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Using EnvEntries

The @Resource annotation can be used to inject several things including DataSources, Topics, Queues, etc. Most of these are container supplied objects.

It is possible, however, to supply your own values to be injected via an <env-entry> in your ejb-jar.xml or web.xml deployment descriptor. Java EE 6 supported <env-entry> types are limited to the following:

  • java.lang.String
  • java.lang.Integer
  • java.lang.Short
  • java.lang.Float
  • java.lang.Double
  • java.lang.Byte
  • java.lang.Character
  • java.lang.Boolean
  • java.lang.Class
  • java.lang.Enum (any enum)

See also the Custom Injection exmaple for a TomEE and OpenEJB feature that will let you use more than just the above types as well as declare <env-entry> items with a plain properties file.

Using @Resource for basic properties

The use of the @Resource annotation isn't limited to setters. For example, this annotation could have been used on the corresponding field like so:

@Resource
private int maxLineItems;

A fuller example might look like this:

package org.superbiz.injection.enventry;

import javax.annotation.Resource;
import javax.ejb.Singleton;
import java.util.Date;

@Singleton
public class Configuration {

    @Resource
    private String color;

    @Resource
    private Shape shape;

    @Resource
    private Class strategy;

    @Resource(name = "date")
    private long date;

    public String getColor() {
        return color;
    }

    public Shape getShape() {
        return shape;
    }

    public Class getStrategy() {
        return strategy;
    }

    public Date getDate() {
        return new Date(date);
    }
}

Here we have an @Singleton bean called Confuration that has the following properties (<env-entry> items)

  • String color
  • Shape shape
  • Class strategy
  • long date

Supplying @Resource values for items in ejb-jar.xml

The values for our color, shape, strategy and date properties are supplied via <env-entry> elements in the ejb-jar.xml file or the
web.xml file like so:

<ejb-jar xmlns="http://java.sun.com/xml/ns/javaee" version="3.0" metadata-complete="false">
  <enterprise-beans>
    <session>
      <ejb-name>Configuration</ejb-name>
      <env-entry>
        <env-entry-name>org.superbiz.injection.enventry.Configuration/color</env-entry-name>
        <env-entry-type>java.lang.String</env-entry-type>
        <env-entry-value>orange</env-entry-value>
      </env-entry>
      <env-entry>
        <env-entry-name>org.superbiz.injection.enventry.Configuration/shape</env-entry-name>
        <env-entry-type>org.superbiz.injection.enventry.Shape</env-entry-type>
        <env-entry-value>TRIANGLE</env-entry-value>
      </env-entry>
      <env-entry>
        <env-entry-name>org.superbiz.injection.enventry.Configuration/strategy</env-entry-name>
        <env-entry-type>java.lang.Class</env-entry-type>
        <env-entry-value>org.superbiz.injection.enventry.Widget</env-entry-value>
      </env-entry>
      <env-entry>
        <description>The name was explicitly set in the annotation so the classname prefix isn't required</description>
        <env-entry-name>date</env-entry-name>
        <env-entry-type>java.lang.Long</env-entry-type>
        <env-entry-value>123456789</env-entry-value>
      </env-entry>
    </session>
  </enterprise-beans>
</ejb-jar>

Using the @Resource 'name' attribute

Note that date was referenced by name as:

@Resource(name = "date")
private long date;

When the @Resource(name) is used, you do not need to specify the full class name of the bean and can do it briefly like so:

  <env-entry>
    <description>The name was explicitly set in the annotation so the classname prefix isn't required</description>
    <env-entry-name>date</env-entry-name>
    <env-entry-type>java.lang.Long</env-entry-type>
    <env-entry-value>123456789</env-entry-value>
  </env-entry>

Conversly, color was not referenced by name

@Resource
private String color;

When something is not referenced by name in the @Resource annotation a default name is created. The format is essentially this:

bean.getClass() + "/" + field.getName()

So the default name of the above color property ends up being org.superbiz.injection.enventry.Configuration/color. This is the name we must use when we attempt to decalre a value for it in xml.

  <env-entry>
    <env-entry-name>org.superbiz.injection.enventry.Configuration/color</env-entry-name>
    <env-entry-type>java.lang.String</env-entry-type>
    <env-entry-value>orange</env-entry-value>
  </env-entry>

@Resource and Enum (Enumerations)

The shape field is actually a custom Java Enum type

package org.superbiz.injection.enventry;

public enum Shape {

    CIRCLE,
    TRIANGLE,
    SQUARE
}

As of Java EE 6, java.lang.Enum types are allowed as <env-entry> items. Declaring one in xml is done using the actual enum's class name like so:

      <env-entry>
        <env-entry-name>org.superbiz.injection.enventry.Configuration/shape</env-entry-name>
        <env-entry-type>org.superbiz.injection.enventry.Shape</env-entry-type>
        <env-entry-value>TRIANGLE</env-entry-value>
      </env-entry>

Do not use <env-entry-type>java.lang.Enum</env-entry-type> or it will not work!

ConfigurationTest

package org.superbiz.injection.enventry;

import junit.framework.TestCase;

import javax.ejb.embeddable.EJBContainer;
import javax.naming.Context;
import java.util.Date;

public class ConfigurationTest extends TestCase {


    public void test() throws Exception {
        final Context context = EJBContainer.createEJBContainer().getContext();

        final Configuration configuration = (Configuration) context.lookup("java:global/injection-of-env-entry/Configuration");

        assertEquals("orange", configuration.getColor());

        assertEquals(Shape.TRIANGLE, configuration.getShape());

        assertEquals(Widget.class, configuration.getStrategy());

        assertEquals(new Date(123456789), configuration.getDate());
    }
}

Running

-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running org.superbiz.injection.enventry.ConfigurationTest
Apache OpenEJB 4.0.0-beta-1    build: 20111002-04:06
http://tomee.apache.org/
INFO - openejb.home = /Users/dblevins/examples/injection-of-env-entry
INFO - openejb.base = /Users/dblevins/examples/injection-of-env-entry
INFO - Using 'javax.ejb.embeddable.EJBContainer=true'
INFO - Configuring Service(id=Default Security Service, type=SecurityService, provider-id=Default Security Service)
INFO - Configuring Service(id=Default Transaction Manager, type=TransactionManager, provider-id=Default Transaction Manager)
INFO - Found EjbModule in classpath: /Users/dblevins/examples/injection-of-env-entry/target/classes
INFO - Beginning load: /Users/dblevins/examples/injection-of-env-entry/target/classes
INFO - Configuring enterprise application: /Users/dblevins/examples/injection-of-env-entry
WARN - Method 'lookup' is not available for 'javax.annotation.Resource'. Probably using an older Runtime.
INFO - Configuring Service(id=Default Singleton Container, type=Container, provider-id=Default Singleton Container)
INFO - Auto-creating a container for bean Configuration: Container(type=SINGLETON, id=Default Singleton Container)
INFO - Configuring Service(id=Default Managed Container, type=Container, provider-id=Default Managed Container)
INFO - Auto-creating a container for bean org.superbiz.injection.enventry.ConfigurationTest: Container(type=MANAGED, id=Default Managed Container)
INFO - Enterprise application "/Users/dblevins/examples/injection-of-env-entry" loaded.
INFO - Assembling app: /Users/dblevins/examples/injection-of-env-entry
INFO - Jndi(name="java:global/injection-of-env-entry/Configuration!org.superbiz.injection.enventry.Configuration")
INFO - Jndi(name="java:global/injection-of-env-entry/Configuration")
INFO - Jndi(name="java:global/EjbModule1355224018/org.superbiz.injection.enventry.ConfigurationTest!org.superbiz.injection.enventry.ConfigurationTest")
INFO - Jndi(name="java:global/EjbModule1355224018/org.superbiz.injection.enventry.ConfigurationTest")
INFO - Created Ejb(deployment-id=org.superbiz.injection.enventry.ConfigurationTest, ejb-name=org.superbiz.injection.enventry.ConfigurationTest, container=Default Managed Container)
INFO - Created Ejb(deployment-id=Configuration, ejb-name=Configuration, container=Default Singleton Container)
INFO - Started Ejb(deployment-id=org.superbiz.injection.enventry.ConfigurationTest, ejb-name=org.superbiz.injection.enventry.ConfigurationTest, container=Default Managed Container)
INFO - Started Ejb(deployment-id=Configuration, ejb-name=Configuration, container=Default Singleton Container)
INFO - Deployed Application(path=/Users/dblevins/examples/injection-of-env-entry)
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 1.664 sec

Results :

Tests run: 1, Failures: 0, Errors: 0, Skipped: 0