java split 中的坑

System.out.println(":ab:cd:ef::".split(":").length);//末尾分隔符全部忽略    

System.out.println(":ab:cd:ef::".split(":",-1).length);//不忽略任何一个分隔符    

System.out.println(StringUtils.split(":ab:cd:ef::",":").length);//最前面的和末尾的分隔符全部都忽略,apache commons    
  System.out.println(StringUtils.splitPreserveAllTokens(":ab:cd:ef::",":").length);//不忽略任何一个分隔符 apache commons