Hibernate Mapping Types Example

Hello, in this tutorial we will see the different mapping types that are available in Hibernate.

1. Introduction

Hibernate is a framework that simplifies the development of Java application to interact with the database. It is an open source, lightweight, ORM (Object Relational Mapping) tool.

1.1 What is Hibernate?

  • Hibernate is the Opensource light weight ORM (Object Relational Mapping) based framework to communicate with the database. ORM is a programming technique that maps the object to the data stored in the database.
  • Hibernate framework makes the development of Java application interact with the database in a simple manner.
  • Hibernate handles mapping of Java classes to database tables (i.e. Java data types and SQL data types).
  • Hibernate also provides data query and retrieval facilities.
  • Hibernate is purely used for data persistence (i.e. to store/retrieve data from the database).
  • Hibernate framework internally uses the JDBC API to interact with the database. It hides internal JDBC implementations from end users.

1.2 Hibernate Advantages

  • Hibernate framework is Opensource and lightweight.
  • The performance of hibernate framework is fast because of caching mechanism which it uses internally.
  • Hibernate framework provides the facility to create the tables of the database automatically.
  • With the help of HQL (Hibernate Query Language), SQL queries generated are independent of databases.
  • Provides query facilities to fetch data from multiple databases.
  • Provides Transaction management and automatic key generations.
  • Provides various APIs for storing and retrieving Java objects directly to and from the database.
  • If there is a change in the database, then developers only need to change XML file properties.

1.3 Hibernate Supported Databases

Hibernate frameworks support various databases. Below are few names of databases that it supports:

  1. Oracle
  2. DB2
  3. Microsoft SQL Server
  4. MySQL
  5. PostgreSQL

and much more.

1.4 Download and Install Hibernate

You can read this tutorial in order to download and install Hibernate in the Eclipse IDE.

2. Hibernate Mapping Types Example

  • In the Hibernate mapping document, we have seen that Java data types are mapped to RDBMS data types
  • The types declared and used in the mapping files are not exactly Java data types. They are also not either SQL database types
  • These data types are called as Hibernate mapping types. This gets translated from Java to SQL data types and vice versa

Below is the complete list of the data type mapping:

Hibernate Type Database Type JDBC Type Type Registry
org.hibernate.type.StringType string VARCHAR string, java.lang.String
org.hibernate.type.MaterializedClob string CLOB materialized_clob
org.hibernate.type.TextType string LONGVARCHAR text
org.hibernate.type.CharacterType char, java.lang.Character CHAR char, java.lang.Character
org.hibernate.type.BooleanType boolean BIT boolean, java.lang.Boolean
org.hibernate.type.NumericBooleanType boolean INTEGER, 0 is false, 1 is true numeric_boolean
org.hibernate.type.YesNoType boolean CHAR, ‘N’/’n’ is false, ‘Y’/’y’ is true. The uppercase value is written to the database. yes_no
org.hibernate.type.TrueFalseType boolean CHAR, ‘F’/’f’ is false, ‘T’/’t’ is true. The uppercase value is written to the database. true_false
org.hibernate.type.ByteType byte, java.lang.Byte TINYINT byte, java.lang.Byte
org.hibernate.type.ShortType short, java.lang.Short SMALLINT short, java.lang.Short
org.hibernate.type.IntegerTypes int, java.lang.Integer INTEGER int, java.lang.Integer
org.hibernate.type.LongType long, java.lang.Long BIGINT long, java.lang.Long
org.hibernate.type.FloatType float, java.lang.Float FLOAT float, java.lang.Float
org.hibernate.type.DoubleType double, java.lang.Double DOUBLE double, java.lang.Double
org.hibernate.type.BigIntegerType java.math.BigInteger NUMERIC big_integer
org.hibernate.type.BigDecimalType java.math.BigDecimal NUMERIC big_decimal, java.math.bigDecimal
org.hibernate.type.TimestampType java.sql.Timestamp TIMESTAMP timestamp, java.sql.Timestamp
org.hibernate.type.TimeType java.sql.Time TIME time, java.sql.Time
org.hibernate.type.DateType java.sql.Date DATE date, java.sql.Date
org.hibernate.type.CalendarType java.util.Calendar TIMESTAMP calendar, java.util.Calendar
org.hibernate.type.CalendarDateType java.util.Calendar DATE calendar_date
org.hibernate.type.CurrencyType java.util.Currency VARCHAR currency, java.util.Currency
org.hibernate.type.LocaleType java.util.Locale VARCHAR locale, java.utility.locale
org.hibernate.type.TimeZoneType java.util.TimeZone VARCHAR (Using the TimeZone ID) timezone, java.util.TimeZone
org.hibernate.type.UrlType java.net.URL VARCHAR url, java.net.URL
org.hibernate.type.ClassType java.lang.Class VARCHAR (Using the class name) class, java.lang.Class
org.hibernate.type.BlobType java.sql.Blob BLOB blog, java.sql.Blob
org.hibernate.type.ClobType java.sql.Clob CLOB clob, java.sql.Clob
org.hibernate.type.BinaryType primitive byte[] VARBINARY binary, byte[]
org.hibernate.type.MaterializedBlobType primitive byte[] BLOB materized_blob
org.hibernate.type.ImageType primitive byte[] LONGVARBINARY image
org.hibernate.type.BinaryType java.lang.Byte[] VARBINARY wrapper-binary
org.hibernate.type.CharArrayType char[] VARCHAR characters, char[]
org.hibernate.type.CharacterArrayType java.lang.Character[] VARCHAR wrapper-characters, Character[], java.lang.Character[]
org.hibernate.type.UUIDBinaryType java.util.UUID BINARY uuid-binary, java.util.UUID
org.hibernate.type.UUIDCharType java.util.UUID CHAR, VARCHAR uuid-char
org.hibernate.type.PostgresUUIDType java.util.UUID PostgreSQL UUID pg-uuid
org.hibernate.type.SerializableType Implementors of java.lang.Serializable VARBINARY Unlike the other value types, multiple instances of this type are registered. It is registered once under java.io.Serializable and registered under the specific java.io.Serializable implementation class names

3. Conclusion

In this article, we discussed Hibernate types, which define the mapping of each Java type to an SQL type. It is the responsibility of the Hibernate dialect and the JDBC driver to convert the Java types to the actual target SQL types. This means a Java type may be transformed to different SQL types when different databases are used.

Although Hibernate provides a rich set of data types, called built-in types, some situations require the definition of a new type. Such situation occurs when you want to change Hibernate default behavior for mapping a Java type to an SQL type. Another situation is when you want to split up a class property to a set of table columns or merge a set of properties to a table column.

Built-in types include primitive, string, byte array, time, localization, serializable, and JDBC large types.

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