Revision as of 11:56, 27 October 2011

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Key API

• @Lob

@Lob

By default, the EclipseLink persistence provider assumes that all persistent data can be represented as typical database data types.

Use the @Lob annotation with the @Basic mapping to specify that a persistent property or field should be persisted as a large object to a database-supported large object type.

A Lob may be either a binary or character type. The persistence provider infers the Lob type from the type of the persistent field or property.

For String and character-based types, the default is Clob. In all other cases, the default is Blob.

You can also use the @Column attribute columnDefinition to further refine the Lob type.

For more information, see Section 11.1.9 "Column Annotation" in the JPA Specification.

The @Lob annotation does not have attributes.

The following example shows how to use this @Lob annotation to specify that persistent field pic should be persisted as a Blob.

Example: @Lob

 @Entity
 public class Employee implements Serializable {
     ...
     @Lob
     @Basic(fetch=LAZY)
     @Column(name="EMP_PIC", columnDefinition="BLOB NOT NULL")
     protected byte[] pic;
     ...
 }

For more information, see Section 11.1.24 "Lob Annotation" in the JPA Specification.

@Temporal	Basic Mappings	@Transient
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