使用策略模式让集合自定义排序
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package com.zj.exercise2;import java.util.List;/** * 功能:抽象策略角色 * @author zhengjiong * time:2011-9-16 00:02:12 */public interface Strategy{public void sort(List<Person> list);}?
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import java.util.Collections;import java.util.Comparator;import java.util.List;/** * 功能:定义一个具体的策略角色(Strategy),也是一个比较器(Comparator),按username的升序排列 * @author zhengjiong * time:2011-9-16 上午12:02:56 */public class StrategyByUsernameimplements Strategy, Comparator{@Overridepublic void sort(List<Person> list){Collections.sort(list, this);}/** * 按照username的升序排列,如果username一样则按照id的升序排列 */@Overridepublic int compare(Object o1, Object o2){Person p1 = (Person)o1;Person p2 = (Person)o2;//如果姓名一样则按照id升序排列if(p1.getUsername().equals(p2.getUsername())){return p1.getId() - p2.getId();}//按照username升序排列return p1.getUsername().compareTo(p2.getUsername());}}?
import java.util.List;/** * 功能:策略模式的环境角色 * @author zhengjiong * time:2011-9-16 上午01:08:40 */public class Environment{private Strategy strategy;public Environment(Strategy strategy){this.strategy = strategy;}public void sort(List list){strategy.sort(list);}public void setStrategy(Strategy strategy){this.strategy = strategy;}public Strategy getStrategy(){return strategy;}}?package com.zj.exercise2;
import java.util.Iterator;import java.util.LinkedList;import java.util.List;/** * 功能:使用策略模式让集合排序 * @author zhengjiong * time:2011-9-16 上午01:10:49 */public class Client{public static void main(String[] args){Person p1 = new Person(1, "e", 16);Person p2 = new Person(5, "a", 15);Person p3 = new Person(4, "c", 20);Person p4 = new Person(2, "b", 23);Person p5 = new Person(3, "f", 18);Person p6 = new Person(6, "a", 18);Person p7 = new Person(8, "y", 20);Person p8 = new Person(7, "x", 16);Person p9 = new Person(9, "b", 25);Person p10 = new Person(10, "h", 19);List<Person> list = new LinkedList<Person>();list.add(p1);list.add(p2);list.add(p3);list.add(p4);list.add(p5);list.add(p6);list.add(p7);list.add(p8);list.add(p9);list.add(p10);for(Iterator i = list.iterator(); i.hasNext();){Person person = (Person)i.next();System.out.println(person);}System.out.println();System.out.println("------------id升序------------");//实例化具体的策略模式StrategyById sbi = new StrategyById();//实例化环境角色,使用id升序排列Environment env = new Environment(sbi);env.sort(list);for(Iterator i = list.iterator(); i.hasNext();){Person person = (Person)i.next();System.out.println(person);}System.out.println();System.out.println("------------id降序------------");//实例化具体的策略模式StrategyByIdDESC sbidesc = new StrategyByIdDESC();//设置为降序模式env.setStrategy(sbidesc);env.sort(list);for(Iterator i = list.iterator(); i.hasNext();){Person person = (Person)i.next();System.out.println(person);}System.out.println();System.out.println("------------username升序,如果名字一样按照id升序排列------------");//实例化具体的策略模式StrategyByUsername sbu = new StrategyByUsername();//设置为降序模式env.setStrategy(sbu);env.sort(list);for(Iterator i = list.iterator(); i.hasNext();){Person person = (Person)i.next();System.out.println(person);}System.out.println();System.out.println("------------username降序,如果名字一样按照id升序排列------------");//实例化具体的策略模式StratigyByUsernameDESC sbdesc = new StratigyByUsernameDESC();//设置为降序模式env.setStrategy(sbdesc);env.sort(list);for(Iterator i = list.iterator(); i.hasNext();){Person person = (Person)i.next();System.out.println(person);}}}?