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Chapter 17. Handlers

Table of Contents

Rewrite Handler
Writing Custom Handlers

Rewrite Handler

The RewriteHandler matches a request against a set of rules, and modifies the request accordingly for any rules that match. The most common use is to rewrite request URIs, but it is capable of much more: rules can also be configured to redirect the response, set a cookie or response code on the response, modify the header, etc.

Quick Start

The standard Jetty distribution bundle contains the jetty-rewrite module JAR, at lib/jetty-rewrite-*.jar, and a sample configuration file, at etc/jetty-rewrite.xml. To enable the rewrite module, using the sample configuration file, start up Jetty with this command:


$ java -jar start.jar OPTIONS=default,rewrite etc/jetty.xml etc/jetty-rewrite.xml 

    

Note

If you are running the standard Jetty distribution with the sample test webapp, there will be a demo of the rewrite module at http://localhost:8080/rewrite/

Configuring Rules

The rules are configured using jetty.xml syntax. This example file shows how to add the rewrite handler for the entire server:

<Configure id="Server" class="org.eclipse.jetty.server.Server">
    <!-- create and configure the rewrite handler -->
    <New id="Rewrite" class="org.eclipse.jetty.rewrite.handler.RewriteHandler">
      <Set name="rewriteRequestURI">true</Set>
      <Set name="rewritePathInfo">false</Set>
      <Set name="originalPathAttribute">requestedPath</Set>
 
      <!-- redirect the response. This is a redirect which is visible to the browser.
           After the redirect, the browser address bar will show /redirected -->
      <Call name="addRule">
        <Arg>
          <New class="org.eclipse.jetty.rewrite.handler.RedirectPatternRule">
            <Set name="pattern">/redirect/*</Set>
            <Set name="replacement">/redirected</Set>
          </New>
        </Arg>
      </Call>
 
      <!-- rewrite the request URI. This is an internal rewrite, visible to server,
           but the browser will still show /some/old/context -->
      <Call name="addRule">
        <Arg>
          <New class="org.eclipse.jetty.rewrite.handler.RewritePatternRule">
            <Set name="pattern">/some/old/context</Set>
            <Set name="replacement">/some/new/context</Set>
          </New>
        </Arg>
      </Call>
 
      <!-- reverse the order of the path sections. Internal rewrite -->
      <Call name="addRule">
        <Arg>
          <New class="org.eclipse.jetty.rewrite.handler.RewriteRegexRule">
            <Set name="regex">/reverse/([^/]*)/(.*)</Set>
            <Set name="replacement">/reverse/$2/$1</Set>
          </New>
        </Arg>
      </Call>
    </New>
 
     <!-- add the rewrite handler to the server -->
    <Set name="handler"><Ref id="Rewrite" /></Set>
</Configure>

      

See etc/jetty-rewrite.xml for more configuration examples.

Embedded Example

This is an example for embedded Jetty, which does the same thing as the configuration file example above:


  Server server = new Server();
 
  RewriteHandler rewrite = new RewriteHandler();
  rewrite.setRewriteRequestURI(true);
  rewrite.setRewritePathInfo(false);
  rewrite.originalPathAttribute("requestedPath");
 
  RedirectPatternRule redirect = new RedirectPatternRule();
  redirect.setPattern("/redirect/*");
  redirect.setReplacement("/redirected");  
  rewrite.addRule(redirect);
 
  RewritePatternRule oldToNew = new RewritePatternRule();
  oldToNew.setPattern("/some/old/context");
  oldToNew.setReplacement("/some/new/context");
  rewrite.addRule(oldToNew);
 
  RewriteRegexRule reverse = new RewriteRegexRule();
  reverse.setRegex("/reverse/([^/]*)/(.*)");
  reverse.setReplacement("/reverse/$2/$1");
  rewrite.addRule(reverse);
 
  server.setHandler(rewrite);
  
      

Rules

There are several types of rules that are written extending useful base rule classes.

PatternRule

Matches against the request URI using the servlet pattern syntax.

CookiePatternRule

Adds a cookie to the response.

HeaderPatternRule

Adds/modifies a header in the response.

RedirectPatternRule

Redirects the response.

ResponsePatternRule

Sends the response code (status or error).

RewritePatternRule

Rewrite the URI by replacing the matched request path with a fixed string.

RegexRule

Matches against the request URI using regular expressions.

RedirectRegexRule

Redirect the response.

RewriteRegexRule

Rewrite the URI by matching with a regular expression. (The replacement string may use Template:$n to replace the nth capture group.)

HeaderRule

Match against request headers. Match either on a header name + specific value, or on the presence of a header (with any value).

ForwardedSchemaHeaderRule

Set the scheme on the request (defaulting to https).

Others

Oddball rules that defy classification.

MsieSslRule

Disables the keep alive for SSL from IE5 or IE6.

LegacyRule

Implements the legacy API of RewriteHandler

RuleContainer

Groups rules together. The contained rules will only be processed if the conditions for the RuleContainer evaluate to true.

VirtualHostRuleContainer

Groups rules that apply only to a specific virtual host or a set of virtual hosts

See an error or something missing? Contribute to this documentation at Github!