Flyweigth 享元模式

Flyweigth 享元模式 - 图1
数据库连接池、线程池、字符串常量池（String）都是享元模式。从pool取对象而不是一直new。

interface Flyweigths{
    void print();
}
class FlyweigthPart implements Flyweigths{
    String str;
    public FlyweigthPart(String str) {
        this.str = str;
    }
    @Override
    public void print() {
        System.out.println("str"+str);
    }
}
class FlyweigthsPool{
    ArrayList<Flyweigths> flyweigthsList = new ArrayList<>();
    public FlyweigthsPool add(Flyweigths flyweigths){
        flyweigthsList.add(flyweigths);
        return this;
    }
    public Flyweigths get(String a){
        for(Flyweigths flyweigths:flyweigthsList){
            if(((FlyweigthPart)flyweigths).str.equals(a)){
                return flyweigths;
            }
        }
        return new FlyweigthPart(a);
    }
}