= CDI Field Producer
:index-group: CDI
:jbake-type: page
:jbake-status: published

Este exemplo mostra o uso da anotação `@Produces`. `@Produces` é um mecanismo do CDI que permite definir uma fonte para injeção. Este exemplo mostra uma das duas formas de declarar um producer. Ao invés de um produces method (veja no exemplo CDI-produces-disposes), um producer field pode ser usado. Um producer field pode ser usado ao invés de um simples método getter. Isso pode ser usado para injetar recursos como, contexto de persistência. Uma ressalva para o uso de produces fields sobre produces method é que um método `@Disposes` não pode ser usado junto de um `@Produces` field.

Para o proposito deste exemplo, `type` é hard-coded em um valor especifico. Uma implementação de Logger deve conter uma lista de LogHandlers. Nós devemos ter três implementações da interface LogHandler.

* Uma DatabaseHandler
* Uma FileHandler
* Uma ConsoleHandler

A implementação DatabaseHandler aparentemente gravaria os logs em um banco de dados. O FileHandler gravaria os mesmos logs em um arquivo. E o ConsoleHandler apenas imprimiria os logs no console. Este exemplo é apenas uma ilustração de como os conceitos dentro do CDI funcionam e não tem a intenção de fornecer uma implementação/design de estrutura de log. 

== ConsoleHandler

....
package org.superbiz.cdi.produces.field;

public class ConsoleHandler implements LogHandler {

    private String name;

    public ConsoleHandler(String name) {
        this.name = name;
    }

    @Override
    public String getName() {
        return name;
    }

    @Override
    public void writeLog(String s) {
        System.out.printf("##### Handler: %s, Writing to the console!\n", getName());
    }
}
....

== DatabaseHandler

....
package org.superbiz.cdi.produces.field;

public class DatabaseHandler implements LogHandler {

    private String name;

    public DatabaseHandler(String name) {
        this.name = name;
    }

    @Override
    public String getName() {
        return name;
    }

    @Override
    public void writeLog(String s) {
        System.out.printf("##### Handler: %s, Writing to the database!\n", getName());
        // Use connection to write log to database
    }
}
....

== FileHandler

....
package org.superbiz.cdi.produces.field;

public class FileHandler implements LogHandler {

    private String name;

    public FileHandler(String name) {
        this.name = name;
    }

    @Override
    public String getName() {
        return name;
    }

    @Override
    public void writeLog(String s) {
        System.out.printf("##### Handler: %s, Writing to the file!\n", getName());
        // Escreve para o arquivo de log
    }
}
....

== LogFactory

....
package org.superbiz.cdi.produces.field;

import javax.enterprise.inject.Produces;

public class LogFactory {

    private int type = 2;

    @Produces
    LogHandler handler;

    public LogFactory(){
    	handler = getLogHandler();
    }

    public LogHandler getLogHandler() {
        switch (type) {
            case 1:
                return new FileHandler("@Produces created FileHandler!");
            case 2:
                return new DatabaseHandler("@Produces created DatabaseHandler!");
            case 3:
            default:
                return new ConsoleHandler("@Produces created ConsoleHandler!");
        }

    }
}
....

== Logger

....
package org.superbiz.cdi.produces.field;

public interface Logger {

    public void log(String s);

    public LogHandler getHandler();
}
....

== LoggerImpl

....
package org.superbiz.cdi.produces.field;

import javax.inject.Inject;
import javax.inject.Named;

@Named("logger")
public class LoggerImpl implements Logger {

    @Inject
    private LogHandler handler;

    @Override
    public void log(String s) {
        getHandler().writeLog(s);
    }

    public LogHandler getHandler() {
        return handler;
    }
}
....

== LogHandler

....
package org.superbiz.cdi.produces.field;

public interface LogHandler {

    public String getName();

    public void writeLog(String s);
}
....

== beans.xml

....
<beans xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
                            http://java.sun.com/xml/ns/javaee/beans_1_0.xsd">

</beans>
....

== LoggerTest

....
package org.superbiz.cdi.produces.field;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import javax.ejb.embeddable.EJBContainer;
import javax.inject.Inject;
import javax.naming.Context;

import static junit.framework.Assert.assertNotNull;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;

public class LoggerTest {

    @Inject
    Logger logger;

    private Context ctxt;

    @Before
    public void setUp() {
        try {
            ctxt = EJBContainer.createEJBContainer().getContext();
            ctxt.bind("inject", this);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @After
    public void cleanUp() {
        try {
            ctxt.unbind("inject");
            ctxt.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @Test
    public void testLogHandler() {
        assertNotNull(logger);
        assertFalse("Handler should not be a ConsoleHandler", logger.getHandler() instanceof ConsoleHandler);
        assertFalse("Handler should not be a FileHandler", logger.getHandler() instanceof FileHandler);
        assertTrue("Handler should be a DatabaseHandler", logger.getHandler() instanceof DatabaseHandler);
        logger.log("##### Testing write\n");
        logger = null;
    }

}
....

= Executando

....
-------------------------------------------------------
 T E S T S
-------------------------------------------------------
Running org.superbiz.cdi.produces.field.LoggerTest
INFO - ********************************************************************************
INFO - OpenEJB http://tomee.apache.org/
INFO - Startup: Thu May 10 01:28:19 CDT 2012
INFO - Copyright 1999-2012 (C) Apache OpenEJB Project, All Rights Reserved.
INFO - Version: 7.0.0-SNAPSHOT
INFO - Build date: 20120510
INFO - Build time: 04:06
INFO - ********************************************************************************
INFO - openejb.home = /home/daniel/projects/openejb/source/openejb/examples/cdi-produces-field
INFO - openejb.base = /home/daniel/projects/openejb/source/openejb/examples/cdi-produces-field
INFO - Created new singletonService org.apache.openejb.cdi.ThreadSingletonServiceImpl@a81b1fb
INFO - succeeded in installing singleton service
INFO - Using 'javax.ejb.embeddable.EJBContainer=true'
INFO - Cannot find the configuration file [conf/openejb.xml].  Will attempt to create one for the beans deployed.
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 - Creating TransactionManager(id=Default Transaction Manager)
INFO - Creating SecurityService(id=Default Security Service)
INFO - Inspecting classpath for applications: 26 urls. Consider adjusting your exclude/include.  Current settings: openejb.deployments.classpath.exclude='', openejb.deployments.classpath.include='.*'
INFO - Searched 26 classpath urls in 2015 milliseconds.  Average 77 milliseconds per url.
INFO - Beginning load: /home/daniel/projects/openejb/source/openejb/examples/cdi-produces-field/target/classes
INFO - Configuring enterprise application: /home/daniel/projects/openejb/source/openejb/examples/cdi-produces-field
INFO - Auto-deploying ejb cdi-produces-field.Comp: EjbDeployment(deployment-id=cdi-produces-field.Comp)
INFO - Configuring Service(id=Default Managed Container, type=Container, provider-id=Default Managed Container)
INFO - Auto-creating a container for bean cdi-produces-field.Comp: Container(type=MANAGED, id=Default Managed Container)
INFO - Creating Container(id=Default Managed Container)
INFO - Using directory /tmp for stateful session passivation
INFO - Enterprise application "/home/daniel/projects/openejb/source/openejb/examples/cdi-produces-field" loaded.
INFO - Assembling app: /home/daniel/projects/openejb/source/openejb/examples/cdi-produces-field
INFO - ignoreXmlConfiguration == true
INFO - ignoreXmlConfiguration == true
INFO - existing thread singleton service in SystemInstance() org.apache.openejb.cdi.ThreadSingletonServiceImpl@a81b1fb
INFO - OpenWebBeans Container is starting...
INFO - Adding OpenWebBeansPlugin : [CdiPlugin]
INFO - All injection points were validated successfully.
INFO - OpenWebBeans Container has started, it took [69] ms.
INFO - Deployed Application(path=/home/daniel/projects/openejb/source/openejb/examples/cdi-produces-field)
##### Handler: @Produces created DatabaseHandler!, Writing to the database!
INFO - Undeploying app: /home/daniel/projects/openejb/source/openejb/examples/cdi-produces-field
Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 3.79 sec

Results :

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