/**
 * Name: 比较两个字符串大小
 * Description: 比较的规则和数据库中的order by效果一致;
 *                 null自动转为空,空字符串最大;
 * 
 * @param first 要比较的第一个字符串;
 *           second 要比较的第二个字符串;
 * @return first大于second返回正数;
 *            first等于second返回0;
 *         first小于second返回负数;
 *         内部异常默认返回0;
 *         返回值非固定值哦~~;
 * @throws 
 * @Author 杨元
 */
public static int compareString(String first,String second){
  int result = 0;
  try{
    //null转空
    first = first==null?"":first;
    second = second==null?"":second;
    //预先记录字符串长度,避免反复读取
    int firstLength=first.length();
    int secondLength=second.length();
    //处理含有空串的特殊情况
    if("".equals(first) || "".equals(second)){
      //谁长谁小
      result = secondLength-firstLength;
    }else{
      //临时空间,用来存放ascii码总和
      int firstCount = 0;
      int secondCount = 0;
      //用纯运算得出两个数中较小的数,实在是bt
      int minLength = (secondLength*(firstLength/secondLength) + firstLength*(secondLength/firstLength))/(firstLength/secondLength + secondLength/firstLength);
      //按两个字符串中较短的位数去逐位截取,防止越界
      for(int i=0;i<minLength;i++){
        //求ascii码和
        firstCount+=first.substring(i,i+1).getBytes()[0];
        secondCount+=second.substring(i,i+1).getBytes()[0];
        //和不相等,说明已经比较出了大小
        if(firstCount!=secondCount){
          break;
        }
      }
      if(firstCount==secondCount){
        //长度长的大
        result = firstLength-secondLength;
      }else{
        //总和大的大
        result = firstCount-secondCount;
      }
    }
  }catch (Exception e) {}
  return result;
}
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