fix:修复时间戳不连续的问题，接口新增docLength字段

src/main/java/com/njuzr/eaibackend/service/impl/BehaviorRecordServiceImpl.java

@@ -63,13 +63,11 @@ public class BehaviorRecordServiceImpl implements BehaviorRecordService {
 
     @Override
     public BehaviorRecordVO findALL(Long assignmentId, Long studentId) {
-        // 使用MongoDB聚合管道，直接在数据库层面展开events并投影所需字段
+        // 从behaviorOverviews集合中获取数据，因为其中的events时间戳已经是连续的
         Aggregation aggregation = Aggregation.newAggregation(
                 // 匹配条件 - 使用MongoDB字段名
                 Aggregation.match(Criteria.where("assignment_id").is(assignmentId)
                         .and("student_id").is(studentId)),
-                // 按创建时间降序排序 - 使用MongoDB字段名
-                Aggregation.sort(Sort.by(Sort.Direction.ASC, "created_at")),
                 // 展开events数组
                 Aggregation.unwind("events"),
                 // 投影所需字段
@@ -80,9 +78,10 @@ public class BehaviorRecordServiceImpl implements BehaviorRecordService {
                         .and("events.startStamp").as("startStamp")
                         .and("events.endStamp").as("endStamp")
                         .and("events.pauseTime").as("pauseTime")
+                        .and("events.docLength").as("docLength")
                         .and("created_at").as("createdAt"));
 
-        AggregationResults<Map> results = mongoTemplate.aggregate(aggregation, "behaviorRecords", Map.class);
+        AggregationResults<Map> results = mongoTemplate.aggregate(aggregation, "behaviorOverviews", Map.class);
         List<Map> mappedResults = results.getMappedResults();
 
         BehaviorRecordVO vo = new BehaviorRecordVO();
@@ -90,7 +89,7 @@ public class BehaviorRecordServiceImpl implements BehaviorRecordService {
         vo.setAssignmentId(assignmentId);
 
         if (!mappedResults.isEmpty()) {
-            // 获取第一条记录的创建时间
+            // 获取创建时间
             vo.setCreatedAt((Date) mappedResults.get(0).get("createdAt"));
 
             // 转换为SimplifiedEvent列表
@@ -116,6 +115,7 @@ public class BehaviorRecordServiceImpl implements BehaviorRecordService {
         simplified.setStartStamp((Long) map.get("startStamp"));
         simplified.setEndStamp((Long) map.get("endStamp"));
         simplified.setPauseTime((Long) map.get("pauseTime"));
+        simplified.setDocLength((Integer) map.get("docLength"));
 
         return simplified;
     }

src/main/java/com/njuzr/eaibackend/vo/BehaviorRecordVO.java

@@ -33,5 +33,6 @@ public class BehaviorRecordVO {
         // 结束时间信息
         private Long endStamp;       // 结束时间戳
         private Long pauseTime;      // 停留时间（毫秒）
+        private Integer docLength;      // 文档长度
     }
 }