原因： 数据库表中有一些字段不能为空，但在插入的过程中，有属性值为空。
com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Column ‘from_name’ cannot be null

com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Column 'from_name' cannot be null
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
	at com.mysql.jdbc.Util.getInstance(Util.java:384)
	at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1039)
	at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4232)
	...