Java设计模式之享元模式

/**
 * 用户类
 * @author 董秀才
 *
 */
public class User {
 private String username; // 用户名
 private String password; // 密码
 
 public User(String username,String password) {
  this.username = username;
  this.password = password;
 }

 public String getUsername() {
  return username;
 }

 public void setUsername(String username) {
  this.username = username;
 }

 public String getPassword() {
  return password;
 }

 public void setPassword(String password) {
  this.password = password;
 }
}

/**
 * 登陆者--抽象享元类
 * @author 董秀才
 *
 */
public abstract class Loginer {
 
 //登陆--享元类公共方法
 public abstract void login(User user);
 
}

/**
 * 具体享元类
 * @author 董秀才
 *
 */
public class ConcreteLoginer extends Loginer{

 // 登陆者凭证
 private String loginerKey = "";
 public ConcreteLoginer(String loginerKey) {
  this.loginerKey = loginerKey;
 }
 
 @Override
 public void login(User user) {
  System.out.println("登陆者凭证：" + this.loginerKey+",用户名：" + user.getUsername() + ",密码：" + user.getPassword());
 }
 
}　

/**
 * 享元工厂类
 * @author 董秀才
 *
 */
public class ConcreteLoginerFactory {
 
 // map充当对象享元池
 private static Map<String,ConcreteLoginer> loginerMap = new HashMap<String, ConcreteLoginer>();
 
 public static ConcreteLoginer getConcreteLoginer(String key) {
  // 从享元池中拿 登陆者对象
  ConcreteLoginer concreteLoginer = loginerMap.get(key);
  // 如果享元池中没有此对象 
  if(concreteLoginer == null) {
   // 创建对象
   concreteLoginer = new ConcreteLoginer(key);
   // 存到享元池中
   loginerMap.put(key, concreteLoginer);
  }
  // 返回对象
  return concreteLoginer;
 }
 
 
 // 返回享元池对象数量
 public static int getSize() {
  return loginerMap.size();
 }
}

/**
* 博客测试类
* @author 董秀才
*
*/
public class MainTest {

public static void main(String[] args) {
// 去工厂拿对象
ConcreteLoginer concreteLoginer_1 = ConcreteLoginerFactory.getConcreteLoginer("csdn");
concreteLoginer_1.login(new User("董秀才","123456"));

ConcreteLoginer concreteLoginer_2 = ConcreteLoginerFactory.getConcreteLoginer("csdn");
concreteLoginer_2.login(new User("董秀才","123456"));

ConcreteLoginer concreteLoginer_3 = ConcreteLoginerFactory.getConcreteLoginer("csdn");
concreteLoginer_3.login(new User("董秀才","123456"));

// 测试是否是同一个对象
System.out.println("是否是同一个对象：" + ((concreteLoginer_1==concreteLoginer_2)&&(concreteLoginer_2 == concreteLoginer_3)));


// 第二登陆者
ConcreteLoginer concreteLoginer_4 = ConcreteLoginerFactory.getConcreteLoginer("博客园");
concreteLoginer_4.login(new User("董才才","654321"));

ConcreteLoginer concreteLoginer_5 = ConcreteLoginerFactory.getConcreteLoginer("博客园");
concreteLoginer_5.login(new User("董才才","654321"));

ConcreteLoginer concreteLoginer_6 = ConcreteLoginerFactory.getConcreteLoginer("博客园");
concreteLoginer_6.login(new User("董才才","654321"));

System.out.println("是否是同一个对象：" + ((concreteLoginer_4==concreteLoginer_5)&&(concreteLoginer_5 == concreteLoginer_6)));
// 工厂类中享元池中对象数量
System.out.println("享元池size：" + ConcreteLoginerFactory.getSize());
}

}