[大数据]设计模式之享元模式（Flyweight模式）

一、UML类图

二、代码示例

• Client:

public class Client {
    public static void main(String[] args) {
        FlyweightFactory factory = new FlyweightFactory();
        Flyweight flyweight = factory.getFlyweight("name");
    }
}

• FlyweightFactory:

public class FlyweightFactory {
    private Map<String, Flyweight> pool = new HashMap<>();

    public Flyweight getFlyweight(String name) {
        Flyweight flyweight = pool.get(name);
        if (flyweight == null) {
            flyweight = new ConcreteFlyweight();
            pool.put(name, flyweight);
        }
        return flyweight;
    }
}

• Flyweight:

public interface Flyweight {
    void operation();
}

• ConcreteFlyweight:

public class ConcreteFlyweight implements Flyweight{
    @Override
    public void operation() { }
}

三、角色介绍

• Client（客户端）:
  客户端角色，程序的调用者。
• FlyweightFactory（轻量级工厂）:
  该角色负责生成Flyweight角色。
• Flyweight（轻量级）:
  该角色表示会被共享的抽象角色。
• ConcreteFlyweight（具体轻量级）:
  该角色表示会被共享的具体角色。