Hibernate-MySQL connection

Question

I am one newbie at Java web. I am developing an application with Java web by using Hibernate and MySQL. The problem is when I try to log in sometimes it throws Communication link failure exception if I try to connect remote database. What may cause this problem? (I also changed time out value again it throws exception.)

Hibernate version : 4.3.3.Final

Glassfish Server : 4.1

Related error ss : http://hackengine-er.com/exceptions/link-failure.png

Project Source Codes : https://github.com/Muslum10cel/Vaccine

my hibernate.cfg.xml :

    <?xml version="1.0" encoding="UTF-8"?>
    <hibernate-configuration>
      <session-factory>
        <property name="hibernate.dialect">{MySQLDialect}</property>
        <property name="hibernate.connection.driver_class">{jdbcdriver}</property>
        <property name="hibernate.connection.url">{connectionstring}</property>
        <property name="hibernate.connection.username">{username}</property>
        <property name="hibernate.connection.password">{password}</property>
        <property name="hibernate.show_sql">true</property>
        <property name="hibernate.hbm2ddl.auto">update</property>
        <property name="hibernate.current_session_context_class">thread</property>
        <property name="hibernate.c3p0.timeout">0</property>
     </session-factory>

      <!-- Entity mappings -->
   </hibernate-configuration>

Thanks for your help

Answer 1

As a first step, i would suggest changing a few configurations:

1. Use org.hibernate.dialect.MySQL5Dialect instead of org.hibernate.dialect.MySQLDialect
2. Use this Driver com.mysql.cj.jdbc.Driver instead of com.mysql.jdbc.Driver
3. remove the ?autoReconnect=true
4. You're accessing the DB using root user, I would suggest creating a dedicated user
5. You didn't mention any password. even if you're using root user, it has a password. use it.

org.hibernate.dialect.MySQL5Dialect

<property name="hibernate.connection.driver_class">com.mysql.cj.jdbc.Driver</property> 

<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/vaccine</property>

<property name="hibernate.connection.username">root</property>

<property name="hibernate.connection.password">root_password_missing</property>