每当我向ID字段添加“ @GeneratedValue”注释时,我都面临上述问题。 请参阅下面的代码片段,我已使用它们使用休眠功能保存实体。
public class HibernateTest {
public static void main(String[] args) {
Employee emp1 = new Employee();
emp1.setName("User1");
try (SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory(); Session session = sessionFactory.openSession()){
session.beginTransaction();
session.save(emp1);
session.getTransaction().commit();
} catch (Exception e) {
e.printStackTrace();
}
}
}
下面是我的Entity类
@Entity
@Table (name = "Employee_Details")
public class Employee {
@Id @GeneratedValue(strategy=GenerationType.AUTO)
private int id;
private String name;
public int getId() { return id; }
public void setId(int id) { this.id = id; }
public String getName() {
return name;
}
public void setName(String name) { this.name = name; }
}
在hibernate.cfg.xml中,连接池大小设置为1
<property name="connection.pool_size">1</property>
我每次都关闭会话以及sessionFactory实例。仍然面临日志中的异常
org.hibernate.HibernateException: The internal connection pool has reached its maximum size and no connection is currently available!
at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl$PooledConnections.poll(DriverManagerConnectionProviderImpl.java:322)
at org.hibernate.engine.jdbc.connections.internal.DriverManagerConnectionProviderImpl.getConnection(DriverManagerConnectionProviderImpl.java:189)
at org.hibernate.internal.NonContextualJdbcConnectionAccess.obtainConnection(NonContextualJdbcConnectionAccess.java:35)
at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcIsolationDelegate.delegateWork(JdbcIsolationDelegate.java:48)
at org.hibernate.id.enhanced.TableStructure$1.getNextValue(TableStructure.java:125)
at org.hibernate.id.enhanced.NoopOptimizer.generate(NoopOptimizer.java:40)
如果我从ID字段中删除了'GeneratedValue'注释,则可以正常工作。谁能告诉我,为什么会失败?以及如何解决?
答案 0 :(得分:1)
我遇到了这个问题,并通过替换来解决了该问题:
@GeneratedValue(strategy = GenerationType.AUTO)
具有:
@GeneratedValue(strategy = GenerationType.IDENTITY)
希望它也对您有用!
答案 1 :(得分:0)
我认为它使用连接来确定“ id”。 也许将连接数设置为2而不是1可以解决问题。