Compiling JSP pages using ANT

Author: Kasper B. Graversen, 11/12/07 Keywords: ANT, Build script, Compile, JSP, Servlet Abstract: Compiling JSP Code is the right thing to do. It enables you to get compile-time errors rather than run-time errors. It ensures consistency as all the JSP's and Java files can be shipped in one package.

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Compiling JSP pages using ANT

• Since the JSP is only compiled upon viewing, when you upload your JSP you need to view it in order to be 100% sure its error-free. Unless automated, this is tedious and is by all means time consuming
• During compilation the server will seem unresponsive, and worse, if JSP's are uploaded to a live server, changes are that if the JSP's are being accessed during upload a newly uploaded JSP may use another old JSP (if that JSP is in the process of being uploaded or is awaiting to be uploaded). This may lead to some serious inconsistencies which may ripple all the way to the DB and cause long-term head-aches.
• Against the idea of JSP compilation is that it may appear to be easier to just upload single changed JSP files rather than a large big chunk. While the argument may seem valid on the small scale it certainly does not scale up to several installations and many hundreds of JSP files. Especially not if the JSP's are relying on changed java classes.
• The JSP compilation takes care of including Javascript included on pages. However, I have experienced that a weird integration of the FCKEditor did not work with JSP compiling. So be careful when you embark on the path of JSP compilation.

• JSP's are compiled into servlets (target jsp_compile)
• The compiled servlets are mapped in a generated web.xml file (in the argument webXmlFragment="${webapp.path}/WEB-INF/generated_web.xml") and this generated web.xml is merged with the original web.xml with the argument (addWebXmlMappings="true" . This enables the compiled JSP's to be accessed through a URL.
• Servlets and your java code are compiled into classes.
• Finally, it is all wrapped in the .war file.

<!-- path of the web source files -->
<property name="webapp.path" value="." />

<!-- build output name -->
<property name="output_war" value="myapp.war" />

<!-- paths to the Tomcat JSP compiler -->
<property name="catalina.home" value="C:\Programmer\Tomcat 5.5" />

<target name="make_war" depends="compile">
    <description>Harvest the compiled files and html files into a WAR file ready for deployment</description>
    <war destfile="${output_war}" webxml="${webapp.path}/WEB-INF/web.xml">
        <classes dir="${webapp.path}/WEB-INF/classes"/>
        <zipfileset dir="${webapp.path}/graphics/images/" prefix="images"/>
    </war>
</target>


<target name="compile" depends="jsp_compile">
    <description>
    Compile the generated servlets and change web.xml into mapping the servlets to the corresponding .jsp urls.
    </description>

    <mkdir dir="${webapp.path}/WEB-INF/classes"/>
    <mkdir dir="${webapp.path}/WEB-INF/lib"/>

    <javac destdir="${webapp.path}/WEB-INF/classes" srcdir="${webapp.path}/WEB-INF/src" >
        <classpath>
            <pathelement location="${webapp.path}/WEB-INF/classes" />
            <fileset dir="${webapp.path}/WEB-INF/lib">    <include name="*.jar" /></fileset>

            <pathelement location="${catalina.home}/common/classes" />
            <fileset dir="${catalina.home}/common/lib">    <include name="*.jar" /></fileset>

            <pathelement location="${catalina.home}/shared/classes" />
            <fileset dir="${catalina.home}/shared/lib">    <include name="*.jar" /></fileset>

            <fileset dir="${catalina.home}/bin">        <include name="*.jar" /></fileset>
        </classpath>
        <include name="**" />
        <exclude name="tags/**" />
    </javac>
</target>


<target name="jsp_compile" depends="clean_jspcompile">
    <description>Take all .jsp pages and convert them into servlets using the Tomcat jsp compiler</description>
    <taskdef classname="org.apache.jasper.JspC" name="jasper2">
        <classpath id="jspc.classpath">
            <fileset dir="${catalina.home}/bin"><include name="*.jar"/>    </fileset>
            <fileset dir="${catalina.home}/server/lib">    <include name="*.jar"/>    </fileset>
            <fileset dir="${catalina.home}/common/lib">    <include name="*.jar"/>    </fileset>
        </classpath>
    </taskdef>

    <jasper2 uriroot="${webapp.path}"
             webXmlFragment="${webapp.path}/WEB-INF/generated_web.xml"
             addWebXmlMappings="true"
             outputDir="${webapp.path}/WEB-INF/src/" />

              <!-- path to the compiler generated web.xml -->
              <!-- automatically merge the "generated_web.xml" into "web.xml" -->
              <!-- path to the output of the compilation  -->
</target>

<target name="clean_jspcompile">
    <description>clear the generated source files</description>
    <delete dir="${webapp.path}/WEB-INF/src"/>
</target>

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