com.mysql.jdbc.PacketTooBigException: Packet for query is too large (1078 > 1024

报错:

com.mysql.jdbc.PacketTooBigException: Packet for query is too large (1078 > 1024). You can change this value on the server by setting the max_allowed_packet' variable.
	at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3678) ~[mysql-connector-java-5.1.45.jar:5.1.45]
	at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2509) ~[mysql-connector-java-5.1.45.jar:5.1.45]
	at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2680) ~[mysql-connector-java-5.1.45.jar:5.1.45]
	at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2484) ~[mysql-connector-java-5.1.45.jar:5.1.45]
	at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1858) ~[mysql-connector-java-5.1.45.jar:5.1.45]
	at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:1197) ~[mysql-connector-java-5.1.45.jar:5.1.45]
	at com.alibaba.druid.filter.FilterChainImpl.preparedStatement_execute(FilterChainImpl.java:3051) [druid-1.1.8.jar:1.1.8]
	at com.alibaba.druid.filter.FilterAdapter.preparedStatement_execute(FilterAdapter.java:1080) ~[druid-1.1.8.jar:1.1.8]
	at com.alibaba.druid.filter.FilterChainImpl.preparedStatement_execute(FilterChainImpl.java:3049) [druid-1.1.8.jar:1.1.8]
	at com.alibaba.druid.filter.FilterEventAdapter.preparedStatement_execute(FilterEventAdapter.java:440) [druid-1.1.8.jar:1.1.8]
	at com.alibaba.druid.filter.FilterChainImpl.preparedStatement_execute(FilterChainImpl.java:3049) [druid-1.1.8.jar:1.1.8]
	at com.alibaba.druid.wall.WallFilter.preparedStatement_execute(WallFilter.java:619) [druid-1.1.8.jar:1.1.8]
	at com.alibaba.druid.filter.FilterChainImpl.preparedStatement_execute(FilterChainImpl.java:3049) [druid-1.1.8.jar:1.1.8]
	at com.alibaba.druid.filter.FilterEventAdapter.preparedStatement_execute(FilterEventAdapter.java:440) [druid-1.1.8.jar:1.1.8]
	at com.alibaba.druid.filter.FilterChainImpl.preparedStatement_execute(FilterChainImpl.java:3049) [druid-1.1.8.jar:1.1.8]
	at com.alibaba.druid.proxy.jdbc.PreparedStatementProxyImpl.execute(PreparedStatementProxyImpl.java:167) [druid-1.1.8.jar:1.1.8]
	at com.alibaba.druid.pool.DruidPooledPreparedStatement.execute(DruidPooledPreparedStatement.java:498) [druid-1.1.8.jar:1.1.8]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_191]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_191]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_191]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_191]
	at org.apache.ibatis.logging.jdbc.PreparedStatementLogger.invoke(PreparedStatementLogger.java:59) [mybatis-3.4.6.jar:3.4.6]
	at com.sun.proxy.$Proxy139.execute(Unknown Source) [na:na]

 原因：

MySQL根据配置文件会限制Server接受的数据包大小。有时候大的插入和更新会受 max_allowed_packet 参数限制，导致大数据写入或者更新失败。

解决：

进入数据库，执行：show VARIABLES like '%max_allowed_packet%';

太小导致出错。

在linux下，进入到mysql安装目录下，进入到：

/usr/local/mysql，找到my.cnf,增加一行

max_allowed_packet = 20M

如果没找到my.cnf，进入跟路径下：cd /  使用命令搜索：find -name my.cnf

重启mysql：service mysql restart

执行查看：show VARIABLES like '%max_allowed_packet%';

 执行代码，不报错误了。