ExpressionFactory

Introduction

Implementation of a javax.naming.spi.ObjectFactory for any Resource that can be computed from an EL 3.0 expression (JSR-341).

This factory can be configured in a <DefaultContext> or <Context> element in your tomcat 8.0.0-RC3+ conf/server.xml configuration file.

Usage

<Resource
  name="some/jndi/name"
  type="fully.qualified.class.name"
  factory="org.apache.naming.factory.ExpressionFactory"
  importClass="list.of.classes, which.will.be.used, in.the.expression"
  importPackage="list.of.packages, which.will.be.used, in.the.expression"
  importStatic="list.of.static.methods, which.will.be.used, in.the.expression"
  expression="your EL 3.0 expression"
/>

Properties

Name	Presence	Description
name	required	The local JNDI name where the result will be bound
factory	required	Must be org.apache.naming.factory.ExpressionFactory
expression	required	The EL 3.0 expression whose result will be returned by the ObjectFactory.getInstance() method
type	required?	The result type of the EL expression
importClass	optional	Which classes should be imported to the ELProcessor. Use FQCN separated by spaces or commas
importPackage	optional	Which packages should be imported to the ELProcessor. Use FQPN separated by spaces or commas
importStatic	optional	Which static methods should be imported to the ELProcessor. Use FQMN separated by spaces or commas

Examples

Creating an URL resource

In web.xml:

<resource-ref>
  <res-ref-name>url/SomeService</res-ref-name>
  <res-type>java.net.URL</res-type>
  <res-auth>Container</res-auth>
  <res-sharing-scope>Shareable</res-sharing-scope>
</resource-ref>

In context.xml or server.xml:

<Resource
  name="url/SomeService"
  type="java.net.URL"
  factory="org.apache.naming.factory.ExpressionFactory"
  importClass="java.net.URI"
  expression="URI('http://some.service.url').toURL()"
/>

Creating an EHCache CacheManager Resource with a configuration file relative to $CATALINA_BASE

In web.xml:

<resource-ref>
  <res-ref-name>cache/CacheManager</res-ref-name>
  <res-type>net.sf.ehcache.CacheManager</res-type>
  <res-auth>Container</res-auth>
  <res-sharing-scope>Shareable</res-sharing-scope>
</resource-ref>

In context.xml or server.xml:

<Resource
  name="cache/CacheManager"
  type="net.sf.ehcache.CacheManager"
  factory="org.apache.naming.factory.ExpressionFactory"
  importClass="net.sf.ehcache.CacheManager,java.net.URI"
  importStatic="net.sf.ehcache.CacheManager.newInstance"
  expression="CacheManager.newInstance(URI('file:${catalina.base}/conf/ehcache.xml').toURL())"
  closeMethod="shutdown"
  singleton="true"
/>