import java.sql.Date;
int year = 1990;
int month = 12;
int day = 12;
System.out.println(Date.valueOf(year + "-" + month + "-" + day));
运行报错, 严重: Servlet.service() for servlet [EmployeeServlet] in context with path [/Employee] threw exception java.lang.IllegalArgumentException at java.sql.Date.valueOf(Date.java:138)