public static BaseWord CreateWord(WordType wordType)
{
if (!FlyweightFactoryDic.ContainsKey(wordType)) //为了优化性能，避免对象已经被初始化后还要等待锁
{
lock (FlyweightFactoryLock) //C#语法糖 Monitor.Enter 保证方法体只有一个线程进去
{
if (!FlyweightFactoryDic.ContainsKey(wordType))
{
BaseWord baseWord = null;
switch (wordType)
{
case WordType.E:
baseWord = new E();
break;
case WordType.L:
baseWord = new L();
break;
case WordType.V:
baseWord = new V();
break;
default:
throw new Exception("Wrong word TYpe");
}
FlyweightFactoryDic.Add(wordType, baseWord);
}
}
}
return(FlyweightFactoryDic[wordType]);
//方法一
//BaseWord baseWord = null;
//switch (wordType)
//{
// case WordType.E:
// baseWord = new E();
// break;
// case WordType.L:
// baseWord = new L();
// break;
// case WordType.V:
// baseWord = new V();
// break;
// default:
// throw new Exception("Wrong word TYpe");
//}
//return baseWord;
}
public static void Show()
{
///做到对象复用，又不破坏封装
///1、统一入口，控制全局的东西
///2、添加重用逻辑--静态字典缓存起来
///
{
//for (int i = 0; i < 5; i++)
//{
// Task.Run(() =>
// {
// BaseWord e1 = FlyweightFactory.CreateWord(WordType.E);
// BaseWord e = FlyweightFactory.CreateWord(WordType.E);
// BaseWord l = FlyweightFactory.CreateWord(WordType.L);
// BaseWord v = FlyweightFactory.CreateWord(WordType.V);
// Console.WriteLine($"{e1.Get()}{l.Get()}{v.Get()}{e.Get()}");
// // Thread.Sleep(1000);
// });
//}
}
///享元模式：为了解决对象的复用问题，提供第三方的管理，能完成对象的复用
///1、还可以自行实例化对象，不像单例模式强制保证
///2、享元工厂可以初始化保存多个对象——其他的地方调用都可以找我拿（修改个状态）--用完之后再放回来（状态改回来）
///--避免重复创建和销毁对象，尤其对于非托管资源--》这个就是我们池化资源管理
{
BaseWord e1 = FlyweightFactory.CreateWord(WordType.E);
E e2 = new E();
E e3 = new E();
Console.WriteLine(object.ReferenceEquals(e1, e2));
Console.WriteLine(object.ReferenceEquals(e1, e3));
Console.WriteLine(object.ReferenceEquals(e3, e2));
//打印结果：false false false
}
//C#内存分配问题
{
string a = "Hello";
string b = "Hello";
Console.WriteLine(object.ReferenceEquals(a, b)); //true
Console.WriteLine(object.ReferenceEquals(a, new OtherClass().C)); //true
// string 在内存分配时使用享元模式
//只要是统一进程，分配 Hello都是同一个内存地址 所以以上答案都是true
string d = string.Format("He{0}", "llo");
string part = "llo";
string e = "He" + part;
Console.WriteLine(object.ReferenceEquals(a, d)); //false
Console.WriteLine(object.ReferenceEquals(a, e)); //false
Console.WriteLine(object.ReferenceEquals(d, e)); //false
//以上这两个是部分分配空间，虽然最终结果是Hello，没法重用
Console.WriteLine("**************");
string f = "He" + "llo";
string h = $"He{part}";
Console.WriteLine(object.ReferenceEquals(a, f)); //true
Console.WriteLine(object.ReferenceEquals(a, h)); //false
Console.WriteLine(object.ReferenceEquals(h, f)); //false
//编译器的优化问题 a="Hello" 等同于 f = "He" + "llo"; 反编译器可以查看 +号不存在，直接是 f="Hello "
}
{
//BaseWord e1 = FlyweightFactory.CreateWord(WordType.E);
//BaseWord e = FlyweightFactory.CreateWord(WordType.E);
//BaseWord l = FlyweightFactory.CreateWord(WordType.L);
//BaseWord v = FlyweightFactory.CreateWord(WordType.V);
//Console.WriteLine($"{e1.Get()}{l.Get()}{v.Get()}{e.Get()}");
}
}
