The Java Tutorials have been written for JDK 8. Examples and practices described in this page don't take advantage of improvements introduced in later releases and might use technology no longer available.
See Java Language Changes for a summary of updated language features in Java SE 9 and subsequent releases.
See JDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.
Long-term persistence is a model that enables beans to be saved in XML format.
Information on the XML format and on how to implement long-term persistence for non-beans can be found in XML Schema and Using XMLEncoder.
The
XMLEncoder
class is assigned to write output files for textual representation of Serializable
objects. The following code fragment is an example of writing a Java bean and its properties in XML format:
XMLEncoder encoder = new XMLEncoder( new BufferedOutputStream( new FileOutputStream("Beanarchive.xml"))); encoder.writeObject(object); encoder.close();
The
XMLDecoder
class reads an XML document that was created with XMLEncoder:
XMLDecoder decoder = new XMLDecoder( new BufferedInputStream( new FileInputStream("Beanarchive.xml"))); Object object = decoder.readObject(); decoder.close();
An XML bean archive has its own specific syntax, which includes the following tags to represent each bean element:
<java>
tag to embody all object elements of the bean<object>
tag to represent a set of method calls needed to reconstruct an object from its serialized form
<object class="javax.swing.JButton" method="new"> <string>Ok</string> </object>
<object class="javax.swing.JButton"> <void method="setText"> <string>Cancel</string> </void> </object>
<boolean>
<byte>
<char>
<short>
<int>
<long>
<float>
<double>
<int>5555</int>
class
> tag to represent an instance of Class.
<class>java.swing.JFrame</class>
array
> tag to define an array
<array class="java.lang.String" length="5"> </array>
The following code represents an XML archive that will be generated for the SimpleBean
component:
<?xml version="1.0" encoding="UTF-8" ?> <java> <object class="javax.swing.JFrame"> <void method="add"> <object class="java.awt.BorderLayout" field="CENTER"/> <object class="SimpleBean"/> </void> <void property="defaultCloseOperation"> <object class="javax.swing.WindowConstants" field="DISPOSE_ON_CLOSE"/> </void> <void method="pack"/> <void property="visible"> <boolean>true</boolean> </void> </object> </java>