java 获取本周，本月，本年 的第一天和最后一天

package z_test;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Hello {

/**
* @param args
*/
public static void main(String[] args) {
//格式化字符串
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
Calendar c = Calendar.getInstance();

c.set(Calendar.DAY_OF_WEEK, 2);                //本周的第一天，写1获取到的是周日，2获取到的是周一
System.out.println("本周的周一：" + sdf.format(c.getTime()));

c = Calendar.getInstance();
c.set(Calendar.DAY_OF_WEEK, 7);                //程序里一周的最后一天是周六，不符合中国人习惯，所以+1
c.add(c.DATE, 1);
System.out.println("本周的周日：" + sdf.format(c.getTime()));

c = Calendar.getInstance();
c.set(Calendar.DAY_OF_MONTH, 1);            //获取本月第一天
System.out.println("本月的第一天：" + sdf.format(c.getTime()));

c = Calendar.getInstance();
c.add(Calendar.MONTH, 1);                    //获取本月最后一天
c.set(Calendar.DAY_OF_MONTH, 1);
c.add(Calendar.DAY_OF_MONTH, -1);
System.out.println("本月的最后一天：" + sdf.format(c.getTime()));

c = Calendar.getInstance();
c.set(Calendar.DAY_OF_YEAR, 1);                //获取本年第一天
System.out.println("本年的第一天：" + sdf.format(c.getTime()));

c = Calendar.getInstance();
c.set(Calendar.DAY_OF_YEAR, 1);                //获取本年最后一天
c.set(Calendar.YEAR, 1);
c.add(Calendar.DAY_OF_YEAR, -1);
System.out.println("本年的最后一天：" + sdf.format(c.getTime()));
}
}