docs/custom-injection.adoc

= Custom Injection
:index-group: Unrevised
:jbake-date: 2018-12-05
:jbake-type: page
:jbake-status: published

= Overview

As noted in the link:injection-of-env-entry-example.html[Injection of
env-entry Example] , the EJB 3.0 supported env-entry types are fairly
limited. Also the use of several tags in an ejb-jar.xml can get a bit
verbose.

OpenEJB does not restrict you to just these data types or require you to
use an ejb-jar.xml to declare them.

* `@Resource` can be used on any type for which there is
`java.beans.PropertyEditor`
* You may `install your own` PropertyEditors and package them with your
app.
* Java Generics are supported (e.g. List myURIs)
* You may use a `META-INF/env-entries.properties` file as an alternative
to an ejb-jar.xml

See link:built-in-type-converters.html[Built-in Type Converters] for a
full list of supported env-entry types.

The source for this example is the "custom-injection" directory located
in the link:downloads.html[openejb-examples.zip] available on the
http://tomee.apache.org/downloads.html[download page].

# The Code

== Bean Class

[source,java]
----
@Stateless
public class Stratocaster {

    @Resource(name = "pickups")
    private List<Pickup> pickups;

    @Resource(name = "style")
    private Style style;

    @Resource(name = "dateCreated")
    private Date dateCreated;

    @Resource(name = "guitarStringGuages")
    private Map<String, Float> guitarStringGuages;

    @Resource(name = "certificateOfAuthenticity")
    private File certificateOfAuthenticity;

    public Date getDateCreated() {
        return dateCreated;
    }

    /**
     * Gets the guage of the electric guitar strings
     * used in this guitar.
     *
     * @param string
     * @return
     */
    public float getStringGuage(String string) {
        return guitarStringGuages.get(string);
    }

    public List<Pickup> getPickups() {
        return pickups;
    }

    public Style getStyle() {
        return style;
    }

    public File getCertificateOfAuthenticity() {
        return certificateOfAuthenticity;
    }
}
----

== The META-INF/env-entries.properties file

[source,properties]
----
guitarStringGuages=E1=0.052\nA=0.042\nD=0.030\nG=0.017\nB=0.013\nE=0.010
certificateOfAuthenticity=/tmp/strat-certificate.txt
dateCreated=1962-03-01
pickups=S,S,S
style=VINTAGE
----

== The Custom Type and Editor

Support for java.lang.Enum types is already built-in, but we've decided
we'd like to allow abbreviated versions of the enum constants to be
usable. We do this by creating a custom PropertyEditor for our Pickup
enum like so:

[source,java]
----
public class PickupEditor extends java.beans.PropertyEditorSupport {
    public void setAsText(String text) throws IllegalArgumentException {
        text = text.trim();

        if (text.equalsIgnoreCase("H")) setValue(Pickup.HUMBUCKER);
        else if (text.equalsIgnoreCase("S")) setValue(Pickup.SINGLE_COIL);
        else throw new IllegalStateException("H and S are the only supported Pickup aliases");
    }
}
----

We cleverly install this PropertyEditor in a static block in the Pickup
class that will be executed should someone actually reference the Pickup
type.

[source,java]
----
public enum Pickup {

    HUMBUCKER,
    SINGLE_COIL;

    // Here's the little magic where we register the PickupEditor
    // which knows how to create this object from a string.
    // You can add any of your own Property Editors in the same way.
    static {
        PropertyEditorManager.registerEditor(Pickup.class, PickupEditor.class);
    }
}
----

# Test Case

[source,java]
----
public class StratocasterTest extends TestCase {

    @EJB
    private Stratocaster strat;

    public void test() throws Exception {
        EJBContainer.createEJBContainer().getContext().bind("inject", this);

        Date date = DateFormat.getDateInstance(DateFormat.MEDIUM, Locale.US).parse("Mar 1, 1962");
        assertEquals("Strat.getDateCreated()", date, strat.getDateCreated());

        List<Pickup> pickups = asList(Pickup.SINGLE_COIL, Pickup.SINGLE_COIL, Pickup.SINGLE_COIL);
        assertEquals("Strat.getPickups()", pickups, strat.getPickups());

        assertEquals("Strat.getStyle()", Style.VINTAGE, strat.getStyle());

        assertEquals("Strat.getStringGuage(\"E1\")", 0.052F, strat.getStringGuage("E1"));
        assertEquals("Strat.getStringGuage(\"A\")", 0.042F, strat.getStringGuage("A"));
        assertEquals("Strat.getStringGuage(\"D\")", 0.030F, strat.getStringGuage("D"));
        assertEquals("Strat.getStringGuage(\"G\")", 0.017F, strat.getStringGuage("G"));
        assertEquals("Strat.getStringGuage(\"B\")", 0.013F, strat.getStringGuage("B"));
        assertEquals("Strat.getStringGuage(\"E\")", 0.010F, strat.getStringGuage("E"));

        File file = new File("/tmp/strat-certificate.txt");
        assertEquals("Strat.getCertificateOfAuthenticity()", file,strat.getCertificateOfAuthenticity());


    }
}
----

# Running it

Running the example is fairly simple. In the "custom-injection"
directory of the openejb:download.html[examples zip], just run:

___________________
$ mvn clean install
___________________

Which should create output like the following.

[source,java]
----
-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running org.superbiz.enventries.StratocasterTest
Apache OpenEJB 3.1-SNAPSHOT    build: 20080409-12:05
http://tomee.apache.org/
INFO - openejb.home = /Users/dblevins/work/openejb3/examples/custom-injection
INFO - openejb.base = /Users/dblevins/work/openejb3/examples/custom-injection
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 - Configuring Service(id=Default JDK 1.3 ProxyFactory, type=ProxyFactory, provider-id=Default JDK 1.3 ProxyFactory)
INFO - Found EjbModule in classpath: /Users/dblevins/work/openejb3/examples/custom-injection/target/classes
INFO - Configuring app: /Users/dblevins/work/openejb3/examples/custom-injection/target/classes
INFO - Configuring Service(id=Default Stateless Container, type=Container, provider-id=Default Stateless Container)
INFO - Auto-creating a container for bean StratocasterImpl: Container(type=STATELESS, id=Default Stateless Container)
INFO - Loaded Module: /Users/dblevins/work/openejb3/examples/custom-injection/target/classes
INFO - Assembling app: /Users/dblevins/work/openejb3/examples/custom-injection/target/classes
INFO - Jndi(name=StratocasterImplLocal) --> Ejb(deployment-id=StratocasterImpl)
INFO - Created Ejb(deployment-id=StratocasterImpl, ejb-name=StratocasterImpl, container=Default Stateless Container)
INFO - Deployed Application(path=/Users/dblevins/work/openejb3/examples/custom-injection/target/classes)
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 0.705 sec

Results :

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