步步为营 .NET 代码重构学习笔记七

一、Extract Class（提炼类）

动机（Motivation）

一个class应该是一个清楚的抽象（abstract），处理一些明确的责任。但在实际工作中，class会不断成长扩展。这个class会变得过份复杂，很快，class就会变成一团乱麻。

示例

public class Person
{
    private string _name;
    private string _officeAreaCode;
    private string _officeNumber;
 
    public string Name
    {
        get { return _name; }
        set { _name = value; }
    }
 
    public string OfficeAreaCode
    {
        get { return _officeAreaCode; }
        set { _officeAreaCode = value; }
    }
 
    public string OfficeNumber
    {
        get { return _officeNumber; }
        set { _officeNumber = value; }
    }
 
    public string TelephoneNumber
    {
        get { return "(" + _officeAreaCode + ")" + _officeNumber; }
    }
}

改为

public class Person
  {
      private string _name;
      private Telephone _telephoneNumber;
 
      public Telephone TelephoneNumber
      {
          get { return _telephoneNumber; }
          set { _telephoneNumber = value; }
      }
 
      public string Name
      {
          get { return _name; }
          set { _name = value; }
      }
 
      public string TemphoneNumber
      {
          get { return _telephoneNumber.TelephoneNumber; }
      }
 
  }
  public class Telephone
  {
      private string _officeAreaCode;
      private string _officeNumber;
      public string OfficeAreaCode
      {
          get { return _officeAreaCode; }
          set { _officeAreaCode = value; }
      }
 
      public string OfficeNumber
      {
          get { return _officeNumber; }
          set { _officeNumber = value; }
      }
 
      public string TelephoneNumber
      {
          get { return "(" + _officeAreaCode + ")" + _officeNumber; }
      }
  }

二、Inline Class（将类内联化）

动机（Motivation）

一个class不再承担足够责任、不再有单独存在的理由，将class的所有特性搬移到另一个class中，然后移除原class。

示例

public class User
{
    private int _ID;
    private string _name;
 
    public int ID
    {
        get { return _ID; }
        set { _ID = value; }
    }
 
    public string Name
    {
        get { return _name; }
        set { _name = value; }
    }
 
 
}
public class UserInfo
{
    private int _ID;
    private string _Age;
 
    public string ID
    {
        get { return _ID; }
        set { _ID = value; }
    }
 
    public string Age
    {
        get { return _Age; }
        set { _Age = value; }
    }
}

改为

public class User
{
    private int _ID;
    private string _name;
    private string _Age;
 
    public int ID
    {
        get { return _ID; }
        set { _ID = value; }
    }
 
    public string Name
    {
        get { return _name; }
        set { _name = value; }
    }
 
    public string Age
    {
        get { return _Age; }
        set { _Age = value; }
    }
}

三、Hide Delegate（隐藏[委托关系]）

动机（Motivation）

[封装]即使不是对象的最关键特征，也是最关键特征之一。[封装]意味每个对象都应该尽可能少了解系统的其它部分。如此一来，一旦发生变化，需要了解这变化的对象就会比较少，这会使谈化比较容易进行。

示例

public class User
{
    private int _ID;
    private string _name;
    private Department _depart;
 
    public int ID
    {
        get { return _ID; }
        set { _ID = value; }
    }
 
    public string Name
    {
        get { return _name; }
        set { _name = value; }
    }
 
    public Department Depart
    {
        get { return _depart; }
        set { _depart = value; }
    }
 
}
 
public class Department
{
    private string _departName;
    private User _manager;
 
    public string DepartName
    {
        get { return _departName; }
        set { _departName = value; }
    }
 
    public User Manager
    {
        get { return _manager; }
        set { _manager = value; }
    }
}

改为

public class User
  {
      private int _ID;
      private string _name;
      private Department _depart;
 
      public int ID
      {
          get { return _ID; }
          set { _ID = value; }
      }
 
      public string Name
      {
          get { return _name; }
          set { _name = value; }
      }
 
      public Department Depart
      {
          get { return _depart; }
          set { _depart = value; }
      }
 
      public string DepartmentManager
      {
          get { return _depart.Manager; }
      }
  }
 
  public class Department
  {
      private string _departName;
      private User _manager;
 
      public string DepartName
      {
          get { return _departName; }
          set { _departName = value; }
      }
 
      public User Manager
      {
          get { return _manager; }
          set { _manager = value; }
      }
  }

这样取部门管理者就更直接，更方便，适合于少量使用。

但如果有大量的方法都用到了DepartmentManager里，我们就要去掉中间人了。

四、Remove Middle Man（移除中间人）

动机（Motivation）

大量重复的代码是万恶之源。这些重复性代码应该抽出来放进同一个函数中。

示例

public class User
{
    private int _ID;
    private string _name;
    private Department _depart;
 
    public int ID
    {
        get { return _ID; }
        set { _ID = value; }
    }
 
    public string Name
    {
        get { return _name; }
        set { _name = value; }
    }
 
    public Department Depart
    {
        get { return _depart; }
        set { _depart = value; }
    }
 
    public string DepartmentManager
    {
        get { return _depart.Manager; }
    }
}
 
public class Department
{
    private string _departName;
    private User _manager;
 
    public string DepartName
    {
        get { return _departName; }
        set { _departName = value; }
    }
 
    public User Manager
    {
        get { return _manager; }
        set { _manager = value; }
    }
}

改为

public class User
{
    private int _ID;
    private string _name;
    private Department _depart;
 
    public int ID
    {
        get { return _ID; }
        set { _ID = value; }
    }
 
    public string Name
    {
        get { return _name; }
        set { _name = value; }
    }
 
    public Department Depart
    {
        get { return _depart; }
        set { _depart = value; }
    }
 
}
 
public class Department
{
    private string _departName;
    private User _manager;
 
    public string DepartName
    {
        get { return _departName; }
        set { _departName = value; }
    }
 
    public User Manager
    {
        get { return _manager; }
        set { _manager = value; }
    }
}