過濾器模式/標準模式

介紹

      允許開發人員使用不同的標準來過濾一組對象，通過邏輯運算以解耦的方式把它們連接起來。這種類型的設計模式屬於結構型模式，它結合多個標準來獲得單一標準。

UML

代碼實現 

public class FilterpatternDemo {
	public static void main(String[] args) {
		List<Person> persons = new ArrayList<Person>();
		persons.add(new Person("Robert", "Male", "Single"));
		persons.add(new Person("John", "Male", "Married"));
		persons.add(new Person("Laura", "Female", "Married"));
		persons.add(new Person("Diana", "Female", "Single"));
		persons.add(new Person("Mike", "Male", "Single"));
		persons.add(new Person("Bobby", "Male", "Single"));
		//選擇男性
		Criteria male = new CriteriaMale();
		//選擇女性
		Criteria female = new CriteriaFemale();
		//選擇單身
		Criteria single = new CriteriaSingle();
		System.out.println("Males: ");
		printPersons(male.meetCriteria(persons));
		System.out.println("\nFemales: ");
		printPersons(female.meetCriteria(persons));
		//過濾出男的 單身
		Criteria singleMale = new AndCriteria(single, male);
		System.out.println("\nSingle Males: ");
		printPersons(singleMale.meetCriteria(persons));
		//過濾出女的單身
		Criteria singleOrFemale = new OrCriteria(single, female);
		System.out.println("\nSingle Or Females: ");
		printPersons(singleOrFemale.meetCriteria(persons));
	}

	public static void printPersons(List<Person> persons) {
		for (Person person : persons) {
			System.out.println("Person : [ Name : " + person.getName() + ", Gender : " + person.getGender()
					+ ", Marital Status : " + person.getMaritalStatus() + " ]");
		}
	}
}

public interface Criteria {
	/**過濾*/
	List<Person> meetCriteria(List<Person> persons);
}

/**
 * 過濾出男性
 */
class CriteriaMale implements Criteria {
	@Override
	public List<Person> meetCriteria(List<Person> persons) {
		List<Person> malePersons = new ArrayList<>();
		for (Person person : persons) {
			if (person.getGender().equalsIgnoreCase("MALE")) {
				malePersons.add(person);
			}
		}
		return malePersons;
	}
}

/**
 * 過濾出女性
 */
class CriteriaFemale implements Criteria {
	@Override
	public List<Person> meetCriteria(List<Person> persons) {
		List<Person> femalePersons = new ArrayList<>();
		for (Person person : persons) {
			if (person.getGender().equalsIgnoreCase("FEMALE")) {
				femalePersons.add(person);
			}
		}
		return femalePersons;
	}
}

/**
 * 過濾出單身
 */
class CriteriaSingle implements Criteria {
	@Override
	public List<Person> meetCriteria(List<Person> persons) {
		List<Person> singlePersons = new ArrayList<>();
		for (Person person : persons) {
			if (person.getMaritalStatus().equalsIgnoreCase("SINGLE")) {
				singlePersons.add(person);
			}
		}
		return singlePersons;
	}
}

/**
 * 過濾器與過濾器之間的關係爲 and
 */
class AndCriteria implements Criteria {
	//第一次過濾
	private final Criteria criteria;
	//第二次過濾
	private final Criteria otherCriteria;

	public AndCriteria(Criteria criteria, Criteria otherCriteria) {
		this.criteria = criteria;
		this.otherCriteria = otherCriteria;
	}

	@Override
	public List<Person> meetCriteria(List<Person> persons) {
		List<Person> firstCriteriaPersons = criteria.meetCriteria(persons);
		return otherCriteria.meetCriteria(firstCriteriaPersons);
	}
}

/**
 * 過濾器與過濾器之間的關係爲 or
 */
class OrCriteria implements Criteria {
	private final Criteria criteria;
	private final Criteria otherCriteria;

	public OrCriteria(Criteria criteria, Criteria otherCriteria) {
		this.criteria = criteria;
		this.otherCriteria = otherCriteria;
	}

	@Override
	public List<Person> meetCriteria(List<Person> persons) {
		List<Person> firstCriteriaItems = criteria.meetCriteria(persons);
		List<Person> otherCriteriaItems = otherCriteria.meetCriteria(persons);
		//求並集
		firstCriteriaItems.addAll(otherCriteriaItems);
		return firstCriteriaItems;
	}
}

public class Person {
	private String name;
	private String gender;
	private String maritalStatus;

	public Person(String name, String gender, String maritalStatus) {
		this.name = name;
		this.gender = gender;
		this.maritalStatus = maritalStatus;
	}

	public String getName() {
		return name;
	}

	public String getGender() {
		return gender;
	}

	public String getMaritalStatus() {
		return maritalStatus;
	}
}