
     10 
     11                 new CreatDelegate.Employee("扎克伯格",7000),
     12 
     13             };
     14 
     15             CreatDelegate.BubbleSorter.Sort(emplayees, CreatDelegate.Employee.CompareSalary);
     16 
     17             foreach (var employee in emplayees)
     18 
     19             {
     20 
     21                 Console.WriteLine(employee);
     22 
     23             }
     24  
     25 
     26         public class BubbleSorter
     27 
     28         {
     29 
     30             //冒泡排序
     31 
     32             static public void Sort<T>(IList<T> sortArray, Func<T, T, bool> comparison)
     33 
     34             {
     35 
     36                 bool swapped = true;
     37 
     38                 do
     39 
     40                 {
     41 
     42                     swapped = false;
     43 
     44                     for (int j = 0; j < sortArray.Count - 1; j++)
     45 
     46                     {
     47 
     48                         if (comparison(sortArray[j + 1], sortArray[j]))
     49 
     50                         {
     51 
     52                             T temp = sortArray[j];
     53 
     54                             sortArray[j] = sortArray[j + 1];
     55 
     56                             sortArray[j + 1] = temp;
     57 
     58                             swapped = true;
     59 
     60                         }                    }
     61 
     62                 } while (swapped);
     63 
     64             }
     65 
     66         }
     67 
     68  
     69 
     70         public class Employee
     71 
     72         {
     73 
     74             public string Name { get; private set; }
     75 
     76             public decimal Salary { get; private set; }
     77 
     78             public Employee(string name, decimal salary)
     79 
     80             {
     81 
     82                 this.Name = name;
     83 
     84                 this.Salary = salary;
     85 
     86             }
     87 
     88  
     89 
     90             public override string ToString()
     91 
     92             {
     93 
     94                 return string.Format("{0},{1:C}", Name, Salary);
     95 
     96             }
     97 
     98  
     99 
    100             public static bool CompareSalary(Employee e1, Employee e2)
    101 
    102             {
    103 
    104                 return e1.Salary < e2.Salary;
    105 
    106             }
    107 
    108         }

**多播委托**

**            Action<double> operations1 = MathOperations.MultiplyByTwo;//返回值void**

**            operations1 += MathOperations.Square;**

或

**            Action<double> operations1 = MathOperations.MultiplyByTwo; //返回值void**

**            Action<double> operations2 = MathOperations.Square; //返回值void**

**            Action<double> operations3 = operations1 + operations2; //返回值void**

Delegate类定义**GetInvocationList()**方法，返回一个Delegate对象数组。

**Action d1=One;**

**D1+=two;**

**Delegate\[\] delegates=d1.GetInvocationList();**

**匿名委托**

匿名方法是用作委托的参数的一段代码

anonDel是这种委托类型的变量，**不是**把方法赋予这个变量，**而是**使用一段简单的代码：它前面是关键字delegate,后面是一个字符串参数。

string mid = "国";
    
                Func<string, string> anonDel = delegate(string param)
    
                {
    
                    param += mid;
    
                    param += "强";
    
                    return param;
    
                };
    
                Console.WriteLine(anonDel("苏"));

**Lambda表达式**

Console.WriteLine("Lambda表达式");
    
                string mid1 = "国";
    
                Func<string, string> anonDel1 = param=>
    
                {
    
                    param += mid1;
    
                    param += "强";
    
                    return param;
    
                };
    
                Console.WriteLine(anonDel1("苏"));

**多个参数的Lambda表达式**

1             Func<double, double, double> twwoParams = (x, y) => x * y;
     2 
     3             Console.WriteLine(twwoParams(3,4));
     4 
     5             //可为花括号中给变量添加参数类型
     6 
     7             Func<double, double, double> towParamWithTypes =
     8 
     9                 (double x, double y) => x * y;
    10 
    11             Console.WriteLine(towParamWithTypes(4, 2));

**事件**

![ContractedBlock.gif][] ![ExpandedBlockStart.gif][] 事件

1  
     2         #region 事件发布程序
     3 
     4         public class CarInfoEventArgs : EventArgs
     5 
     6         {
     7 
     8             public string Car { get; private set; }
     9 
    10             public CarInfoEventArgs(string car)
    11 
    12             {
    13 
    14                 this.Car = car;
    15 
    16             }
    17 
    18         }
    19 
    20 
    21         public class CarDealer
    22 
    23         {
    24 
    25             public event EventHandler<CarInfoEventArgs> NewCarInfo;//定义事件委托
    26 
    27  
    28 
    29             public void NewCar(string car)
    30 
    31             {
    32 
    33                 Console.WriteLine("CarDealer,新车{0}",car);
    34 
    35                 if(NewCarInfo!=null)
    36 
    37                 {
    38 
    39                     NewCarInfo(this,new CarInfoEventArgs(car));
    40 
    41                 }
    42 
    43             }
    44 
    45         }
    46 
    47         #endregion
    48 
    49         #region 事件侦听器
    50 
    51         public class Consumer
    52 
    53         {
    54 
    55             private string name;
    56 
    57             public Consumer(string name)
    58 
    59             {
    60 
    61                 this.name = name;
    62 
    63             }
    64 
    65             public void NewCarIsHere(object sender, CarInfoEventArgs e)
    66 
    67             {
    68 
    69                 Console.WriteLine("{0}:车{1}是新的", name, e.Car);
    70 
    71             }
    72 
    73         }
    74 
    75         #endregion
    76 
    77 
    78             Console.WriteLine("事件-----------");
    79 
    80             var dealer = new DelegateEvent.CarDealer();
    81 
    82             var Soar = new DelegateEvent.Consumer("苏国强");
    83 
    84             dealer.NewCarInfo += Soar.NewCarIsHere;
    85 
    86             dealer.NewCar("博兰基尼");
    87 
    88

**弱事件管理器**

转载于:https://www.cnblogs.com/suguoqiang/archive/2012/07/16/2594368.html

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