135 lines
3.3 KiB
Dart
135 lines
3.3 KiB
Dart
/**
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过滤器模式（Filter Pattern）
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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。
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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。
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*/
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main(List<String> args) {
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List<Person> persons = List<Person>();
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persons.add(Person("Robert", "Male", "Single"));
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persons.add(Person("John", "Male", "Married"));
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persons.add(Person("Laura", "Female", "Married"));
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persons.add(Person("Diana", "Female", "Single"));
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persons.add(Person("Mike", "Male", "Single"));
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persons.add(Person("Bobby", "Male", "Single"));
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Filter male = MaleFilter();
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Filter female = FemaleFilter();
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Filter single = SingleFilter();
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Filter singleMale = AndFilter(single, male);
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Filter singleOrFemale = OrFilter(single, female);
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print("Males: ");
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male.filter(persons).forEach((p) => print(p));
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print("\nFemales: ");
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female.filter(persons).forEach((p) => print(p));
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print("\nSingle Males: ");
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singleMale.filter(persons).forEach((p) => print(p));
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print("\nSingle Or Females: ");
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singleOrFemale.filter(persons).forEach((p) => print(p));
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}
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//////////////////////////////////////////////////////////////////
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///
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/// 创建一个类，在该类上应用过滤器
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///
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class Person {
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String name;
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String gender;
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String maritalStatus;
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Person(this.name, this.gender, this.maritalStatus);
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@override
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String toString() {
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return 'Person[name="$name", gender="$gender", maritalStatus="$maritalStatus"]';
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}
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}
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///
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/// 创建一个过滤器接口
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///
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abstract class Filter {
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List<Person> filter(List<Person> persons);
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}
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///
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/// 创建实现了 Filter 接口的实体类
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///
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class MaleFilter implements Filter {
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@override
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List<Person> filter(List<Person> persons) {
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List<Person> personList = List<Person>();
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for (Person person in persons) {
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if (person.gender.toUpperCase() == "MALE") {
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personList.add(person);
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}
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}
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return personList;
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}
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}
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class FemaleFilter implements Filter {
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@override
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List<Person> filter(List<Person> persons) {
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List<Person> personList = List<Person>();
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for (Person person in persons) {
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if (person.gender.toUpperCase() == "FEMALE") {
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personList.add(person);
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}
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}
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return personList;
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}
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}
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class SingleFilter implements Filter {
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@override
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List<Person> filter(List<Person> persons) {
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List<Person> personList = List<Person>();
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for (Person person in persons) {
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if (person.maritalStatus.toUpperCase() == "SINGLE") {
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personList.add(person);
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}
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}
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return personList;
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}
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}
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class AndFilter implements Filter {
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Filter _filter1;
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Filter _filter2;
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AndFilter(this._filter1, this._filter2);
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@override
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List<Person> filter(List<Person> persons) {
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List<Person> personList = _filter1.filter(persons);
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return _filter2.filter(personList);
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}
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}
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class OrFilter implements Filter {
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Filter _filter1;
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Filter _filter2;
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OrFilter(this._filter1, this._filter2);
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@override
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List<Person> filter(List<Person> persons) {
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List<Person> personList1 = _filter1.filter(persons);
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List<Person> personList2 = _filter1.filter(persons);
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for (Person person in personList2) {
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if (!personList1.contains(person)) {
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personList1.add(person);
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}
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}
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return personList1;
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}
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}
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