Mapping And Configuration Files In Hibernate
Mapping and Configuration are very familiar keywords we used to here in the hibernate, every hibernate program must need these 2 xml files.Mapping:
- Mapping file is the heart of hibernate application.
- Every ORM tool needs this mapping, mapping is the mechanism of placing an object properties into column’s of a table.
- Mapping can be given to an ORM tool either in the form of an XML or in the form of the annotations.
- The mapping file contains mapping from a pojo class name to a table name and pojo class variable names to table column names.
- While writing an hibernate application, we can construct one or more mapping files, mean a hibernate application can contain any number of mapping files.
- Identity (Object Name)
- State (Object values)
- Behavior (Object Methods)
- XML
- Annotations.
Syntax Of Mapping xml:
<hibernate-mapping>
<class name="POJO class name" table="table name in database"> <id name="variable name" column="column name in database" type="java/hibernate type" /> <property name="variable1 name" column="column name in database" type="java/hibernate type" /> <property name="variable2 name" column="column name in database" type="java/hibernate type" /> </class> </hibernate-mapping>
Configuration:
Configuration is the file loaded into an hibernate application when working with hibernate, this configuration file contains 3 types of information..- Connection Properties
- Hibernate Properties
- Mapping file name(s)
No. of databases we are using = That many number of configuration filesWe can write this configuration in 2 ways…
- xml
- By writing Properties file. We don’t have annotations here, actually in hibernate 1, 2.x we defined this configuration file by writing .properties file, but from 3.x xml came into picture.
Mapping –> xml, annotations
Configuration –> xml, .properties (old style)
Syntax Of Configuration xml:
<hibernate-configuration> <session-factory> <!-- Related to the connection START --> <property name="connection.driver_class">Driver Class Name </property> <property name="connection.url">URL </property> <property name="connection.user">user </property> <property name="connection.password">password</property> <!-- Related to the connection END --> <!-- Related to hibernate properties START --> <property name="show_sql">true/false</property> <property name="dialet">Database dialet class</property> <property name="hbm2ddl.auto">create/update or what ever</property> <!-- Related to hibernate properties END--> <!-- Related to mapping START--> <mapping resource="hbm file 1 name .xml" / > <mapping resource="hbm file 2 name .xml" / > <!-- Related to the mapping END --> </session-factory> </hibernate-configuration>
But XML files are always recommended to work.
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