10享元模式Flyweight

一、什么是享元模式

　　Flyweight模式也叫享元模式，是构造型模式之 一，它通过与其他类似对象共享数据来减小内存 占用。

二、享元模式的结构

三、享元模式的角色和职责

　　抽象享元角色： 所有具体享元类的父类，规定一些需要实现的公共接口。

　　具体享元角色：     抽象享元角色的具体实现类，并实现了抽象享元角色规定的方法。

　　 享元工厂角色：    负责创建和管理享元角色。

没用享元模式前

//我的性格
public class MyCharacter {
    private char mychar;
    
    public MyCharacter(char mychar) {
        this.mychar = mychar;
    }
    
    public void display() {
        System.out.println(mychar);
    }
}

我的性格的工厂

import java.util.HashMap;
import java.util.Map;

//我的性格的工厂
public class MyCharacterFactory {
    private Map<Character,MyCharacter> pool;
    
    public MyCharacterFactory() {
        pool = new HashMap<Character,MyCharacter>();
    }
    
    public MyCharacter getMyCharacter(Character character) {
        MyCharacter myChar = pool.get(character);
        if(myChar == null) {
            myChar = new MyCharacter(character);
            pool.put(character, myChar);
        }
        return myChar;
    }
}

测试

public class MainClass {

    public static void main(String[] args) {
//        MyCharacter myChar1 = new MyCharacter('a');
//        MyCharacter myChar2 = new MyCharacter('b');
//        MyCharacter myChar3 = new MyCharacter('a');
//        MyCharacter myChar4 = new MyCharacter('d');
//        
//        myChar1.display();
//        myChar2.display();
//        myChar3.display();
//        myChar4.display();
//        
//        if(myChar1 == myChar3) {
//            System.out.println("true");
//        } else {
//            System.out.println("false");
//        }
        //1.创建MyCharacter工厂
        MyCharacterFactory factory = new MyCharacterFactory();
        
        //2.从工厂中取出相应的MyCharacter
        MyCharacter myChar1 = factory.getMyCharacter('a');
        MyCharacter myChar2 = factory.getMyCharacter('b');
        MyCharacter myChar3 = factory.getMyCharacter('a');
        MyCharacter myChar4 = factory.getMyCharacter('d');
        
        myChar1.display();
        myChar2.display();
        myChar3.display();
        myChar4.display();
        
        if(myChar1 == myChar3) {
            System.out.println("true");
        } else {
            System.out.println("false");
        }
    }
}

===============================================================

人

public class Person {
    private String name;
    private int age;
    private String sex;
    
    public Person(String name, int age, String sex) {
        super();
        this.name = name;
        this.age = age;
        this.sex = sex;
    }
    
    public Person() {
        
    }
    
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
}

老师

public class Teacher extends Person {
    private String number;
    
    public String getNumber() {
        return number;
    }

    public void setNumber(String number) {
        this.number = number;
    }

    public Teacher(String name, int age, String sex,String number) {
        super(name, age, sex);
        this.number = number;
    }
    
    public Teacher() {
        super();
    }
}

老师工厂

import java.util.HashMap;
import java.util.Map;
//老师工厂
public class TeacherFactory {
    private Map<String,Teacher> pool;
    
    public TeacherFactory() {
        pool = new HashMap<String,Teacher>();
    }
    
    public Teacher getTeacher(String number) {
        Teacher teacher = pool.get(number);
        if(teacher == null) {
            teacher = new Teacher();
            teacher.setNumber(number);
            pool.put(number, teacher);
        }
        return teacher;
    }
}

测试方法

public class MainClass {
    public static void main(String[] args) {
        TeacherFactory factory = new TeacherFactory();
        Teacher teacher1 = factory.getTeacher("0102034");
        Teacher teacher2 = factory.getTeacher("0102035");
        Teacher teacher3 = factory.getTeacher("0102034");
        Teacher teacher4 = factory.getTeacher("0102037");
        
        System.out.println(teacher1.getNumber());
        System.out.println(teacher2.getNumber());
        System.out.println(teacher3.getNumber());
        System.out.println(teacher4.getNumber());
        
        if(teacher1 == teacher3) {
            System.out.println("true");
        } else {
            System.out.println("false");
        }
    }
}