java 过滤器模式(Filter/Criteria Pattern)详细介绍

时间:2022-10-25 17:29:33

java 过滤器模式(Filter/Criteria Pattern)

过滤器模式(Filter Pattern)或标准模式(Criteria Pattern)是一种设计模式,这种模式允许开发人员使用不同的标准来过滤一组对象,通过逻辑运算以解耦的方式把它们连接起来。这种类型的设计模式属于结构型模式,它结合多个标准来获得单一标准。

 过滤器模式(Filter Pattern)或标准模式(Criteria Pattern)是一种设计模式,这种模式允许开发人员使用不同的标准来过滤一组对象,通过逻辑运算以解耦的方式把它们连接起来。这种类型的设计模式属于结构型模式,它结合多个标准来获得单一标准。

 

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。

java 过滤器模式(Filter/Criteria Pattern)详细介绍

 步骤 1

创建一个类,在该类上应用标准。

Person.java

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
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

?
1
2
3
4
5
6
import java.util.List;
 
public interface Criteria {
  public List<Person> meetCriteria(List<Person> persons);
}

步骤 3

创建实现了 Criteria 接口的实体类。

CriteriaMale.java

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
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

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
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

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
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

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
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

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
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

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
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()
      +" ]");
   }
  }  
}

步骤 5

验证输出。

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
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 ]

感谢阅读,希望能帮助到大家,谢谢大家对本站的支持!