原文：http://www.runoob.com/design-pattern/ 少許個人理解，如有錯誤請指出。歡迎一起討論。(本文基本摘抄)
定義： 過濾器模式（Filter Pattern）或標準模式（Criteria Pattern）是一種設(shè)計模式，這種模式允許開發(fā)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(shè)計模式屬于結(jié)構(gòu)型模式，它結(jié)合多個標準來獲得單一標準。（主要功能：過濾）
代碼實現(xiàn)： 我們將創(chuàng)建一個 Person 對象、Criteria 接口和實現(xiàn)了該接口的實體類，來過濾 Person 對象的列表。CriteriaPatternDemo，我們的演示類使用 Criteria 對象，基于各種標準和它們的結(jié)合來過濾 Person 對象的列表。
過濾器模式的 UML 圖 
步驟 1 創(chuàng)建一個類，在該類上應(yīng)用標準。 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 為標準（Criteria）創(chuàng)建一個接口。 Criteria.java
import java.util.List;public interface Criteria { public List<Person> meetCriteria(List<Person> persons);}步驟 3 創(chuàng)建實現(xiàn)了 Criteria 接口的實體類。 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 使用不同的標準（Criteria）和它們的結(jié)合來過濾 Person 對象的列表。 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 驗證輸出。
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 ]and過濾邏輯：先拿標準一過濾，得到過濾一次后的person列表，再繼續(xù)進行第二次過濾。 or過濾邏輯：先用標準一過濾得到person列表1，再用標準二過濾得到person列表2，再講列表取并集，如果列表1中含有列表二沒有的item，add到列表二，列表二是最終的并集。
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