策略模式小练习

练习：

假如有若干个person对象保存在list对象之中，对它们分别用id，姓名，年龄进行排序（正序/倒序），如果年龄或者姓名重复，则按照id的升序进行排序。要求使用策略模式进行。

Person对象

public class Person {

private int id;
private String name;
private int age;

public Person(int id, String name, int age) {
this.id = id;
this.name = name;
this.age = age;
}

public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}

}

1、抽象策略类

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

2、具体实现类(按id倒序排，其它略)

public class IdDescStrategy implements Strategy, Comparator<Person> {

@Override
public void sort(List<Person> list) {
Collections.sort(list, this);
}
@Override
public int compare(Person p1, Person p2) {
return p2.getId() - p1.getId();
}

}

3、环境类

public class Environment {

private Strategy strategy ;

public Environment(Strategy strategy) {
this.strategy = strategy;
}

public void setStrategy(Strategy strategy) {
this.strategy = strategy;
}

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

}

4、客户端

public static void main(String[] args) {
IdDescStrategy iddesc = new IdDescStrategy();
Environment environment = new Environment(iddesc);
List<Person> list = new ArrayList<Person>();
Person p1 = new Person(1, "wangxiaoxiao", 10);
Person p2 = new Person(2, "zhangshan", 20);
Person p3 = new Person(3, "lisi", 30);
Person p4 = new Person(4, "wangwu", 40);
Person p5 = new Person(5, "wangke", 50);
list.add(p1);
list.add(p2);
list.add(p3);
list.add(p4);
list.add(p5);
environment.sort(list);

for(Person p : list){
System.out.println(p.getId()+", "+p.getName()+", "+p.getAge());
}

}