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Difference between revisions of "Jetty/Howto/Custom Error Pages"

< Jetty‎ | Howto
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==Custom error handler class==
 
==Custom error handler class==
  
A context may be configured with a custom error handler class that extends either [http://dev.eclipse.org/viewcvs/index.cgi/jetty/trunk/jetty-server/src/main/java/org/eclipse/jetty/server/handler/ErrorHandler.java?root=RT_Jetty&view=markup ErrorHandler] for contexts, or [http://dev.eclipse.org/viewcvs/index.cgi/jetty/trunk/jetty-servlet/src/main/java/org/eclipse/jetty/servlet/ErrorPageErrorHandler.java?root=RT_Jetty&view=markup ErrorPageErrorHandler] for webapp contexts.
+
A context may be configured with a custom error handler class that extends either [http://dev.eclipse.org/viewcvs/index.cgi/jetty/trunk/jetty-server/src/main/java/org/eclipse/jetty/server/handler/ErrorHandler.java?root=RT_Jetty&view=markup ErrorHandler] for generic contexts, or [http://dev.eclipse.org/viewcvs/index.cgi/jetty/trunk/jetty-servlet/src/main/java/org/eclipse/jetty/servlet/ErrorPageErrorHandler.java?root=RT_Jetty&view=markup ErrorPageErrorHandler] for webapp contexts.
  
 
The following methods may be implemented to control the appearance of the error pages:
 
The following methods may be implemented to control the appearance of the error pages:

Revision as of 09:30, 10 February 2010



Introduction

There are several ways to create custom error pages in Jetty that are described below.

Define error pages in web.xml

The standard webapp configuration file located in <webapp>/WEB-INF/web.xml can be used to map errors to specific URLs with the <error-page> element. This element creates a mapping between the error-code or exception-type to the location of a resource in the web application.

  • error-code - integer value
  • exception-type - fully qualified class name of a Java Exception type
  • location - location of the resource in webapp relative to the root of the web application. Value should start with "/".

Error code example:

<error-page>
  <error-code>404</error-code>
  <location>/jspsnoop/ERROR/404</location>
</error-page>

Exception example:

<error-page>
  <exception-type>java.io.IOException</exception-type>
  <location>/jspsnoop/IOException</location>
</error-page>

Context file configuration

Context files are normally located in <jetty.home>/contexts/ (see Jetty/Feature/ContextDeployer for more details). Context files can be used to configure the default error handler provided for a context with more flexibility than is available with web.xml, specifically with the support of error code ranges:

<?xml version="1.0"  encoding="ISO-8859-1"?>
<!DOCTYPE Configure PUBLIC "-//Mort Bay Consulting//DTD Configure//EN" "http://jetty.mortbay.org/configure.dtd">
 
<Configure class="org.eclipse.jetty.webapp.WebAppContext">
  <Set name="contextPath">/test</Set>
  <Set name="war">
    <SystemProperty name="jetty.home" default="."/>/webapps/test
  </Set>
 
  <!-- by Code -->
  <Get name="errorHandler">
    <Call name="addErrorPage">
      <Arg type="int">404</Arg>
      <Arg type="String">/jspsnoop/ERROR/404</Arg>
    </Call>
  </Get>
 
  <!-- by Exception -->
  <Get name="errorHandler">
    <Call name="addErrorPage">
      <Arg type="java.lang.Class">java.io.IOException</Arg>
      <Arg type="String">/jspsnoop/IOException</Arg>
    </Call>
  </Get>
 
  <!-- by Code Range -->
  <Get name="errorHandler">
    <Call name="addErrorPage">
      <Arg type="int">500</Arg>
      <Arg type="int">599</Arg>
      <Arg type="String">/dump/errorCodeRangeMapping</Arg>
    </Call>
  </Get>
</Configure>

Custom error handler class

A context may be configured with a custom error handler class that extends either ErrorHandler for generic contexts, or ErrorPageErrorHandler for webapp contexts.

The following methods may be implemented to control the appearance of the error pages:

  • public void handle(String target, HttpServletRequest request, HttpServletResponse response, int dispatch) throws IOException
  • void handleErrorPage(HttpServletRequest request, Writer writer, int code, String message) throws IOException
  • void writeErrorPage(HttpServletRequest request, Writer writer, int code, String message, boolean showStacks) throws IOException
  • void writeErrorPageHead(HttpServletRequest request, Writer writer, int code, String message) throws IOException
  • void writeErrorPageBody(HttpServletRequest request, Writer writer, int code, String message, boolean showStacks) throws IOException
  • void writeErrorPageMessage(HttpServletRequest request, Writer writer, int code, String message,String uri) throws IOException
  • void writeErrorPageStacks(HttpServletRequest request, Writer writer) throws IOException

The custom error handler may be set on the context via the API or via a context configuration file. For example a custom error handling class can be added to the javadoc context with:

<?xml version="1.0"  encoding="ISO-8859-1"?>
<!DOCTYPE Configure PUBLIC "-//Mort Bay Consulting//DTD Configure//EN" "http://jetty.mortbay.org/configure.dtd">
 
<Configure class="org.eclipse.jetty.server.handler.ContextHandler">
  <Call class="org.eclipse.util.log.Log" name="debug"><Arg>Configure javadoc.xml</Arg></Call>
  <Set name="contextPath">/javadoc</Set>
  <Set name="resourceBase"><SystemProperty name="jetty.home" default="."/>/javadoc/</Set>
 
  <!-- Instantiate your own error handler -->
  <Set name="errorHandler">
    <New class="com.acme.handler.MyErrorHandler"/>
  </Set>
 
</Configure>

Server level 404 error

One may get a 'page not found' when a request is made to the server for a resource that is outside of any registered contexts. As an example, you have a domain name pointing to your public server IP yet no context is registered with jetty to serve pages for that domain. As a consequence, the server, by default, will give a listing of all contexts running on the server.

One of the quickest ways to avoid this behavior is to create a catch all context. Create a "root" web app mapped to the "/" URI. Have the index.html redirect to whatever place with a header directive.