享元模式
1.解决对象复用问题
2.不破坏原本类的封装
3.池化资源管理：避免对象重复创建和销毁（尤其是非托管资源）
4.字符串 内存分配使用是享元模式（排除部分分配）
代码实现：
namespace FlyWeightPattern
{
public interface ILetter
{
public string GetLetter();
}
class LetterA:ILetter
{
private string name = "A";
public LetterA()
{
Console.WriteLine($"Letter {name} has been Created");
}
public string GetLetter()
{
return name;
}
}
class LetterE:ILetter
{
private string name = "E";
public LetterE()
{
Console.WriteLine($"Letter {name} has been Created");
}
public string GetLetter()
{
return name;
}
}
class LetterN:ILetter
{
private string name = "N";
public LetterN()
{
Console.WriteLine($"Letter {name} has been Created");
}
public string GetLetter()
{
return name;
}
}
class LetterP:ILetter
{
private string name = "P";
public LetterP()
{
Console.WriteLine($"Letter {name} has been Created");
}
public string GetLetter()
{
return name;
}
}
class LetterR:ILetter
{
private string name = "R";
public LetterR()
{
Console.WriteLine($"Letter {name} has been Created");
}
public string GetLetter()
{
return name;
}
}
private string name = "T";
public LetterT()
{
Console.WriteLine($"Letter {name} has been Created");
}
public string GetLetter()
{
return name;
}
}
享元封装：
public class FlyWeight
{
private static Dictionary<LetterType, ILetter> _letterDictionary = new Dictionary<LetterType, ILetter>();
private static object _flyWeightLock = new object();
public static ILetter CreateWordPattern(LetterType letterType)
{
if (!_letterDictionary.ContainsKey(letterType))
{
lock (_flyWeightLock)
{
if (!_letterDictionary.ContainsKey(letterType))
{
switch (letterType)
{
case LetterType.A:
_letterDictionary.Add(letterType, new LetterA());
break;
case LetterType.P:
_letterDictionary.Add(letterType, new LetterP());
break;
case LetterType.T:
_letterDictionary.Add(letterType, new LetterT());
break;
case LetterType.E:
_letterDictionary.Add(letterType, new LetterE());
break;
case LetterType.R:
_letterDictionary.Add(letterType, new LetterR());
break;
case LetterType.N:
_letterDictionary.Add(letterType, new LetterN());
break;
default:
throw new ArgumentOutOfRangeException(nameof(letterType), letterType, null);
}
}
}
}
return _letterDictionary[letterType];
}
public enum LetterType
{
P,
A,
T,
E,
R,
N
}
}
代码调用：
class Program
{
static void Main(string[] args)
{
Task.Run(() =>
{
for (int i = 0; i < 3; i++)
{
ILetter letter_P = FlyWeight.CreateWordPattern(FlyWeight.LetterType.P);
ILetter letter_A = FlyWeight.CreateWordPattern(FlyWeight.LetterType.A);
ILetter letter_T = FlyWeight.CreateWordPattern(FlyWeight.LetterType.T);
ILetter letter_E = FlyWeight.CreateWordPattern(FlyWeight.LetterType.E);
ILetter letter_R = FlyWeight.CreateWordPattern(FlyWeight.LetterType.R);
ILetter letter_N = FlyWeight.CreateWordPattern(FlyWeight.LetterType.N);
Console.WriteLine(
$"{letter_P.GetLetter().ToUpper()}{letter_A.GetLetter().ToLower()}{letter_T.GetLetter().ToLower()}{letter_T.GetLetter().ToLower()}{letter_E.GetLetter().ToLower()}{letter_R.GetLetter().ToLower()}{letter_N.GetLetter().ToLower()}"
);
}
});
Console.ReadLine();
}
}
结果：
