我正试图通过JPA连接mysql,但它现在让我抓狂了。我不知道我是怎么做到的,但现在我重复一遍,我得到了这个例外:
[EL Warning]: metamodel: 2017-10-06 12:04:17.461--The collection of metamodel types is empty. Model classes may not have been found during entity search for Java SE and some Java EE container managed persistence units. Please verify that you
我创建了一个名为mypack的目录,并在该目录中添加了一个名为A.java的文件。A.java的代码如下: public A(){ }我在同一个目录中添加了另一个文件,名为Demo.java。该文件的代码如下: public static void main(String args[]) {
A a = new A(