JavaBeans Activation Framework
Introduction
In computer programming, JavaBeans Activation Framework, or JAF, enables developers to:[1]
- determine the type of an arbitrary piece of data,
- encapsulate access to it,
- discover the operations available on it and
- to instantiate the appropriate bean to perform the operation(s).
It also enables you to dynamically register types of arbitrary data and actions associated with particular kinds of data. Additionally, it enables a program to dynamically provide or retrieve JavaBeans that implement actions associated with some kind of data.
- JSR-925
- Latest spec version is 1.1
- It's an old spec released on April 2006
- It's originally an extension API
- Now available as a standard API in Java SE and Java EE
- Has only one package javax.activation (4 interfaces, 13 classes)
Datasource Interface
- Provides access to an arbitrary collection of data
- Get name of the data, data-type name (content type), and the data itself asInputStream or OutputStream
- Two implementation classes provided
- URLDataSource simplifies the handling of data described by URLs
- FileDataSource simple DataSource object that encapsulates a file provides data typing services -> delegated to a FileTypeMap object.
- Other implementation
- javax.mail.internet.MimePartDataSource
DataContentHandler interface
- Convert the object to a byte stream and write it to the output stream
- Convert streams in to objects
- Used to get object/data which can be transferred
- Uses java.awt.datatransfer.DataFlavor to indicate the data that can be accessed. DataFlavor is a data format as would appear on a clipboard, during drag and drop, or in a file system.
CommandMap class
- An abstract class provides an interface to a registry of command objects available in the system
- Developer develop their own implementation or use
- MailcapCommandMap class that implements a CommandMap whose configuration is based on mailcap files (1524)
- Command list available from a MIME Type is stored in CommandInfo object.
CommandObject interface
- Interface to be implemented by JavaBeans components that are ActivationFramework aware
- Simple interface with one method:
- setCommandContext(String verb, DataHandler dh)
Example: Compose an e-mail with attachment
import javax.activation.DataHandler;
import javax.activation.FileDataSource;
import javax.mail.internet.*;
import javax.mail.*;
...
// Create a message.
MimeMessage message = new MimeMessage(session);
...
// Create the Multipart to be added the parts to
Multipart multipart= new MimeMultipart();
// Create and fill the first text message part
MimeBodyPart mbp = new MimeBodyPart();
mbp.setText(Body);
multipart.addBodyPart(mbp);
// Create a file attachment and fill as second message part
MimeBodyPart mbp = new MimeBodyPart();
FileDataSource fds = new FileDataSource(“C:attachment.zip”);
mbp.setDataHandler(new DataHandler(fds));
mbp.setFileName(fds.getName());
multipart.addBodyPart(mbp);
// Add the multipart to the message
message.setContent(multipart);
...
JAF in use
- REST easy with the JavaBeans Activation Framework
- Example also available in Java' 6™ New Features: A Tutorial' book, chapter-13 ISBN 0-9752128-8-5
- Other presentation deck: http://www.hilbertinc.com/whitepapers/JAF.pdf
External links
- JSR 925: JavaBeans™ Activation Framework 1.1 Specification
- JavaBeans Activation Framework official page
- Introduction to JavaBeans Activation Framework
- http://www.javaworld.com/javaworld/jw-10-2007/jw-10-resteasy.html''
- http://www.hilbertinc.com/whitepapers/JAF.pdf
References
- ↑ JavaBeans Activation Framework. Retrieved 2013-08-11.
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