java日期格式处理及月份第一天和最后一天

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

public class HandleDateUtil {

//日期格式化
private static SimpleDateFormat simpleFormate = new SimpleDateFormat(" yyyy-MM-dd ");

/**
*
* @description: 按日期格式返回月份第一天.
* @author: liuxmi
* @Date:Sep 9, 2009
* @return
* @return:String
*/
public static String getFirstDayOfMonth() {
Calendar calendar = new GregorianCalendar();
calendar.set(Calendar.DATE, 1);
System.out.println(simpleFormate.format(calendar.getTime()));
return simpleFormate.format(calendar.getTime());
}

/**
*
* @description: 按日期格式返回月份最后天.
* @author: liuxmi
* @Date:Sep 9, 2009
* @return
* @return:String
*/
public static String getLastDayOfMonth() {
Calendar calendar = new GregorianCalendar();
calendar.set(Calendar.DATE, 1);
calendar.roll(Calendar.DATE, -1);
System.out.println(simpleFormate.format(calendar.getTime()));
return simpleFormate.format(calendar.getTime());
}
/**

* 返回当前格式日期

*/
public static String getDateFormat(Date date) {
return simpleFormate.format(date);
}
/**

*返回特定格式的日期

*/
public static String getDateFormat(Date date,SimpleDateFormat dateFormat) {
return dateFormat.format(date);
}
/**
*
* @description: 返回指定年月的月的第一天.
* @author: liuxmi
* @Date:Sep 11, 2009
* @param year
* @param month
* @return
* @return:String
*/
public static String getFirstDayOfMonth(Integer year,Integer month){
Calendar calendar = new GregorianCalendar();
if(year == null){
year = calendar.get(Calendar.YEAR);
}
if(month == null){
month = calendar.get(Calendar.MONTH);
}
calendar.set(year, month, 1);
System.out.println(simpleFormate.format(calendar.getTime()));
return simpleFormate.format(calendar.getTime());
}
/**
*
* @description: 返回指定年月的月的最后一天.
* @author: liuxmi
* @Date:Sep 11, 2009
* @param year
* @param month
* @return
* @return:String
*/
public static String getLastDayOfMonth(Integer year,Integer month) {
Calendar calendar = new GregorianCalendar();
if(year == null){
year = calendar.get(Calendar.YEAR);
}
if(month == null){
month = calendar.get(Calendar.MONTH);
}
calendar.set(year, month, 1);
calendar.roll(Calendar.DATE, -1);
System.out.println(simpleFormate.format(calendar.getTime()));
return simpleFormate.format(calendar.getTime());
}

}