java 对象排序，根据多个字段进行排序

package comparotor;

import java.sql.Date;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Random;

import org.apache.commons.beanutils.BeanComparator;
import org.apache.commons.collections.ComparatorUtils;
import org.apache.commons.collections.comparators.ComparableComparator;
import org.apache.commons.collections.comparators.ComparatorChain;

public class Comparotor
{
	public static void main(String[] args)
	{
		Comparator mycmp1 = ComparableComparator.getInstance ();  
		mycmp1 = ComparatorUtils. reversedComparator(mycmp1); //逆序  
		  
		Comparator mycmp2 = ComparableComparator.getInstance ();  
//		mycmp2 = ComparatorUtils. reversedComparator(mycmp2); //允许null  
		mycmp2 = ComparatorUtils. nullHighComparator(mycmp2); //允许null  
		  
		// 声明要排序的对象的属性，并指明所使用的排序规则，如果不指明，则用默认排序  
		ArrayList<Object> sortFields = new ArrayList<Object>();  
		sortFields.add( new BeanComparator("age" , mycmp1)); //主排序（第一排序）  
		sortFields.add( new BeanComparator("birthday" , mycmp2)); //次排序（第二排序）  
		  
		// 创建一个排序链  
		ComparatorChain multiSort = new ComparatorChain(sortFields);  
		List<User> users = initUsers();  
		// 开始真正的排序，按照先主，后副的规则  
		Collections.sort (users , multiSort);
		System.out.println(">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>");
		for(int i =0;i<10;i++){
			User user = users.get(i);
			System.out.println(user.getName()+"---"+user.getSex()+"---"+user.getAge()+"---"+user.getBirthday());
		}
	}

	private static List<User> initUsers(){
		List<User> list = new ArrayList<User>();
		for(Integer i =0;i<10;i++){
			Random rm = new Random();
			User user = new User();
			user.setName("user"+i);
			user.setAge(rm.nextInt(10));
			if(i%2==0){
				user.setSex("1");
			}else{
				user.setSex("0");
			}
			user.setBirthday(new Date(2014,11,21));
			if(i==5){
				user.setBirthday(new Date(2014,11,20));
				user.setSex(null);
			}
			System.out.println(user.getName()+"---"+user.getSex()+"---"+user.getAge()+"---"+user.getBirthday());
			list.add(user);
		}
		return list;
	}
}