diff --git a/Chapter4-2-5/src/main/java/com/didispace/log/MongoAppender.java b/Chapter4-2-5/src/main/java/com/didispace/log/MongoAppender.java
index 5380d12..e81f511 100644
--- a/Chapter4-2-5/src/main/java/com/didispace/log/MongoAppender.java
+++ b/Chapter4-2-5/src/main/java/com/didispace/log/MongoAppender.java
@@ -1,18 +1,12 @@
 package com.didispace.log;
 
 import com.mongodb.BasicDBObject;
-import com.mongodb.DBObject;
 import com.mongodb.MongoClient;
 import com.mongodb.MongoClientURI;
 import com.mongodb.client.MongoCollection;
 import com.mongodb.client.MongoDatabase;
 import org.apache.log4j.AppenderSkeleton;
 import org.apache.log4j.spi.LoggingEvent;
-import org.bson.Document;
-
-import java.io.ByteArrayOutputStream;
-import java.io.IOException;
-import java.io.ObjectOutputStream;
 
 /**
  * 日志插入MongoDB