Extract Method方法
将函数中过长的代码提炼出来,然后组织在一起并独立到一个新的独立方法中,并让方法名称解释该方法的用途.该方法最好之处是有效的减少了方法中的代码.实例代码如下: 1 private string myName; 2 public void printPeople( int Age) 3 { 4 printFamily(); 5 // 
无数代码 // 6 7 // 打印个人信息 8 Console.WriteLine( " Name: " + myName); 9 Console.WriteLine( " Age: " + Age); 10 }
重构后的代码如下: 无数代码 // 6 7 // 打印个人信息 8 Console.WriteLine( " Name: " + myName); 9 Console.WriteLine( " Age: " + Age); 10 } 1 private string myName; 2 public void printPeople( int Age) 3 { 4 printFamily(); 5 // 无数代码 // 6 printMyInfo(Age); 7 } 8 9 void printMyInfo( int Age) 10 { 11 Console.WriteLine( " Name: " + myName); 12 Console.WriteLine( " Age: " + Age); 13 }
为什么要这样重构?当一个函数很大的时候,第一对代码的修改起来非常的不方便.第二,会对你读代码有障碍,试想一下当你看到一个很多行代码的方法,你还有心情看下去吗?第三,方法与方法之间的复用性会非常的好,方法的重写也会更容易些.那么我们应该怎么做呢?看第一个例子:无局部变量的方法提炼. 无数代码 // 6 printMyInfo(Age); 7 } 8 9 void printMyInfo( int Age) 10 { 11 Console.WriteLine( " Name: " + myName); 12 Console.WriteLine( " Age: " + Age); 13 } 1 void printOwing() 2 { 3 ArrayList al = myOrders.GetOrderList(); 4 double outstanding = 0.0 ; 5 6 // 打印头部信息 7 Console.WriteLine( " ***************** " ); 8 Console.WriteLine( " **Customer Owes** " ); 9 Console.WriteLine( " ***************** " ); 10 11 // 计算 12 foreach (Object o in al) 13 { 14 Order each = (Order)o; 15 outstanding += each.Amount; 16 } 17 18 // 打印具体信息 19 Console.WriteLine( " Name: " + myName); 20 Console.WriteLine( " Age: " + age); 21 }
好了我们开始先提最简单的部分.提出后的代码如下: 1 void printOwing() 2 { 3 ArrayList al = myOrders.GetOrderList(); 4 double outstanding = 0.0 ; 5 6 printBanner(); 7 8 // 计算 9 foreach (Object o in al) 10 { 11 Order each = (Order)o; 12 outstanding += each.Amount; 13 } 14 15 // 打印具体信息 16 Console.WriteLine( " Name: " + myName); 17 Console.WriteLine( " Age: " + age); 18 } 19 20 void printBanner() 21 { 22 // 打印头部信息 23 Console.WriteLine( " ***************** " ); 24 Console.WriteLine( " **Customer Owes** " ); 25 Console.WriteLine( " ***************** " ); 26 }
最简单的提炼方法结束了.下来我们看有局部变量的方法提炼.就拿上面的的代码开刀. 1 void printOwing() 2 { 3 ArrayList al = myOrders.GetOrderList(); 4 double outstanding = 0.0 ; 5 6 printBanner(); 7 8 // 计算 9 foreach (Object o in al) 10 { 11 Order each = (Order)o; 12 outstanding += each.Amount; 13 } 14 15 printInfo(outstanding); 16 } 17 18 void printBanner() 19 { 20 // 打印头部信息 21 Console.WriteLine( " ***************** " ); 22 Console.WriteLine( " **Customer Owes** " ); 23 Console.WriteLine( " ***************** " ); 24 } 25 26 void printInfo( double OutStanding) 27 { 28 // 打印具体信息 29 Console.WriteLine( " Name: " + myName); 30 Console.WriteLine( " Age: " + age); 31 }
我们再来看下对局部变量再赋值方法的提炼.继续拿上面代码开刀. 1 void printOwing() 2 { 3 double outstanding = GetOutStanding(); 4 5 printBanner(); 6 7 printInfo(outstanding); 8 } 9 10 void printBanner() 11 { 12 // 打印头部信息 13 Console.WriteLine( " ***************** " ); 14 Console.WriteLine( " **Customer Owes** " ); 15 Console.WriteLine( " ***************** " ); 16 } 17 18 void printInfo( double OutStanding) 19 { 20 // 打印具体信息 21 Console.WriteLine( " Name: " + myName); 22 Console.WriteLine( " Age: " + age); 23 } 24 25 double GetOutStanding() 26 { 27 ArrayList al = myOrders.GetOrderList(); 28 double outstanding = 0.0 ; 29 // 计算 30 foreach (Object o in al) 31 { 32 Order each = (Order)o; 33 outstanding += each.Amount; 34 } 35 return outstanding 36 }
Extract Method方法讲解玩了.有人会问为什么要这样写?这样写的好处我没有看到啊.那么现在有个这样的需求,我要设置outstanding的初始值,那么我们只要修改GetOutStanding方法,代码如下: 1 double GetOutStanding( double previousAmount) 2 { 3 ArrayList al = myOrders.GetOrderList(); 4 double outstanding = previousAmount; 5 // 计算 6 foreach (Object o in al) 7 { 8 Order each = (Order)o; 9 outstanding += each.Amount; 10 } 11 return outstanding 12 }
主要方法修改如下: 1 void printOwing() 2 { 3 double outstanding = GetOutStanding( 500.5 ); 4 5 printBanner(); 6 7 printInfo(outstanding); 8 }