java - How to read database configuration parameter using properties file in hibernate

Question

In my apps I am using hibernate, to connect a with database and create a session. this is my hibernate.cfg.xml file. This is ok. It working properly.

<?xml version="1.0" encoding="UTF-8"?>
 <!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>
        <!-- Database connection settings -->
        <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="connection.url">jdbc:mysql://localhost:3306/country</property>
        <property name="connection.username">root</property>
        <property name="connection.password">password</property>

    </session-factory>

</hibernate-configuration>

But when I try to read the DB configuration properties using db.property file using this hibernate.cfg.xml, it showing Exception, this is my another hibernate.cfg.xml file

<util:properties id="db" location="classpath:db.properties" />

<hibernate-configuration>

    <session-factory>
        <!-- Database connection settings -->
        <property name="driverClassName" value="#{db['driverClassName']}"></property>
        <property name="url" value="#{db['url']}"></property>
        <property name="username" value="#{db['username']}"></property>
        <property name="password" value="#{db['password']}"></property>

    </session-factory>

</hibernate-configuration>

this is the error

 org.dom4j.DocumentException: Error on line 8 of document  : The prefix "util" for       element "util:properties" is not bound. Nested exception: The prefix "util" for element   "util:properties" is not bound.
    at org.dom4j.io.SAXReader.read(SAXReader.java:482)
    at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:2155)

this is my properties file named db.properties

driverClassName=com.mysql.jdbc.Driver

url=jdbc:mysql://localhost:3306/country

username=root

password=password

what is the problem is there? how to do that properly

Answer 1

util:properties is not a valid tag to use in hibernate.cfg.xml file. If you want to place all the DB configuration details in a properties file then you can place them in hibernate.properties file and remove those from hibernate.cfg.xml file. In this way the DB details will be maintained in properties file.

If you want to maintain a separate file instead of using hibernate.properties file then you can try this:

java.util.Properties properties = new Properties();
properties.load(new FileInputStream("db.properties"));

Configuration configuration = new Configuration();

configuration.configure("hibernate.cfg.xml").addProperties(properties);;

ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
.applySettings(configuration.getProperties()).build();

SessionFactory sessionFactory = configuration
.buildSessionFactory(serviceRegistry);