EL Variables

host regexp

<host regexp="www.([^.]+).com"> <root-directory>/opt/www/${host.regexp[1]}</root-directory> <document-directory>${host.rootDir}/doc</document-directory> <context-param server-id="${server.name}"/> </host>

Special variables
variable attribute meaning

Var System properties, e.g. ${Var["resin.home"]}

server Server properties

name The server id, as specified in -server id

rootDir The server root directory, $SERVER_ROOT

docDir The server document directory

host Virtual host properties

url The host's canonical URL

name The host name

rootDir The host's root directory

docDir The host's document directory

warDir The host's war directory

warExpandDir The host's war expansion directory

regexp Regular expression values for host regexp matches

app web-app properties

url The web-app's canonical URL

name The web-app name

contextPath The web-app's context path

docDir The web-app's document directory

regexp Regular expression values for web-app url-regexp matches

jndi:lookup

The configuration EL supports a single static function: jndi:lookup. jndi:lookup can be used to lookup a JNDI value for the configuration.

configuring JNDI

<servlet servlet-name='foo' servlet-class='qa.FooServlet'> <init> <data-source>${jndi:lookup("java:comp/env/jdbc/test")}</data-source> </init> </servlet>

Servlet/Filter bean-style initialization 2.1.3

EL expressions can be used to configure servlets and filters. init-param values can use JSP EL expressions, including the ability to use system properties. Servlets and filters can be configured like beans, i.e. having setter methods called directly.

One main use for the bean-style servlet initialization is to avoid JNDI lookup inside the servlet code. For example, a servlet that that uses a JDBC DataSource might look like:

Servlet using JDBC

package test; ... public class TestServlet extends HttpServlet { private DataSource _dataSource; /** * Bean setter is called to configure the servlet * before the init() method. */ public void setDataSource(DataSource dataSource) { _dataSource = dataSource; } ... }

The servlet could be configured as follows:

Example configuration

<web-app> <allow-servlet-el/> <servlet servlet-name='test' servlet-class='test.TestServlet'> <init> <data-source>${jndi:lookup("java:comp/env/jdbc/test")}</data-source> </init> </servlet> ... </web-app>

log

Configuration

init