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

 1 //我的性格
 2 public class MyCharacter {
 3     private char mychar;
 4     
 5     public MyCharacter(char mychar) {
 6         this.mychar = mychar;
 7     }
 8     
 9     public void display() {
10         System.out.println(mychar);
11     }
12 }

我的性格的工厂

 1 import java.util.HashMap;
 2 import java.util.Map;
 3 
 4 //我的性格的工厂
 5 public class MyCharacterFactory {
 6     private Map<Character,MyCharacter> pool;
 7     
 8     public MyCharacterFactory() {
 9         pool = new HashMap<Character,MyCharacter>();
10     }
11     
12     public MyCharacter getMyCharacter(Character character) {
13         MyCharacter myChar = pool.get(character);
14         if(myChar == null) {
15             myChar = new MyCharacter(character);
16             pool.put(character, myChar);
17         }
18         return myChar;
19     }
20 }

测试

 1 public class MainClass {
 2 
 3     public static void main(String[] args) {
 4 //        MyCharacter myChar1 = new MyCharacter('a');
 5 //        MyCharacter myChar2 = new MyCharacter('b');
 6 //        MyCharacter myChar3 = new MyCharacter('a');
 7 //        MyCharacter myChar4 = new MyCharacter('d');
 8 //        
 9 //        myChar1.display();
10 //        myChar2.display();
11 //        myChar3.display();
12 //        myChar4.display();
13 //        
14 //        if(myChar1 == myChar3) {
15 //            System.out.println("true");
16 //        } else {
17 //            System.out.println("false");
18 //        }
19         //1.创建MyCharacter工厂
20         MyCharacterFactory factory = new MyCharacterFactory();
21         
22         //2.从工厂中取出相应的MyCharacter
23         MyCharacter myChar1 = factory.getMyCharacter('a');
24         MyCharacter myChar2 = factory.getMyCharacter('b');
25         MyCharacter myChar3 = factory.getMyCharacter('a');
26         MyCharacter myChar4 = factory.getMyCharacter('d');
27         
28         myChar1.display();
29         myChar2.display();
30         myChar3.display();
31         myChar4.display();
32         
33         if(myChar1 == myChar3) {
34             System.out.println("true");
35         } else {
36             System.out.println("false");
37         }
38     }
39 }

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

人

 1 public class Person {
 2     private String name;
 3     private int age;
 4     private String sex;
 5     
 6     public Person(String name, int age, String sex) {
 7         super();
 8         this.name = name;
 9         this.age = age;
10         this.sex = sex;
11     }
12     
13     public Person() {
14         
15     }
16     
17     public String getName() {
18         return name;
19     }
20     public void setName(String name) {
21         this.name = name;
22     }
23     public int getAge() {
24         return age;
25     }
26     public void setAge(int age) {
27         this.age = age;
28     }
29     public String getSex() {
30         return sex;
31     }
32     public void setSex(String sex) {
33         this.sex = sex;
34     }
35 }

老师

 1 public class Teacher extends Person {
 2     private String number;
 3     
 4     public String getNumber() {
 5         return number;
 6     }
 7 
 8     public void setNumber(String number) {
 9         this.number = number;
10     }
11 
12     public Teacher(String name, int age, String sex,String number) {
13         super(name, age, sex);
14         this.number = number;
15     }
16     
17     public Teacher() {
18         super();
19     }
20 }

老师工厂

 1 import java.util.HashMap;
 2 import java.util.Map;
 3 //老师工厂
 4 public class TeacherFactory {
 5     private Map<String,Teacher> pool;
 6     
 7     public TeacherFactory() {
 8         pool = new HashMap<String,Teacher>();
 9     }
10     
11     public Teacher getTeacher(String number) {
12         Teacher teacher = pool.get(number);
13         if(teacher == null) {
14             teacher = new Teacher();
15             teacher.setNumber(number);
16             pool.put(number, teacher);
17         }
18         return teacher;
19     }
20 }

测试方法

 1 public class MainClass {
 2     public static void main(String[] args) {
 3         TeacherFactory factory = new TeacherFactory();
 4         Teacher teacher1 = factory.getTeacher("0102034");
 5         Teacher teacher2 = factory.getTeacher("0102035");
 6         Teacher teacher3 = factory.getTeacher("0102034");
 7         Teacher teacher4 = factory.getTeacher("0102037");
 8         
 9         System.out.println(teacher1.getNumber());
10         System.out.println(teacher2.getNumber());
11         System.out.println(teacher3.getNumber());
12         System.out.println(teacher4.getNumber());
13         
14         if(teacher1 == teacher3) {
15             System.out.println("true");
16         } else {
17             System.out.println("false");
18         }
19     }
20 }