补零后，输出出现三位数
public static void printHexByByteArray(String fileName) throws IOException {
FileInputStream in=new FileInputStream(fileName);
byte[] buf=new byte[1*1024];
int b=in.read(buf, 0, buf.length);
int j=1;
for (int i = 0; i < b; i++) {
if (buf[i]<=0xf) {
System.out.print("0");
}
System.out.print(Integer.toHexString(buf[i] & 0xff)+" ");
if(j++%10==0){
System.out.println();
}
}
in.close();
}
