前陣子在使用 mongo 查詢時碰到了一個很神奇的報錯信息，而且該報錯信息僅在服務器啓動後第一次查詢時會產生，後續繼續使用就又正常了。針對該問題排查許久未果。最近又重新斷點排查了一遍，終於發現了具體報錯的原因。
其實報錯原因很簡單，就是在使用註解定義索引時使用了中文的冒號（：），底層代碼無法解析該冒號，所以就報錯了。
我們項目的服務器啓動後的首次查詢時，會遍歷代碼中註解的索引，如果該索引在 mongo 中不存在，則爲 mongo 創建索引，已存在則不再處理。因此造成的現象就是每次服務器啓動後，第一次查詢時，總會報出題目中的錯誤。
如果有碰到類似問題的小夥伴，可以往這個方向排查看看。
大概的堆棧如下：
org.bson.json.JsonParseException: Invalid JSON input. Position: 16. Character: '：'.
at org.bson.json.JsonScanner.nextToken(JsonScanner.java:99)
at org.bson.json.JsonReader.popToken(JsonReader.java:492)
at org.bson.json.JsonReader.readBsonType(JsonReader.java:130)
at org.bson.codecs.DocumentCodec.decode(DocumentCodec.java:149)
at org.bson.codecs.DocumentCodec.decode(DocumentCodec.java:45)
at org.bson.Document.parse(Document.java:105)
at org.bson.Document.parse(Document.java:90)
at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.resolveCompoundIndexKeyFromStringDefinition(MongoPersistentEntityIndexResolver.java:376)
at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.createCompoundIndexDefinition(MongoPersistentEntityIndexResolver.java:345)
at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.lambda$createCompoundIndexDefinitions$2(MongoPersistentEntityIndexResolver.java:327)
at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
at java.util.Spliterators$ArraySpliterator.forEachRemaining(Spliterators.java:948)
at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499)
at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.createCompoundIndexDefinitions(MongoPersistentEntityIndexResolver.java:328)
at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.potentiallyCreateCompoundIndexDefinitions(MongoPersistentEntityIndexResolver.java:211)
at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.resolveIndexForEntity(MongoPersistentEntityIndexResolver.java:109)
at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexResolver.resolveIndexFor(MongoPersistentEntityIndexResolver.java:90)
at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexCreator.checkForAndCreateIndexes(MongoPersistentEntityIndexCreator.java:134)
at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexCreator.checkForIndexes(MongoPersistentEntityIndexCreator.java:127)
at org.springframework.data.mongodb.core.index.MongoPersistentEntityIndexCreator.onApplicationEvent(MongoPersistentEntityIndexCreator.java:111)
at com.exe.mongo.client.factory.MongoMappingEventPublisher.publish(MongoMappingEventPublisher.java:30)
at com.exe.mongo.client.factory.MongoMappingEventPublisher.publishEvent(MongoMappingEventPublisher.java:18)
at org.springframework.data.mapping.context.AbstractMappingContext.addPersistentEntity(AbstractMappingContext.java:420)
at org.springframework.data.mapping.context.AbstractMappingContext.getPersistentEntity(AbstractMappingContext.java:229)
at org.springframework.data.mapping.context.AbstractMappingContext.getPersistentEntity(AbstractMappingContext.java:172)
at org.springframework.data.mapping.context.AbstractMappingContext.getPersistentEntity(AbstractMappingContext.java:85)
at org.springframework.data.mapping.context.MappingContext.getRequiredPersistentEntity(MappingContext.java:70)