过滤器模式 rust和java的实现-编程知识

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 {@Overridepublic 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 {@Overridepublic 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 {@Overridepublic 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; }@Overridepublic 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; }@Overridepublic 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))}