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.
External Resources
XML, Schema, and XSLT standards support the following constructs that require external resources. The default behavior of the JDK XML processors is to make a connection and fetch the external resources as specified.
- External DTD: references an external Document Type Definition (DTD), example: <!DOCTYPE root_element SYSTEM "url">
- External Entity Reference: refer to external data, syntax: <!ENTITY name SYSTEM "url">
General entity reference such as the following:
<?xml version="1.0" standalone="no" ?>
<!DOCTYPE doc [<!ENTITY otherFile SYSTEM "otherFile.xml">]>
<doc>
<foo>
<bar>&otherFile;</bar>
</foo>
</doc>
- External Parameter Entities, syntax <!ENTITY % name SYSTEM uri>. For example:
<?xml version="1.0" standalone="no"?>
<!DOCTYPE doc [
<!ENTITY % foo SYSTEM "http://www.example.com/student.dtd"<
%foo;
]>
- XInclude: include an external infoset in an XML document
- Reference to XML Schema components using schemaLocation attribute, and import and include elements. Example: schemaLocation="http://www.example.com/schema/bar.xsd"
- Combining style sheets using import or include elements: syntax: <xsl:include href="include.xsl"/>
- xml-stylesheet processing instruction: used to include a stylesheet in an xml document, syntax: <?xml-stylesheet href="foo.xsl" type="text/xsl"?>
- XSLT document() function: used to access nodes in an external XML document. For example, <xsl:variable name="dummy" select="document('DocumentFunc2.xml')"/>.