正如异常所说:Calendar::getTime() 返回一个 java.util.Date 对象，而不是 java.sql.Timestamp 对象.所以你不能将它转换为 Timestamp 对象.

As the exception says: Calendar::getTime() returns a java.util.Date object, not a java.sql.Timestamp object. So you cannot cast it to a Timestamp object.

用途:

Timestamp timestamp = new Timestamp(cal.getTimeInMillis());

并且还考虑替换 Calendar 带有新的 日期 &Java SE 8 中引入的时间 API.