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This article mainly introduces how to apply the Hibernate configuration file in the unit test, which has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, let the editor take you to understand it.

Hibernate is a popular open source object-relational mapping tool, and the importance of unit testing and continuous integration has been widely promoted and recognized. How to ensure the automation and persistence of testing in projects that adopt Hibernate? This article discussed the process of Hibernate configuration files hibernate.properties and hibernate.cfg.xml, and how to flexibly apply the access methods of configuration files provided by hibernate to unit testing.

Introduction

Hibernate is a popular open source object-relational mapping tool, and the importance of unit testing and continuous integration has been widely promoted and recognized. How to ensure the automation and persistence of testing in projects that adopt Hibernate? This article discussed the process of Hibernate loading its configuration files hibernate.properties and hibernate.cfg.xml, and how to flexibly apply the access methods of configuration files provided by hibernate to unit testing. Note: this article uses hibernate2.1 as the basis for discussion, and there is no guarantee that the views of this article are appropriate for other versions.

1. Prepare for

For beginners of hibernate, the experience of using hibernate for * * times is usually:

1) after installing and configuring Hibernate, we will use% HIBERNATE_HOME% as a reference to the Hibernate installation directory

2) start creating your own * * examples, such as the class Cat in the hibernate manual

3) configure the hbm mapping file (e.g. Cat.hbm.xml, the meaning of the configuration items in this file is not discussed in this article) and the database (e.g. hsqldb)

4) add a hibernate.cfg.xml file under the classpath path of the project, as follows (* use the most common configuration content of hibernate for * * times):

< hibernate-configuration > < session-factory > < property name=" connection.url "> jdbc:hsqldb:hsql://localhost < / property > < property name=" connection.driver_class "> org.hsqldb.jdbcDriver < / property > < property name= "connection.username" > sa < / property > < property name= "connection.password" > < / property > < property name= "dialect" > net.sf.hibernate.dialect.HSQLDialect < / property > < property name= "hibernate.show_sql" > false < / property > < mapping resource= "Cat.hbm.xml" / > < / session-factory > < / hibernate-configuration >

5) then you need to provide a class to test create, update, delete and query Cat. For developers who are familiar with JUnit, you can create a unit test class to test, as follows:

Import junit.framework.TestCase; import net.sf.hibernate.HibernateException; import net.sf.hibernate.Session; import net.sf.hibernate.Transaction; import net.sf.hibernate.cfg.Configuration; public class CatTest extends TestCase {private Session session; private Transaction tx; protected void setUp () throws Exception {Configuration cfg = new Configuration (). Configure (); / pay attention to this line, which is the focus of this article. Session = cfg.buildSessionFactory (). OpenSession (); tx = session.beginTransaction ();} protected void tearDown () throws Exception {tx.commit (); session.close ();} public void testCreate () {/ / Please add relevant code to this method. This article does not discuss how to use Hibernate API. } public void testUpdate () {/ / Please add the relevant code to this method. This article does not discuss how to use Hibernate API. } public void testDelete () {/ / Please add the relevant code to this method. This article does not discuss how to use Hibernate API. } public void testQuery () {/ / Please add the relevant code to this method. This article does not discuss how to use Hibernate API. }}

2. What has new Configuration () done?

For novices who use hibernate for many times, the following code is arguably the most common way to use Configuration.

Configuration cfg = new Configuration () .configure ()

Configuration is the entrance to hibernate. When creating a new instance of Configuration, hibernate will look for the hibernate.properties file in classpath. If the file exists, the contents of the file will be loaded into an instance GLOBAL_PROPERTIES of Properties. If it does not exist, the information will be printed.

Hibernate.properties not found

Then all system environment variables (System.getProperties ()) are also added to the GLOBAL_PROPERTIES (Note 1). If the hibernate.properties file exists, the system will also verify the validity of the file configuration, and the system will print a warning message for some configuration parameters that are no longer supported.

3. What is configure () doing?

At this point in the discussion of new Configuration (), let's discuss the configure () method.

The configure () method looks for the hibernate.cfg.xml file under classpath by default, and if the file is not found, the system prints the following information and throws a HibernateException exception.

Hibernate.cfg.xml not found

If the file is found, the configure () method will first access < session-factory > and get the name attribute of the element. If it is not empty, it will overwrite the configuration value of hibernate.properties 's hibernate.session_factory_name with the value of this configuration. From this, we can see that the configuration information in hibernate.cfg.xml can override the configuration information of hibernate.properties.

Then the configure () method accesses the child elements of < session-factory >, first using all the configuration information of the < property > element (Note 2), such as the configuration file we used earlier

< property name= "connection.url" > jdbc:hsqldb:hsql://localhost < / property > < property name= "connection.driver_class" > org.hsqldb.jdbcDriver < / property > < property name= "connection.username" > sa < / property > < property name= "connection.password" > < / property > < property name= "dialect" > net.sf.hibernate.dialect.HSQLDialect < / property >

The corresponding configuration in hibernate.properties will be overwritten. The values in the hibernate.properties file (under% HIBERNATE_HOME%/etc) included in the hibernate2.1 release package are as follows:

Hibernate.dialect net.sf.hibernate.dialect.HSQLDialect hibernate.connection.driver_class org.hsqldb.jdbcDriver hibernate.connection.username sa hibernate.connection.password hibernate.connection.url jdbc:hsqldb:hsql://localhost

Then configure () accesses the contents of the following elements sequentially

< mapping > < jcs-class-cache > < jcs-collection-cache > < collection-cache >

Where < mapping > is essential, configure () can only access the mapping file (hbm.xml) of the Java object and relational database table we defined by configuring < mapping >, for example:

< mapping resource= "Cat.hbm.xml" / >

From the above analysis, we have a clear understanding of the default loading process of the Hibernate configuration files hibernate.properties and hibernate.cfg.xml.

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