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 pool; 7 8 public MyCharacterFactory() { 9 pool = new HashMap ();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MyCharacter23 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 pool; 6 7 public TeacherFactory() { 8 pool = new HashMap (); 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 }