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");
         }
     }
 }