JSP compilation causes the compilation of JSP files before they are first accessed on a live server.

JspPrecompileListener

Unless explicitly compiled ahead of time, JSP files are compiled the first time they are accessed. On large production sites, or in situations involving complicated JSP files, compilation may cause unacceptable delays to users first accessing the JSP page.

Resin provides a JspPrecompileListener that causes jsp to be compiled when the web application starts. As an alternative, Resin also provides a JspCompiler that is used to explicitly compile jsp files before they are accessed for the first time.

com.caucho.jsp.JspPrecompileListener is a ServletContextListener that compiles jsp files when the web-app starts. It is activated using the <listener> Servlet configuration tag in web.xml.

The following configuration causes Resin to compile all files in the web-app that have an extension of .jsp or .jspx when the application first starts.

<web-app xmlns="http://caucho.com/ns/resin">
  <listener>
    <listener-class>com.caucho.jsp.JspPrecompileListener</listener-class>
    <init>
      <extension>jsp</extension>
      <extension>jspx</extension>
    </init>
  </listener>
</web-app>

It can also be configured in resin.conf to apply to all web-app's.

<web-app-default>
  <listener>
    <listener-class>com.caucho.jsp.JspPrecompileListener</listener-class>
    <init>
      <extension>jsp</extension>
      <extension>jspx</extension>
      <extension>xtp</extension>
    </init>
  </listener>
</web-app-default>

You can also use a fileset for more control over which jsp are precompiled:

<web-app>
  <listener>
    <listener-class>com.caucho.jsp.JspPrecompileListener</listener-class>
    <init>
      <fileset>
        <include>**/*.jsp</include>
        <exclude>/a.jsp</exclude>
        <exclude>/foo/c.jsp</exclude>
      </fileset>
    </init>
  </listener>
</web-app>

The first line includes all jsp's, it's the same as specifying jsp. The following lines exclude specific jsp.

JspCompiler

com.caucho.jsp.JspCompiler is used to compile JSP.

Command line usage of JspCompile

Command line usage accepts arguments that correspond to the parameters available to the parameters of the JSpCompiler class.

unix> java com.caucho.jsp.JspCompiler -app-dir "/opt/www/foo" test/foo.jsp

com.caucho.jsp.JspCompiler accepts a -conf argument, which points to a web-app configuration.

  
<web-app xmlns="http://caucho.com/ns/resin">
  <document-directory>/opt/www/foo</document-directory>
    
  <resin:import path="/opt/resin/conf/app-default.xml"/>
</web-app>

unix> java com.caucho.jsp.JspCompiler -conf /opt/resin/compile-app.xml" test/foo.jsp