策略模式--List排序

需求：根据姓名进行排序，升序或者降序，如果名字一样，就按照id升序排序，用策略模式

步骤一: 定义一个Person对象

public class Person {
    private Integer id;
    private String name;

    public Person(Integer id, String name) {
        this.id = id;
        this.name = name;
    }
    @Override
    public String toString() {
        return "Person{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
   setters & getters...
}

步骤二: 定义一个排序的接口

public interface SortInterface {
    public void sort(List<Person> list);
}

步骤三: 定义两个策略，升序(UpNameSort)和降序(DownNameSort)

import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class UpNameSort implements SortInterface, Comparator<Person>{

    @Override
    public int compare(Person o1, Person o2) {
        int result = o1.getName().compareTo(o2.getName());
        if(result == 0) {
            return o1.getId() - o2.getId();
        }
        return result;
    }

    @Override
    public void sort(List<Person> list) {
        Collections.sort(list, this);
    }
}

import java.util.Collections;
import java.util.Comparator;
import java.util.List;

public class DownNameSort implements SortInterface, Comparator<Person>{

    @Override
    public void sort(List<Person> list) {
        Collections.sort(list, this);
    }

    @Override
    public int compare(Person o1, Person o2) {
        int result = o2.getName().compareTo(o1.getName());
        if(result == 0) {
            return o1.getId() - o2.getId();
        }
        return result;
    }
}

步骤四: 定义SortEnviroment

import java.util.List;

public class SortEnviroment {
    private SortInterface sortInterface;

    public SortEnviroment(SortInterface sortInterface) {
        this.sortInterface = sortInterface;
    }

    public SortEnviroment() {
    }

    public void setSortInterface(SortInterface sortInterface) {
        this.sortInterface = sortInterface;
    }

    public void sort(List<Person> list) {
        sortInterface.sort(list);
    }
}

步骤五：测试

import java.util.ArrayList;
import java.util.List;

public class SortTestMain {
    public static void main(String[] args) {
        Person p1 = new Person(1, "Java");
        Person p2 = new Person(2, "Java");
        Person p3 = new Person(4, "Hadoop");
        Person p4 = new Person(0, "Spark");
        Person p5 = new Person(6, "Storm");
        Person p6 = new Person(8, "Jvm");

        List<Person> sortList = new ArrayList<Person>();

        sortList.add(p1);
        sortList.add(p2);
        sortList.add(p3);
        sortList.add(p4);
        sortList.add(p5);
        sortList.add(p6);

        SortInterface up = new UpNameSort();
        SortEnviroment se = new SortEnviroment(up);

        se.sort(sortList);

        for(Person p : sortList) {
            System.out.println("name:" + p.getName() + "," + "id:" + p.getId());
        }

        System.out.println("--------------------------");

        SortInterface down = new DownNameSort();
        se.setSortInterface(down);
        down.sort(sortList);

        for(Person p : sortList) {
            System.out.println("name:" + p.getName() + "," + "id:" + p.getId());
        }

    }
}