分治和hash-从海量数据大文件中查出某时间段内登陆超过阈值的ip地址 (三)
= new SimpleDateFormat(dateStyle);
return format.format(date);
}
/**
* 根据间隔时间，判断列表中的数据是否已经大于magic给出的魔法数
* 返回true or false
*
* @param dates
* @param intervalDate
* @param magic
* @return
* @throws ParseException
*/
public static boolean attack(List dateStrs,long intervalDate,int magic) {
if(dateStrs == null || dateStrs.size() < magic){
return false;
}
List dates = new ArrayList();
for(String date : dateStrs){
if(date != null && !"".equals(date))
dates.add(stringToDate(date,"yyyy-MM-dd hh:mm:ss"));
}
Collections.sort(dates);
return judgeAttack(dates,intervalDate,magic);
}
public static boolean judgeAttack(List sequenceDates,long intervalDate,int magic){
if(sequenceDates == null || sequenceDates.size() < magic){
return false;
}
for(int x = 0; x < sequenceDates.size() && x <= sequenceDates.size() - magic;x++){
Date dateAfter5 = new Date(sequenceDates.get(x).getTime() + intervalDate);
int count = 1;
for(int i = x + 1;i< sequenceDates.size();i++){
Date compareDate = sequenceDates.get(i);
if(compareDate.before(dateAfter5))
count ++ ;
else
break;
}
if(count >= magic)
return true;
}
return false;
}
/**
* 判断在间隔时间内，是否有大于magic的上限的数据集合，
* 如果有，则返回满足条件的集合
* 如果找不到满足条件的，就返回null
*
* @param sequenceDates 已经按照时间顺序排序了的数组
* @param intervalDate
* @param magic
* @return
*/
public static List attackTimes(List sequenceDates,long intervalDate,int magic){
if(sequenceDates == null || sequenceDates.size() < magic){
return null;
}
List res = new ArrayList();
for(int x = 0; x < sequenceDates.size() && x <= sequenceDates.size() - magic;x++){
Date souceDate = sequenceDates.get(x);
Date dateAfter5 = new Date(souceDate.getTime() + intervalDate);
res.add(souceDate);
for(int i = x + 1;i< sequenceDates.size();i++){
Date compareDate = sequenceDates.get(i);
if(compareDate.before(dateAfter5)){
res.add(compareDate);
}else
break;
}
if(res.size() >= magic)
return res;
else
res.clear();
}
return null;
}
public static List attackList(List dateStrs,long intervalDate,int magic){
if(dateStrs == null || dateStrs.size() < magic){
return null;
}
List dates = new ArrayList();
for(String date : dateStrs){
if(date != null && !"".equals(date))
dates.add(stringToDate(date,"yyyy-MM-dd hh:mm:ss"));
}
Collections.sort(dates);
return attackTimes(dates,intervalDate,magic);
}
}
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