修复计算热搜排名由于历史数据错误导致的当前数据错误问题，并添加上一次的排名及热度功能

src/main/java/com/zhiwei/searchhotcrawler/dao/HotSearchCacheDAO.java

@@ -68,7 +68,6 @@ public class HotSearchCacheDAO  {
            boolean hot = document.getBoolean("hot")!=null?document.getBoolean("hot"):true;
            String url = document.getString("url")!=null?document.getString("url"):null;
            String id = name + "_" + type;
-
            Document query = new Document("_id", id);
            Document nowDoc = (Document) collection.find(query).first();
            if (Objects.nonNull(nowDoc)) {
@@ -79,6 +78,9 @@ public class HotSearchCacheDAO  {
                    highestCount = lastCount;
                }
                //判断最高排名
+               if (highestRank<0){
+                   highestRank = lastRank;
+               }
                if (lastRank>0 && highestRank>0 && lastRank < highestRank) {
                    highestRank = lastRank;
                }
@@ -92,6 +94,8 @@ public class HotSearchCacheDAO  {
                nowDoc.put("lastCount", lastCount);
                nowDoc.put("highestRank", highestRank);
                nowDoc.put("highestCount", highestCount);
+               nowDoc.put("preRank", null);
+               nowDoc.put("preCount", null);
                nowDoc.put("duration", durationNow);
                collection.replaceOne(query, nowDoc);
            } else {
@@ -110,6 +114,8 @@ public class HotSearchCacheDAO  {
                nowDoc.put("startTime", startTime);
                nowDoc.put("endTime", endTime);
                nowDoc.put("duration", durationNow);
+               nowDoc.put("preRank", nowDoc.getInteger("lastRank"));
+               nowDoc.put("preCount", nowDoc.getInteger("lastCount"));
 
                collection.insertOne(nowDoc);
            }