XML Declaration Generation
When the container processes a JSP Document, it adds an XML declaration like this to the response in most cases:
<? xml version="1.0" encoding="encodingValue
" ?>
The encoding
attribute value is the response
character encoding defined by a page
directive
with a contentType
attribute containing a
character encoding, as described in Chapter 14, or
UTF-8 if it’s not defined in the JSP Document.
The XML declaration is generated by default for a JSP Document,
unless <jsp:root>
is used as the root
element. You can use the <jsp:output>
standard action to suppress the generation of the declaration, or to
force it to be generated for a <jsp:root>
document:
<jsp:output omit-xml-declaration="true" />
The omit-xml-declaration
attribute accepts one of
four values: with the value true
or
yes
, the declaration is not generated; if set to
false
or no
, it is. A reason to
omit the declaration is when the generated response is included into
another document, for instance using the
<jsp:include>
action in another JSP
Document.
For tag files written in XML syntax, no XML declaration is generated
by default, since their output typically gets mixed with the content
of the page that invokes them. In the rare event you need one, you
can use the <jsp:output>
action in the tag
file with omit-xml-declaration
set to
false
or no
.
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