过滤器模式 rust和java的实现

文章目录

过滤器模式
- - 实现
过滤器模式
- - 实现
  - java
  - rust
  - java
  - rust
- rust代码仓库

过滤器模式

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 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。
我们制作一个Person实体类，Criteria为标准条件，CriteriaMale等为实现的具体判断器，是需要为person类使用meetCriteria方法便可以进行不同条件的判断。
过滤器模式的 UML 图

过滤器模式

实现

java

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 List<Person> meetCriteria(List<Person> persons);
}

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 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) {
      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
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 ]

rust

由于时间关系，并没有实现or条件，大家有兴趣可以自行补充

// 设置人类实体类
#[derive(Clone)]
struct Person{
    name:String,
    gender:String,
    marital_status:String
}
impl Person {
 
    fn get_gender(&self)->&str {
        self.gender.as_ref()
    }
    fn get_marital_status(&self)->&str {
        self.marital_status.as_ref()
    }
}
// 设置过滤标准特征
trait Criteria {
  fn meet_criteria(&self,persons:Vec<Person>)->Vec<Person>; 
}
// 设置男性
struct CriteriaMale{}
// 重写男性评判标准
impl   Criteria for CriteriaMale {
    fn meet_criteria(&self,persons:Vec<Person>)->Vec<Person>{
        persons.into_iter().filter(|x| x.get_gender().eq_ignore_ascii_case("MALE")).collect()
    }
}
// 设置女性
struct CriteriaFemale{}
// 设置女性标准
impl   Criteria for CriteriaFemale{
    fn meet_criteria(&self,persons:Vec<Person>)->Vec<Person>{
        persons.into_iter().filter(|x| x.get_gender().eq_ignore_ascii_case("FEMALE")).collect()
    }
}
// 设置单身标准
struct CriteriaSingle{}

impl   Criteria for CriteriaSingle{
    fn meet_criteria(&self,persons:Vec<Person>)->Vec<Person>{
        persons.into_iter().filter(|x| x.get_marital_status().eq_ignore_ascii_case("SINGLE")).collect()
    }
}
// 设置and标准，求交集
struct AndCriteria  {
    criteria:Box<dyn Criteria>,
    other_criteria:Box<dyn Criteria>
}

impl Criteria for AndCriteria {
    fn meet_criteria(&self,persons:Vec<Person>)->Vec<Person> {
        self.other_criteria.meet_criteria(self.criteria.meet_criteria(persons))
    }
}
// struct OrCriteria {
//     criteria:Box<dyn Criteria>,
//     other_criteria:Box<dyn Criteria>
// }

// impl Criteria for OrCriteria{
//     fn meet_criteria(&self,persons:Vec<Person>)->Vec<Person> {
//         let mut first_criteria_items = self.criteria.meet_criteria(persons);
//         let other_criteria_items = self.other_criteria.meet_criteria(persons);
//         for o in other_criteria_items  {
//             if !other_criteria_items.contains(&o) {
//                 first_criteria_items.push(o);
//             }
//         }
//         first_criteria_items

//     }
// }
fn print_persons(persons:Vec<Person>) {
    persons.into_iter().for_each(|x| println!("Person : [NAME: {},Gender : {} ,Maeital Status : {} ]",x.name,x.gender,x.marital_status));
}
fn main() {
    let mut persons=Vec::new();
    persons.push(Person{name:String::from("Robert"),gender:String::from("Male"),marital_status:String::from("Single")});
    persons.push(Person{name:String::from("John"),gender:String::from("Male"),marital_status:String::from("Married")});
    persons.push(Person{name:String::from("Laura"),gender:String::from("Female"),marital_status:String::from("Married")});
    persons.push(Person{name:String::from("Diana"),gender:String::from("Female"),marital_status:String::from("Single")});

    let male=Box::new(CriteriaMale{});
    let female=Box::new(CriteriaFemale{});
    let single_male=AndCriteria{criteria:Box::new(CriteriaSingle{}),other_criteria:Box::new(CriteriaMale{})};
    // let single_or_female=OrCriteria{criteria:Box::new(CriteriaMale{}),other_criteria:Box::new(CriteriaFemale{})};
    println!("男士");
    print_persons(male.meet_criteria(persons.clone()));
    println!("女士");
    print_persons(female.meet_criteria(persons.clone()));
    println!("单身男士");
    print_persons(single_male.meet_criteria(persons))


}