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Miscellaneous Tags

<< URL Tags | XML Tag Library >>
<< URL Tags | XML Tag Library >>

Miscellaneous Tags

Miscellaneous Tags
The catch tag provides a complement to the JSP error page mechanism. It allows page authors
to recover gracefully from error conditions that they can control. Actions that are of central
importance to a page should not be encapsulated in a catch; in this way their exceptions will
propagate instead to an error page. Actions with secondary importance to the page should be
wrapped in a catch so that they never cause the error page mechanism to be invoked.
The exception thrown is stored in the variable identified by var, which always has page scope. If
no exception occurred, the scoped variable identified by var is removed if it existed. If var is
missing, the exception is simply caught and not saved.
The out tag evaluates an expression and outputs the result of the evaluation to the current
JspWriter
object. The syntax and attributes are as follows:
<c:out value=
"value" [escapeXml="{true|false}"]
[default=
"defaultValue"] />
If the result of the evaluation is a java.io.Reader object, then data is first read from the Reader
object and then written into the current JspWriter object. The special processing associated
with Reader objects improves performance when a large amount of data must be read and then
written to the response.
If escapeXml is true, the character conversions listed in
Table 7­3
are applied.
TABLE 7­3
Character Conversions
Character
Character Entity Code
<
&lt;
>
&gt;
&
&amp;
'
&#039;
"
&#034;
XML Tag Library
The JSTL XML tag set is listed in
Table 7­4
.
XML Tag Library
Chapter 7 · JavaServer Pages Standard Tag Library
211