设计模式之过滤器模式

过滤器见名知意，就是过滤一些你不想看到的东西，



package com.lyc.design;

import java.util.ArrayList;
import java.util.List;

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"));

Criteria male = new CriteriaMale();
Criteria female = new CriteriaFemale();
Criteria single = new CriteriaSingle();
Criteria singleMale = new AndCriteria(single, male);
Criteria singleOrFemale = new OrCriteria(single, female);

System.out.println("Males: ");
printPersons(male.meetCriteria(persons));

System.out.println("\nFemales: ");
printPersons(female.meetCriteria(persons));

System.out.println("\nSingle Males: ");
printPersons(singleMale.meetCriteria(persons));

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() + " ]");
}
}
}

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;
}
}

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

class CriteriaMale implements Criteria {

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

class CriteriaFemale implements Criteria {

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

class CriteriaSingle implements Criteria {

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

class AndCriteria implements Criteria {

private Criteria criteria;
private 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);
}
}

class OrCriteria implements Criteria {

private Criteria criteria;
private 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);

for (Person person : otherCriteriaItems) {
if (!firstCriteriaItems.contains(person)) {
firstCriteriaItems.add(person);
}
}
return firstCriteriaItems;
}
}