| <html><head> | |
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| <title>2.9. Error Handling</title><link rel="stylesheet" href="css/stylesheet.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.75.0"><link rel="home" href="index.html" title="Apache Click"><link rel="up" href="ch02.html" title="Chapter 2. Pages"><link rel="prev" href="ch02s08.html" title="2.8. Stateful Pages"><link rel="next" href="ch02s10.html" title="2.10. Page Not Found"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">2.9. Error Handling</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ch02s08.html">Prev</a> </td><th width="60%" align="center">Chapter 2. Pages</th><td width="20%" align="right"> <a accesskey="n" href="ch02s10.html">Next</a></td></tr></table><hr></div><div class="sect1" title="2.9. Error Handling"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="page-error-handling"></a>2.9. Error Handling</h2></div></div></div><p>If an Exception occurs processing a Page object or rendering a | |
| template the error is delegated to the registered handler. The default | |
| Click error handler is the | |
| <a xmlns:fo="http://www.w3.org/1999/XSL/Format" class="external" href="../../click-api/org/apache/click/util/ErrorPage.html" target="_blank">ErrorPage</a>, | |
| which is automatically configured as: | |
| </p><div class="literallayout"><p><page path="<code class="varname">click/error.htm</code>" classname="<span class="symbol">org.apache.click.util.ErrorPage</span>"/></p></div><p>To register an alternative error handler you must subclass ErrorPage | |
| and define your page using the path <code class="varname">"click/error.htm"</code>. | |
| For example: | |
| </p><div class="literallayout"><p><page path="<code class="varname">click/error.htm</code>" classname="<span class="symbol">com.mycorp.page.ErrorPage</span>"/></p></div><p>When the ClickSevlet starts up it checks to see whether the | |
| <code class="varname">error.htm</code> template exists in the <code class="varname">click</code> | |
| web sub directory. If it cannot find the page the ClickServlet will | |
| automatically deploy one. You can tailor the <code class="varname">click/error.htm</code> | |
| template to suite you own tastes, and the ClickServlet will | |
| not overwrite it. | |
| </p><p>The default error template will display extensive debug information | |
| when the application is in <code class="literal">development</code> or | |
| <code class="literal">debug</code> mode. Example error page displays include: | |
| </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p> | |
| <a xmlns:fo="http://www.w3.org/1999/XSL/Format" class="external" href="../../error-npe.html" target="_blank">NullPointerException</a> - in a page | |
| method | |
| </p></li><li class="listitem"><p> | |
| <a xmlns:fo="http://www.w3.org/1999/XSL/Format" class="external" href="../../error-parsing.html" target="_blank">ParseErrorException</a> - in a | |
| page template | |
| </p></li></ul></div><p>When the application is in <code class="literal">production</code> mode only | |
| a simple error message is displayed. See | |
| <a class="link" href="ch04s02.html#application-mode" title="4.2.6. Mode">Configuration</a> for details on how to | |
| set the application mode. | |
| </p><p>Please also see the <a xmlns:fo="http://www.w3.org/1999/XSL/Format" class="external" href="../../examples.html" target="_blank">Examples</a> web | |
| app Exception Demo for demonstrations of Clicks error handling. | |
| </p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ch02s08.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ch02.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ch02s10.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">2.8. Stateful Pages </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> 2.10. Page Not Found</td></tr></table></div></body></html> |