过滤器模式 -- 设计模式

过滤器模式（Filter Pattern）或标准模式（Criteria Pattern）是一种设计模式

思考: 其实是将组合型的过滤器和具体实现类型的过滤器进行抽象, 将不同类型的过滤器抽象出一个方法, 然后使用组合型的过滤器来组合, 最后达到应用多个过滤器过滤数据源的作用

package day0318.FilterPattern;


import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

public class CriteriaPatternDemo{

    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"));

        CriteriaSingle criteriaSingle = new CriteriaSingle();
        CriterialFemale criterialFemale = new CriterialFemale();
        CriterialMale criterialMale = new CriterialMale();

        List<Person> singleAndFemalePersons = new AndCriterial(criteriaSingle, criterialFemale).meetCriteria(persons);

        System.out.println("single female: ");
        System.out.println(singleAndFemalePersons);

        System.out.println("single male: ");
        System.out.println(new AndCriterial(criterialMale, criteriaSingle).meetCriteria(persons));

        System.out.println("female and male");
        System.out.println(new AndCriterial(criterialFemale, criterialMale).meetCriteria(persons));

    }
}

// 约束接口
interface Criteria {
    List<Person> meetCriteria(List<Person> persons);
}

class AndCriterial implements Criteria {

    Criteria criteria;
    Criteria otherCriteria;

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

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


class OrCriterial implements Criteria {

    Criteria criteria;
    Criteria otherCriteria;

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

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



class CriterialFemale implements Criteria {

    @Override
    public List<Person> meetCriteria(List<Person> persons){
        return persons.stream()
                .filter((p) -> p.getGender()
                        .equalsIgnoreCase("FEMALE")).collect(Collectors.toList());
    }
}
class CriterialMale implements Criteria {

    @Override
    public List<Person> meetCriteria(List<Person> persons){
        List<Person> ret = new ArrayList<>();
        persons.stream()
                .filter((p) -> p.getGender()
                                        .equalsIgnoreCase("MALE"))
                .forEach(p -> ret.add(p));
        return ret;
    }
}

class CriteriaSingle implements Criteria {

    @Override
    public List<Person> meetCriteria(List<Person> persons) {
        List<Person> singlePersons = new ArrayList<Person>();
        for (Person person : persons) {
            if(person.getMaterialStatus().equalsIgnoreCase("SINGLE")){
                singlePersons.add(person);
            }
        }
        return singlePersons;
    }
}


class Person {

    String name;
    String gender;
    String materialStatus;

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

    @Override
    public String toString(){
        return "Person{" +
                "name='" + name + '\'' +
                ", gender='" + gender + '\'' +
                ", materialStatus='" + materialStatus + '\'' +
                '}';
    }

    public String getName(){
        return name;
    }

    public void setName(String name){
        this.name = name;
    }

    public String getGender(){
        return gender;
    }

    public void setGender(String gender){
        this.gender = gender;
    }

    public String getMaterialStatus(){
        return materialStatus;
    }

    public void setMaterialStatus(String materialStatus){
        this.materialStatus = materialStatus;
    }
}