mysql修改默认字段大小

往mysql里面存MP3文件时，总是报

Exception in thread "main" com.mysql.jdbc.PacketTooBigException: Packet for query is too large (5406613 > 1048576). You can change this value on the server by setting the max_allowed_packet' variable.
at com.mysql.jdbc.MysqlIO.send(MysqlIO.java:3248)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1940)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2113)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2568)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2113)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2409)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2327)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2312)
at mp3存取mysql.demo.main(demo.java:38)

经过排查错误，是默认mysql默认字段大小1048576小于我要上传的MP3文件，所以报异常。

因为在windows下，所以去找mysql安装目录下的配置文件my.ini，进入后，要是有max_allowed_packet = 1M，则更改默认数值大小，要是没有，则手动添加末尾（数值大小，自己设定），重新运行程序即可。