I am involved in writing a project which requires servlet->database connection. I am collaborating with another person who have designed a database using HyperSQL (hsqldb), I am now trying to merge my project with his by adding his code to mine.
Further to my issue though. When I copy the code, it works, usually. I have few methods that use the data from the database and compare them with user input.
When attempting to connect to the database, I would randomly succeed or fail, getting the following error ;
Unable to acquire a connection from driver [null]
I of course initialise a driver ;
Class.forName("org.hsqldb.jdbcDriver").newInstance();
Now, when running my method, it sometimes succeeds, and sometimes fails, here is the XML file for the DB;
<?xml version="1.0" encoding="UTF-8"?>
<!--
Creates both the HyperSQL databases using hibernate. No password or username is set.
-->
<persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
<persistence-unit name="monsters" transaction-type="RESOURCE_LOCAL">
<class>databaseManagement.Monster</class>
<exclude-unlisted-classes>true</exclude-unlisted-classes>
<properties>
<property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
<property name="hibernate.connection.username" value=""/>
<property name="hibernate.connection.password" value=""/>
<property name="hibernate.connection.url" value="jdbc:hsqldb:monsters"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
<property name="hibernate.hbm2ddl.auto" value="update"/>
</properties>
</persistence-unit>
<persistence-unit name="users" transaction-type="RESOURCE_LOCAL">
<class>databaseManagement.User</class>
<exclude-unlisted-classes>true</exclude-unlisted-classes>
<properties>
<property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
<property name="hibernate.connection.username" value=""/>
<property name="hibernate.connection.password" value=""/>
<property name="hibernate.connection.url" value="jdbc:hsqldb:users"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
<property name="hibernate.hbm2ddl.auto" value="update"/>
</properties>
</persistence-unit>
</persistence>
Probably an attempt is made to open the database in a readonly directory.
You need to specify a username for both persistence units. The default username is "SA".
The file path of the database that you specify in the URL is relative. It resolves to the execution directory. As you are developing a web application, you need to specify a directory that can be written to.
One way of doing this is by including a variable in the path, such as "jdbc:hsqldb:file:{$directorypath}/monsters" where the directorypath is the name of the web application's data dirctory, as specified in your web.xml file.
Related
In a maven-java-sql project using hibernate, when I try to run the project this error message appears. The MySQL server is running but the the maven-java project is not able to comunicate with the MySQL server. I am using the Apache NetBeans IDE and Workbench as the server tool. Here is my persistence class
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
<persistence-unit name="Persistence" transaction-type="RESOURCE_LOCAL">
<!-- Persistence provider -->
<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
<properties>
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/technikon"/>
<property name="javax.persistence.jdbc.user" value="root"/>
<property name="javax.persistence.jdbc.password" value="root"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
<property name="hibernate.show_sql" value="true"/>
<property name="hibernate.hbm2ddl.auto" value="create"/>
</properties>
</persistence-unit>
</persistence>
the error message
The error message tells you that:
Caused by: java.sql.SQLSyntaxErrorException: Unknown database 'technikon'
So, you will need to connect to your RDBMS via Workbench (or CLI or whatever) and run
show databases;
See what databases you are finding in the list (beware db names like Technikon) and change your settings accordingly.
I need to fill my database on ear startup, so I add javax.persistence.sql-load-script-source tag with reference to the file.
<persistence-unit name="MyPU" transaction-type="JTA">
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
<jta-data-source>java:/jboss/datasource/mydatasource</jta-data-source>
<jar-file>Entities.jar</jar-file>
<exclude-unlisted-classes>false</exclude-unlisted-classes>
<properties>
<property name="javax.persistence.schema-generation.database.action" value="create"/>
<property name="eclipselink.logging.logger" value="org.eclipse.persistence.logging.DefaultSessionLog"/>
<property name="eclipselink.logging.level" value="ALL"/>
<property name="eclipselink.logging.level.sql" value="ALL"/>
<property name="javax.persistence.sql-load-script-source" value="META-INF/defaultdata.sql"/>
<property name="javax.persistence.sql-load-script-source" value="META-INF/insertnations.sql"/>
</properties>
</persistence-unit>
It works, but now i want to use two file because i want to separate "most static" data (like nations and regions of the world) from "per-deploy" data (like some configurations).
Using the tag twice not works.
Is there something wrong?
It is possible to do what i want?
The persistence unit is used in a EAR. I use Wildfly and eclipselink 2.5.2 as persistence provider
I have a web application that I use JPA / Hibernate I want to know how to hibernate can generate the non-existent tables from entities.
the persistence file is as follows:
What I can add as property ?
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
version="1.0">
<persistence-unit name="BankingApp">
<provider> org.hibernate.ejb.HibernatePersistence</provider>
<properties>
<property name="hibernate.connection.driver_class" value="oracle.jdbc.driver.OracleDriver"/>
<property name="hibernate.connection.url" value="jdbc:oracle:thin:#localhost:1521:XE"/>
<property name="hibernate.connection.username" value="user"/>
<property name="hibernate.connection.password" value="password"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect"/>
</properties>
</persistence-unit>
</persistence>
You can add this property
<property name="hibernate.hbm2ddl.auto" value="update"/>
The possible values for this property are:
validate: Only validates the schema
update: Update the schema
create: Create the schema, override previous data
create-drop: Create the schema and drop the schema at the end of the session
I found the solution, simply add the following property:
<property name="hibernate.hbm2ddl.auto" value="create"/>
I have a standalone java application, which uses JPA for its persistence.
Right now I have a persistence.xml in META-INF.My application is currently in development.
My question is that if I move from development to the next envirnoment, say QA. I have to modify the persistence.xml and rebuild the jar. Is this the right way to go about it ?
If not,if I move the connection properties to a different file, where should this file be placed?
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd" version="2.0">
<persistence-unit name="pu1" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<class>ClassA</class>
<class>ClassB</class>
<class>ClassC</class>
<class>ClassD</class>
<properties>
<property name="hibernate.dialect" value="org.hibernate.dialect.Oracle9Dialect" />
<property name="hibernate.connection.driver_class" value="oracle.jdbc.OracleDriver" />
<property name="hibernate.show_sql" value="true" />
<property name="hibernate.connection.username" value="username" />
<property name="hibernate.connection.password" value="password" />
<property name="hibernate.connection.url"
value="url" />
<property name="hibernate.max_fetch_depth" value="3" />
<property name="hibernate.archive.autodetection" value="class" />
</properties>
</persistence-unit>
</persistence>
Thanks in advance !
That's a good question. Normally, you put all these environment settings in an external file, say application.properties, and pass the location to it to the JVM when you start your application (e.g. -Dconfig.location=/conf/)
Then you should find a way to get the externalized properties into your EntityManagerFactory. You can't do that in persistence.xml, you can only hard-code things there. But you can do it when creating the entity manager factory by passing vendor properties.
If using a framework like spring, for example, this is easier to do, as spring provides a factory bean for the entity manager. Otherwise you should handle it yourself. Here's the relevant bit from spring:
provider.createEntityManagerFactory(persistenceUnitInfo, getJpaPropertyMap())
I am trying to change my web-app's JDBC code to JPA using Hibernate as provider. I am using Eclipse IDE. In that i have defined a MySQL data source. I added it in the persistence.xml.
But, I am getting the below error.
6640 [30289364#qtp-7494106-7] ERROR org.hibernate.connection.DatasourceConnectionProvider - Could not find datasource: tamSql
javax.naming.NameNotFoundException; remaining name 'tamSql'
My persistence.xml looks like,
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
<persistence-unit name="ExpensePersistentUnit" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<non-jta-data-source>tamSql</non-jta-data-source>
<class>com.pricar.JPAInteg.Role</class>
<class>com.pricar.JPAInteg.User</class>
<class>com.pricar.JPAInteg.Userdetail</class>
<class>com.pricar.JPAInteg.Category</class>
<class>com.pricar.JPAInteg.Expens</class>
<class>com.pricar.JPAInteg.Leavetable</class>
<class>com.pricar.JPAInteg.Permissiontoken</class>
<class>com.pricar.JPAInteg.Roletokenassociation</class>
<class>com.pricar.JPAInteg.UserPK</class>
<properties>
<property name="hibernate.connection.url" value="jdbc:mysql://localhost/officemgmt"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"></property>
<property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/>
<property name="hibernate.connection.password" value="1234"/>
<property name="hibernate.connection.username" value="root"/>
<property name="hibernate.hbm2ddl.auto" value="update"/>
<property name="hibernate.show_sql" value="true"/>
</properties>
Any Suggestions!!!
Thanks in Advance!
You don't need <non-jta-data-source> when your datasource is configured in <properties>. <non-jta-data-source> is needed when datasource is configured in application server configuration and obtained via JNDI.