Raible Designs

Enhancing your GWT Application with the UrlRewriteFilter

Last week, I spent some time trying to change the location of my cache/nocache HTML files in my GWT project. I started the project with the gwt-maven-plugin's archetype. The message I posted to the gwt-maven Google Group is below.

Rather than having my application's HTML file in src/main/java/com/mycompany/Application.html, I'd like to move it to src/main/webapp/index.html. I tried copying the HTML and adding the following to my index.html, but no dice:

<meta name="gwt:module" content="com.mycompany.Application"/>

Is this possible with the gwt-maven-plugin? I'd like to have my main HTML and CSS at the root of my application.

The good news is I figured out a solution using the UrlRewriteFilter that 1) allows hosted mode to work as usual and 2) allows your app to be served up from the root URL (/ instead of /com.company.Module/Application.html). Here's the urlrewrite.xml that makes it all possible.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCENGINE urlrewrite PUBLIC "-//tuckey.org//DTD UrlRewrite 3.0//EN"
        "http://tuckey.org/res/dtds/urlrewrite3.0.dtd">

<urlrewrite>
    <rule>
        <from>^/$</from>
        <to type="forward" last="true">/com.mycompany.app.Application/Application.html</to>
    </rule>
    <rule>
        <from>/index.html</from>
        <to type="forward" last="true">/com.mycompany.app.Application/Application.html</to>
    </rule>
    <-- This last rule is necessary for JS and CSS files -->
    <rule>
        <from>^/(.*)\.(.*)$</from>
        <to type="forward">/com.mycompany.app.Application/$1.$2</to>
    </rule>
</urlrewrite>

If you're using the gwt-maven plugin, this file goes in src/main/webapp/WEB-INF. In addition, you'll need to add the following to your web.xml.

    <filter>
        <filter-name>rewriteFilter</filter-name>
        <filter-class>org.tuckey.web.filters.urlrewrite.UrlRewriteFilter</filter-class>
    </filter>

    <filter-mapping>
        <filter-name>rewriteFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>

Finally, add the UrlRewriteFilter dependency in your pom.xml:

    <dependency>
        <groupId>org.tuckey</groupId>
        <artifactId>urlrewritefilter</artifactId>
        <version>3.1.0</version>
    </dependency>

Please let me know if you have any questions.

Update: Jeff posted an alternative configuration that allows you to eliminate the last rule in urlrewrite.xml, as well as use the beloved mvn jetty:run command. To use cleaner WAR packaging and the Jetty plugin, add the following to your pom.xml:

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-war-plugin</artifactId>
    <configuration>
        <webappDirectory>
            ${project.build.directory}/${project.build.finalName}/com.mycompany.app.Application
        </webappDirectory>
    </configuration>
</plugin>
<plugin>
    <groupId>org.mortbay.jetty</groupId>
    <artifactId>maven-jetty-plugin</artifactId>
    <version>6.1.14</version>
    <configuration>
        <webAppConfig>
            <contextPath>/</contextPath>
            <baseResource implementation="org.mortbay.resource.ResourceCollection">
                <resourcesAsCSV>
                    ${basedir}/src/main/webapp,
                    ${project.build.directory}/${project.build.finalName}/com.mycompany.app.Application
                </resourcesAsCSV>
            </baseResource>
        </webAppConfig>
        <scanIntervalSeconds>3</scanIntervalSeconds>
        <scanTargets>
            <scanTarget>${basedir}/src/main/resources</scanTarget>
            <scanTarget>${basedir}/src/main/webapp/WEB-INF</scanTarget>
            <scanTarget>
                ${project.build.directory}/${project.build.finalName}/com.mycompany.app.Application
            </scanTarget>
        </scanTargets>
    </configuration>
</plugin>

Then you can trim your urlrewrite.xml down to:

<urlrewrite>
    <rule>
        <from>^/$</from>
        <to type="forward" last="true">/Application.html</to>
    </rule>
    <rule>
        <from>/index.html</from>
        <to type="forward" last="true">/Application.html</to>
    </rule>
</urlrewrite>

Of course, you could also change the welcome-file in your web.xml or use index.html and the <meta http-equiv="REFRESH"> option. Personally, I have so much affection for the UrlRewriteFilter that I like having it in my project. I'm sure I'll need it someday.

Thanks Jeff!