JAVA得到2011.2月有多少天

package org.dudu;import java.util.Calendar;public class GetTime {public static void main(String args[]){Calendar   cal   =   Calendar.getInstance();     cal.set(Calendar.YEAR,2011);     cal.set(Calendar.MONTH,1);//2月     int   maxDate   =   cal.getActualMaximum(Calendar.DATE);  System.out.println(maxDate);}}