我是Java / Hibernate的新手，也不知道此错误是什么意思。
ERROR: Connection leak detected: there are 1 unclosed connections upon shutting down pool jdbc:mysql://localhost:3306/hb_student_records?useSSL=false&serverTimezone=UTC
Exception in thread "main" org.hibernate.HibernateException: The internal connection pool has reached its maximum size and no connection is currently available!
我在Stack Overflow的其他论坛上查找了答案，但在那里没有任何意义。
我的课程如下：
创建学生演示
package com.rsharma.hibernate.demo;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import com.rsharma.hibernate.demo.entity.Student;
public class CreateStudentDemo {
public static void main(String[] args) {
// create session factory
SessionFactory factory = new Configuration()
.configure("hibernate.cfg.xml")
.addAnnotatedClass(Student.class)
.buildSessionFactory();
// create session
Session session = factory.getCurrentSession();
try {
// create a student object
System.out.println("Creating new student object...");
Student tempStudent = new Student("Rishav", "Sharma", "paul@luv2code.com");
// start a transaction
session.beginTransaction();
// save the student object
System.out.println("Saving the student...");
session.save(tempStudent);
// commit transaction
session.getTransaction().commit();
System.out.println("Done!");
}
finally {
factory.close();
}
}
}
Student.java
package com.rsharma.hibernate.demo.entity;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
@Entity
@Table(name="student")
public class Student {
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
@Column(name="id")
private int id;
@Column(name="first_name")
private String firstName;
@Column(name="last_name")
private String lastName;
@Column(name="email")
private String email;
public Student(){
}
public Student(String firstName, String lastName, String email) {
this.firstName = firstName;
this.lastName = lastName;
this.email = email;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
@Override
public String toString() {
return "Student [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + ", email=" + email + "]";
}
}
还有我的config.xml文件
hibernate.cfg.xml
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- JDBC Database connection settings -->
<property name="connection.driver_class">com.mysql.cj.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost:3306/hb_student_records?useSSL=false&serverTimezone=UTC</property>
<property name="connection.username">hbstudent</property>
<property name="connection.password">hbstudent</property>
<!-- JDBC connection pool settings ... using built-in test pool -->
<property name="connection.pool_size">1</property>
<!-- Select our SQL dialect -->
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<!-- Echo the SQL to stdout -->
<property name="show_sql">true</property>
<!-- Set the current session context -->
<property name="current_session_context_class">thread</property>
</session-factory>
</hibernate-configuration>
我不知道是什么原因导致我打开连接，因为我已经关闭班级的工厂并且会话是临时的。
答案 0 :(得分：2)
我认为您还应该在关闭工厂对象之前冲洗并关闭会话对象。
答案 1 :(得分：1)
它对我不起作用：（
public static void main(String[] args) {
//craete sessionfactory
SessionFactory factory = new Configuration().configure("hibernate.cfg.xml").addAnnotatedClass(Student.class).buildSessionFactory();
//craete session
Session session = factory.getCurrentSession();
try {
//use the seesion to save the object
System.out.println("Creating the student object ...");
Student student = new Student("abc","fgh","jklop@gmail.com");
//start the tranction
session.beginTransaction();
//save the student object
System.out.println("Saving the Student...");
session.save(student);
//commit the tranction
session.getTransaction().commit();
System.out.println("Commit Done!!");
}catch(Exception exe) {
session.flush();
session.close();
factory.close();
}
}
答案 2 :(得分：0)
在下面的实体类中使用 @GeneratedValue（strategy = GenerationType.IDENTITY）
答案 3 :(得分：0)
此问题的快速解决方法是用旧的Hibernate 5.2 jar文件替换最新的Hibernate软件包。
实际上问题不在于连接池，try and catch块中存在某些对象类型不匹配，您可以删除try and catch块并查看真正的异常是什么。
也许休眠专家可以回答这个问题。
当然，“在关闭工厂对象之前刷新并关闭会话对象”对您没有帮助。
答案 4 :(得分：0)
答案 5 :(得分：0)
您好，我怀疑您看到删除@GenerationType(Strategy=GeneratedValue.Identity)行，
因为我猜您在主键列中使用了自动递增。
@GenerationType(Strategy=GeneratedValue.Identity)仅在您想在数据库中保存多个对象时使用。
答案 6 :(得分：0)
您应该更改
MainScreen到
class MainScreen(Screen):
def update(self):
Scanner.change_number()
然后它将起作用。
答案 7 :(得分：0)
为我解决的是为每个事务创建一个新的 EntityManager 并在每个事务之后像这样关闭它。
} finally {
session.close();
entityManager.close();
}