java的移位运算实例

public class StrToByte {
 /**
  * 将yyMMddhhmmss格式日期字符串转换成byte[] <br/>
  * 其中yy取最大为62即2000--2062
  * 
  * @author linfenliang
  * @date 2012-6-19
  * @version V1.0.0
  * @param dateStr
  *            :日期字符串
  * @return byte[]
  */
 public static byte[] strToByte(String dateStr) {
 byte[] timeByte = new byte[4];
 int[] tempTime = new int[6];
 tempTime[0] = Integer.parseInt(dateStr.substring(0, 2));// year
 tempTime[1] = Integer.parseInt(dateStr.substring(2, 4));// month
 tempTime[2] = Integer.parseInt(dateStr.substring(4, 6));// day
 tempTime[3] = Integer.parseInt(dateStr.substring(6, 8));// hh
 tempTime[4] = Integer.parseInt(dateStr.substring(8, 10));// mm
 tempTime[5] = Integer.parseInt(dateStr.substring(10, 12));// ss
 timeByte[0] = (byte) ((tempTime[0] << 2) + (tempTime[1] >> 2));
 timeByte[1] = (byte) (((tempTime[1] & 3) << 6) + (tempTime[2] << 1) + (tempTime[3] >> 4 & 1));
 timeByte[2] = (byte) (((tempTime[3] & 15) << 4) + ((tempTime[4] >> 2) & 15));
 timeByte[3] = (byte) (((tempTime[4] & 3) << 6) + tempTime[5]);
 return timeByte;
 }

 /**
  * 将byte数组转换成16进制字符串
  * 
  * @author linfenliang
  * @date 2012-6-19
  * @version V1.0.0
  * @param b:byte[]
  * @return String
  */
 public static String byteToHexStr(byte[] b) {
 StringBuffer sBuffer = new StringBuffer();
 for (byte bb : b) {
 sBuffer.append(Integer.toHexString(bb & 0xff));
 }
 return sBuffer.toString();
 }

 /**
  * 
  * @author linfenliang
  * @date 2012-6-19
  * @version V1.0.0
  * @param args
  *            void
  */
 public static void main(String[] args) {
 // TODO Auto-generated method stub
 byte[] b = strToByte("120509104354");
 System.out.println(byteToHexStr(b));
 }

}