【设计模式】享元模式

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享元模式

定义：运用共享技术减少创建对象的数量，从而减少内存的占用，提升性能。

public interface Employee{
	public void report();
}

public class Manager implements Employee{
	private String department;  // 部门
	private String noteContent;  // 汇报内容

	public Manager(String department){
		this.department = department;
	}

	// getter & setter

	@Override
	public void report(){
		System.out.println(noteContent);
	}
}

创建工厂类（共享技术），批量创建所需对象（减少了对象的创建）:

public class ManagerFactory {
	private static final Map<String, Employee> EMPLOYEE_MAP = new HashMap<>();
	public static Employee getManager(String department) {
		Manager manager = (Manager) EMPLOYEE_MAP.get(department);
		if (manager == null) {
			manager = new Manager();
			manager.setNoteContent(department + "部门经理来此汇报工作");
			EMPLOYEE_MAP.put(department, manager);
		}
		return manager;
	}
}

至此，减少了对象的创建，后续获取Manager对象可直接从EMPLOYEE_MAP集合中获取，减少开销。