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这篇文章主要介绍了Java中过滤器模式有什么用,具有一定借鉴价值,感兴趣的朋友可以参考下,希望大家阅读完这篇文章之后大有收获,下面让小编带着大家一起了解一下。
实现
我们将创建一个 Person 对象、Criteria 接口和实现了该接口的实体类,来过滤 Person 对象的列表。CriteriaPatternDemo,我们的演示类使用 Criteria 对象,基于各种标准和它们的结合来过滤 Person 对象的列表。
步骤 1
创建一个类,在该类上应用标准。
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; } }
步骤 2
为标准(Criteria)创建一个接口。
Criteria.java import java.util.List; public interface Criteria { public ListmeetCriteria(Listpersons); }
步骤 3
创建实现了 Criteria 接口的实体类。
CriteriaMale.java import java.util.ArrayList; import java.util.List; public class CriteriaMale implements Criteria { @Override public ListmeetCriteria(Listpersons) { ListmalePersons = new ArrayList(); 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 ListmeetCriteria(Listpersons) { ListfemalePersons = new ArrayList(); 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 ListmeetCriteria(Listpersons) { ListsinglePersons = new ArrayList(); 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 ListmeetCriteria(Listpersons) { ListfirstCriteriaPersons = 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 ListmeetCriteria(Listpersons) { ListfirstCriteriaItems = criteria.meetCriteria(persons); ListotherCriteriaItems = otherCriteria.meetCriteria(persons); for (Person person : otherCriteriaItems) { if(!firstCriteriaItems.contains(person)){ firstCriteriaItems.add(person); } } return firstCriteriaItems; } }
步骤4
使用不同的标准(Criteria)和它们的结合来过滤 Person 对象的列表。
CriteriaPatternDemo.java import java.util.ArrayList; import java.util.List; public class CriteriaPatternDemo { public static void main(String[] args) { Listpersons = new ArrayList(); 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(Listpersons){ for (Person person : persons) { System.out.println("Person : [ Name : " + person.getName() +", Gender : " + person.getGender() +", Marital Status : " + person.getMaritalStatus() +" ]"); } } }
步骤 5
执行程序,输出结果:
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 ]
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