轉(zhuǎn)：http://www.runoob.com/design-pattern/filter-pattern.html

過濾器模式

過濾器模式（Filter Pattern）或標(biāo)準(zhǔn)模式（Criteria Pattern）是一種設(shè)計(jì)模式，這種模式允許開發(fā)人員使用不同的標(biāo)準(zhǔn)來過濾一組對(duì)象，通過邏輯運(yùn)算以解耦的方式把它們連接起來尸疆。這種類型的設(shè)計(jì)模式屬于結(jié)構(gòu)型模式搬设，它結(jié)合多個(gè)標(biāo)準(zhǔn)來獲得單一標(biāo)準(zhǔn)。

實(shí)現(xiàn)

我們將創(chuàng)建一個(gè)?Person?對(duì)象排拷、Criteria?接口和實(shí)現(xiàn)了該接口的實(shí)體類，來過濾?Person?對(duì)象的列表。CriteriaPatternDemo倔幼，我們的演示類使用?Criteria?對(duì)象，基于各種標(biāo)準(zhǔn)和它們的結(jié)合來過濾?Person?對(duì)象的列表爽待。

步驟 1

創(chuàng)建一個(gè)類损同，在該類上應(yīng)用標(biāo)準(zhǔn)。

Person.java

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;

? }? }

步驟 2

為標(biāo)準(zhǔn)（Criteria）創(chuàng)建一個(gè)接口堕伪。

Criteria.java

import java.util.List;

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

步驟 3

創(chuàng)建實(shí)現(xiàn)了?Criteria?接口的實(shí)體類揖庄。

CriteriaMale.java

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

public 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;

? }}

CriteriaFemale.java

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

public 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;

? }}

CriteriaSingle.java

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

public 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;

? }}

AndCriteria.java

import java.util.List;

public 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);

? }}

OrCriteria.java

import java.util.List;

public 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;

? }}

步驟4

使用不同的標(biāo)準(zhǔn)（Criteria）和它們的結(jié)合來過濾?Person?對(duì)象的列表。

CriteriaPatternDemo.java

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()? ? ? ? ? ? +" ]");

? ? ? }? }? ? ? }

步驟 5

執(zhí)行程序欠雌，輸出結(jié)果：

Males:

?Person : [ Name : Robert, Gender : Male, Marital Status : Single ]

Person : [ Name : John, Gender : Male, Marital Status : Married ]

Person : [ Name : Mike, Gender : Male, Marital Status : Single ]

Person : [ Name : Bobby, Gender : Male, Marital Status : Single ]

Females:

?Person : [ Name : Laura, Gender : Female, Marital Status : Married ]

Person : [ Name : Diana, Gender : Female, Marital Status : Single ]

Single Males:?

Person : [ Name : Robert, Gender : Male, Marital Status : Single ]

Person : [ Name : Mike, Gender : Male, Marital Status : Single ]

Person : [ Name : Bobby, Gender : Male, Marital Status : Single ]

Single Or Females:?

Person : [ Name : Robert, Gender : Male, Marital Status : Single ]

Person : [ Name : Diana, Gender : Female, Marital Status : Single ]

Person : [ Name : Mike, Gender : Male, Marital Status : Single ]

Person : [ Name : Bobby, Gender : Male, Marital Status : Single ]

Person : [ Name : Laura, Gender : Female, Marital Status : Married ]