dominikdorn.com » JavaEE6

CDI/Weld beans.xml XSD/DTD

Dominik Dorn — Fri, 20 Aug 2010 14:21:09 +0000

As I’m often looking for the correct header of the beans.xml file required for Web Beans / Context and Dependency Injection (CDI) to work, I decided to share this simple header here with you.

If you don’t have anything to declare, create an empty beans.xml like this one



If you have to declare alternatives or interceptors, do it like this

    
        
            com.dominikdorn.dc.passwordReset.PasswordResetService
        
        com.dominikdorn.dc.passwordReset.StudyGuruPasswordReset
    


A good IDE will help you with creating a proper beans.xml as soon as you specify the xml namespace.
Popular implementations of CDI are

CanDI
Weld
OpenWebBeans

JPA2 Abstract DAO, Criteria Query & the “like” Operator

Dominik Dorn — Wed, 16 Jun 2010 13:48:17 +0000

For a project at the university, I had to implement an abstract search in an abstract JPA Dao.

Maybe this class comes handy for some of you

package com.dominikdorn.rest.dao;

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.PersistenceException;
import javax.persistence.TypedQuery;
import javax.persistence.criteria.*;
import java.lang.reflect.ParameterizedType;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;

/**
 * @author Dominik Dorn
 */
public class AbstractJpaDao {
    @PersistenceContext
    protected EntityManager em;

    protected Class entityClass;

    public Class getEntityClass() {
        return entityClass;
    }

    public void setEntityClass(Class entityClass) {
        this.entityClass = entityClass;
    }

    public AbstractJpaDao() {
        ParameterizedType genericSuperclass = (ParameterizedType) getClass().getGenericSuperclass();
        this.entityClass = (Class) genericSuperclass.getActualTypeArguments()[0];
    }

    public AbstractJpaDao(Class clazz) {
        this.entityClass = clazz;
    }

    public EntityManager getEm() {
        return em;
    }

    public AbstractJpaDao setEm(EntityManager em) {
        this.em = em;
        return this;
    }

    @Override
    public TYPE persist(TYPE item) {
        if (item == null)
            throw new PersistenceException("Item may not be null");
        em.persist(item);
        return item;
    }

    @Override
    public TYPE update(TYPE item) {
        if (item == null)
            throw new PersistenceException("Item may not be null");

        em.merge(item);
        return item;
    }

    @Override
    public List getAll() {
        CriteriaQuery cq = em.getCriteriaBuilder().createQuery();
        cq.select(cq.from(entityClass));
        return em.createQuery(cq).getResultList();
    }

    @Override
    public TYPE getById(Long id) {
        if (id == null || id < 1)
            throw new PersistenceException("Id may not be null or negative");

        return (TYPE) em.find(entityClass, id);
    }

    @Override
    public void delete(TYPE item) {
        if (item == null)
            throw new PersistenceException("Item may not be null");

        em.remove(em.merge(item));
    }

    @Override
    public List findByAttributes(Map attributes) {
        List results;
        //set up the Criteria query
        CriteriaBuilder cb = em.getCriteriaBuilder();
        CriteriaQuery cq = cb.createQuery(getEntityClass());
        Root foo = cq.from(getEntityClass());

        List predicates = new ArrayList();
        for(String s : attributes.keySet())
        {
            if(foo.get(s) != null){
                predicates.add(cb.like((Expression) foo.get(s), "%" + attributes.get(s) + "%" ));
            }
        }
        cq.where(predicates.toArray(new Predicate[]{}));
        TypedQuery q = em.createQuery(cq);

        results = q.getResultList();
        return results;
    }
}

To instantiate this for an Entity, e.g. “Item”, simply do this

  // get an entityManager somewhere here
  AbstractJpaDao dao = new AbstractJpaDao();
dao.setEm(em);

now you can use this Data Access Object for your persistence stuff.

To now search for entities in your DB, you can use the method findByAttributes which takes a map and searches for appropriate items.
If your Entity looks like this

@Entity
public class Item {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO, generator = "ITEM_GEN")
    @SequenceGenerator(name="ITEM_GEN", allocationSize=25, sequenceName = "item_seq")
    private long id;

    @Basic
    private String name;

    @Basic
    private String description;

    @Basic
    private Integer size;
// constructors, getters, setters

you could search for an item which names contain “test” like this


Map attr = new Hashmap();
attr.put("name", "test");
List results = dao.findByAttributes(attr);

which comes quite handy in my opinion. Also note, that you don’t have to pre-generate your JPA2 Model classes.

Essential Glassfish Performance Tuning Blogs

Dominik Dorn — Mon, 14 Jun 2010 14:42:53 +0000

In my time on the Glassfish users mailinglist, I came across some important links for everyone setting up a Glassfish server for production.

This is my personal bookmarks list, that may also serve its purpose to others.

Putting Glassfish v3 in Production – Essential surviving Guide: This post describes basic performance enhancements you can get with changing settings in your domain.xml configuration and adjusting jvm settings
Monitoring in Glassfish: This post shows how to further enhance the thread pool settings for your Glassfish domain and how to determine the correct settings for your system
Tomcat/Glassfish/Jetty on Port 80 with IPTables + NAT: This post describes, how you can run your Glassfish hosted webapps on Port 80 without running a Apache or other web server in front of it, thus you are able to fully utilize every aspect of Glassfishs new asynchronous architecture without always have to think of that old Indian making problems (Comet etc.)
Blog Post on Java.net: This post by user "radix_zero" also suggests a few other tricks, like creating multiple connection pools to the same data source or running multiple real-domains, each in a own JVM.
Another Post on Java.net: The thread points out that one should use distinct thread pools for each http-listener to prevent locking between the listeners

This post will be updated with new additional & helpful links, as soon as I get aware of them.

Do you have interesting links? Post them in the comments!

Maven + JUnit + ClassFormatError: Absent Code attribute in method that is not native or abstract in class file

Dominik Dorn — Tue, 11 May 2010 19:39:29 +0000

Once in a while one stumbles upon an error message like this

java.lang.ClassFormatError: Absent Code attribute in method that is not native or abstract in class file javax/mail/Session

This happens if your code compiles against incomplete classes, like the JavaEE6 Api and your Unit tests try to access code thats not there. JUnit will simply fail and mark the test as error, printing something like this

Tests in error:
  initializationError(com.dominikdorn.dc.passwordReset.SimplePasswordResetServiceTest)

and the corresponding surefire text file starts like this:

-------------------------------------------------------------------------------
Test set: com.dominikdorn.dc.passwordReset.SimplePasswordResetServiceTest
-------------------------------------------------------------------------------
Tests run: 1, Failures: 0, Errors: 1, Skipped: 0, Time elapsed: 0.022 sec <<< FAILURE!
initializationError(com.dominikdorn.dc.passwordReset.SimplePasswordResetServiceTest)  Time elapsed: 0.005 sec  <<< ERROR!
java.lang.ClassFormatError: Absent Code attribute in method that is not native or abstract in class file javax/mail/Session
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:621)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
        at java.net.URLClassLoader.access$000(URLClassLoader.java:56)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
....

The Solution
You have to compile against real-implementations of the classes. You do that by adding those dependencies before the most generic dependency in your pom.xml

As example, we add javax.mail BEFORE javaee6-api like this


...
    

        
            javax.mail
            mail
            1.4
            provided
        
        
            javax
            javaee-api
            6.0
            provided

If you are deploying your App on an Appserver like Glassfish or JBoss AS, leave the scope of javax.mail:mail as provided to prevent the inclusion of the jar in the final webapp.

I now list required dependencies for various Absent Code Errors I've encountered and still encountering. This post will be updated every time I solve another of these problems.

JavaMail: javax/mail/Session


...
    
        
            javax.mail
            mail
            1.4
            provided

Servlet 3.0


...
    
               
                       org.glassfish
                       javax.servlet
                       3.0
                       provided
               
...
    
....
    
               
               
                       Glassfish
                       Glassfish Maven2 Repository
                       http://download.java.net/maven/glassfish/

JPA2: javax/persistence/PersistenceException

...
        
            org.eclipse.persistence
            javax.persistence
            2.0.0
            provided
        
...
..

...
    
...
        
            eclipse
            Eclipse Maven Repository
            http://www.eclipse.org/downloads/download.php?r=1&nf=1&file=/rt/eclipselink/maven.repo

JAX-RS: javax/ws/rs/core/UriBuilder

        
            com.sun.jersey
            jersey-core
            1.1.5
            provided
        

        
            com.sun.jersey
            jersey-json
            1.1.5
            provided
        

        
            com.sun.jersey
            jersey-test-framework
            1.1.5.1
            test

more to come soon!

CDI/Weld manual lookup

Dominik Dorn — Wed, 21 Apr 2010 18:04:28 +0000

So, you’re ended up in a situation, where you are somewhere (e.g. a javax.faces.Converter) where you are unable to simple @Inject SomeClass ?

I had the problem, that I had a FacesConverter like this:

import javax.annotation.ManagedBean;
import javax.annotation.PostConstruct;
import javax.enterprise.context.RequestScoped;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.Converter;
import javax.faces.convert.FacesConverter;
import javax.inject.Inject;

@FacesConverter(forClass = AvailableCountry.class)
@ManagedBean // does not help 
@RequestScoped // does not help 
public class AvailableCountryConverter implements Converter
{
	@Inject
	AvailableCountryDao dao;

	@PostConstruct
	public void postConstruct()
	{
		System.out.println("calling postConstruct");
	}

	public Object getAsObject(FacesContext facesContext, UIComponent
			component, String value) {
		if (value == null || value.length() == 0) {
			return null;
		}
		return dao.find(getKey(value));
	}

	Long getKey(String value) {
		Long key;
		key = Long.valueOf(value);
		return key;
	}

	String getStringKey(long value) {
		StringBuffer sb = new StringBuffer();
		sb.append(value);
		return sb.toString();
	}

	public String getAsString(FacesContext facesContext, UIComponent
			component, Object object) {
		if (object == null) {
			return null;
		}
		if (object instanceof AvailableCountry) {
			AvailableCountry o = (AvailableCountry) object;
			return getStringKey(o.getCountry().getId());
		} else {
			throw new IllegalArgumentException("object " + object + "
					is of type " + object.getClass().getName() + "; expected type: " +
					AvailableCountry.class.getName());
		}
	}
}

But my DAO was not injected, nor was the postConstruct method triggered by CDI.

Why?
Because the bean is not managed by CDI, not even when annotating it with @ManagedBean because it gets created by the JSF-Lifecycle and not by CDI.

Well.. but how to manually lookup a Bean with CDI / Weld?

First, you need to get the BeanManager. When you have a FacesContext (like in the converter above), you can get it like this:

    public BeanManager getBeanManager()
    {
        return (BeanManager)
              ((ServletContext) facesContext.getExternalContext().getContext())
                   .getAttribute("javax.enterprise.inject.spi.BeanManager");
    }

If you don’t have access to a FacesContext, ServletContext or similar, you can lookup the BeanManager through JNDI

    public BeanManager getBeanManager()
    {
        try{
            InitialContext initialContext = new InitialContext();
            return (BeanManager) initialContext.lookup("java:comp/BeanManager");
        catch (NamingException e) {
            log.error("Couldn't get BeanManager through JNDI");
            return null;
        }
    }

After you’ve got your BeanManager, simply lookup your Bean like this:
(In my case, I wanted to lookup a bean with the type AvailableCountryDao)
Type-based CDI manual lookup

    public AvailableCountryDao getFacade()
    {
        BeanManager bm = getBeanManager();
        Bean bean = (Bean) bm.getBeans(AvailableCountryDao.class).iterator().next();
        CreationalContext ctx = bm.createCreationalContext(bean);
        AvailableCountryDao dao = (AvailableCountryDao) bm.getReference(bean, AvailableCountryDao.class, ctx); // this could be inlined, but intentionally left this way
        return dao;
    }

Thanks to my friend Lincoln Baxter, III for the snipped.

Name-based CDI manual lookup

    public Object getBeanByName(String name) // eg. name=availableCountryDao
    {
        BeanManager bm = getBeanManager();
        Bean bean = bm.getBeans(name).iterator().next();
        CreationalContext ctx = bm.createCreationalContext(bean); // could be inlined below
        Object o = bm.getReference(bean, bean.getClass(), ctx); // could be inlined with return
        return o;
    }

So, now you’re able to manually lookup beans with CDI.
In case you have the same problem (with Converters/Validators) like I had above, checkout Seam Faces, where this problem already is fixed,
meaning your @ManagedBean annotated Converter/Validator is working as expected with @Inject, @PostConstruct & @PreDestroy

File Templates for web.xml & web-fragment.xml (Servlet 2.3, 2.4, 2.5 + 3.0)

Dominik Dorn — Thu, 25 Mar 2010 12:20:55 +0000

As I sometimes need these, I have compiled a list of the valid headers of the web.xml and web-fragment.xml file for servlet version 2.3 until 3.0.
Maybe you find them as handy as I do.

web.xml v2.3

web.xml v2.4

web.xml v2.5

web.xml v3.0

web-fragment.xml:

Using complex urls & regular expressions with PrettyFaces

Dominik Dorn — Wed, 17 Mar 2010 20:15:24 +0000

If you like to construct complex & pretty urls with JSF2 & PrettyFaces, you might be interested in the following few lines of code.

In our example, we want to match a URL like this one


http://www.studyguru.eu/at/tuwien/184.153--Entwurfsmethoden-fuer-verteilte-Systeme

Previously I tried to match it with a PrettyFaces Pattern/Regex like this:

But thankfully, PrettyFaces >2.0.4 supports directly populating the RequestParams!

Configure your pretty-config like this:


....

    

        /path/to/coursePage.xhtml
    
....

and use JSF2′s viewParams like this:






    
        
    

    
        
    
    
        
    

    

coursePage

countryCode #{ coursePageBean.countryCode} 

courseId #{coursePageBean.courseId}

universityCode #{coursePageBean.universityCode}

Voila! You now can match complex urls with PrettyFaces and apply all your custom validators
to your Pretty URL

Disabling ;jsessionid url-appending Servlet 3.0

Dominik Dorn — Tue, 09 Mar 2010 16:36:30 +0000

I’ve noticed that google indexed various pages of mine with appended “;jsessionid=somehash”
Thats not only ugly, but also a security risk.

But how to disable Session Tracking by URL? How to set it to Cookie only ?

Take this!

Update: Jan Luehe showed me a way, how to do this in web.xml only – without a listener

 
    
COOKIE
URL
SSL

if you prefer to do it programmatically (e.g. when doing a custom web-app configuration wizzard or something like this), do it this way:

package com.dominikdorn.dc.listeners;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.SessionTrackingMode;
import javax.servlet.annotation.WebListener;
import java.util.HashSet;
import java.util.Set;

/**
 * This Listener sets the tracking modes used by the servletContext
 */
@WebListener(value = "This listener sets the session tracking modes")
public class SetSessionTrackingModeListener implements ServletContextListener {

    // Public constructor is required by servlet spec

    public SetSessionTrackingModeListener() {
    }

    public void contextInitialized(ServletContextEvent sce) {
        Set modes = new HashSet();
        // modes.add(SessionTrackingMode.URL); // thats the default behaviour!
        modes.add(SessionTrackingMode.COOKIE);
//        modes.add(SessionTrackingMode.SSL); // this works only with client certs.
        sce.getServletContext().setSessionTrackingModes(modes);
    }

    public void contextDestroyed(ServletContextEvent sce) {
    }

}

Questions? Comments? Post them here!

X-UA-Compatible Java Servlets / JSF

Dominik Dorn — Tue, 09 Mar 2010 16:16:41 +0000

A User on the glassfish mailing list posted a question:

I would like to aks it. How must set up ie8 compatibility mode in glassfish?
This is the iis setting:

Well… how to do that?

Simply create a Servlet Filter!

package com.dominikdorn.dc.filters;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.annotation.WebInitParam;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.logging.Logger;

@WebFilter(urlPatterns = {"/*"}, initParams = {@WebInitParam(name = "compatibilityMode", value = "IE=EmulateIE7")})
public class UserAgentCompatibleFilter implements javax.servlet.Filter {
    private Logger log = Logger.getLogger("UserAgentCompatibleFilter");
    private String compatibilityMode;

    public void destroy() {
    }

    public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain) throws ServletException, IOException {
        if (compatibilityMode != null) {
            HttpServletResponse res = (HttpServletResponse) resp;
            res.addHeader("X-UA-Compatible", compatibilityMode);
        }
        chain.doFilter(req, resp);
    }

    public void init(FilterConfig config) throws ServletException {
        compatibilityMode = config.getInitParameter("compatibilityMode");
        if (compatibilityMode == null) {
            log.warning("No CompatibilityMode set for UserAgentCompatibleFilter, thus disabling it");
        }
    }
}

If you’re not using Servlet 3.0, simply comment out the @WebServlet annotation. If you want to customize
the header, add this to your web.xml and modify it, so that it suit your needs.

    
        UserAgentCompatibleFilter
        com.dominikdorn.dc.filters.UserAgentCompatibleFilter
        
compatibilityMode
IE=EmulateIE7
        
    

    
        UserAgentCompatibleFilter
        /*

To see if it works, compile and redeploy your app.. you can then test it, e.g. with curl:

curl -D - http://localhost:8080/info.xhtml
HTTP/1.1 200 OK
X-Powered-By: Servlet/3.0
Server: GlassFish v3
Set-Cookie: JSESSIONID=3afbe6498aa3f495e8340d8e67ef; Path=/
X-UA-Compatible: IE=EmulateIE7
X-Powered-By: JSF/2.0
Content-Type: text/html;charset=UTF-8
Content-Length: 2997
Date: Tue, 09 Mar 2010 16:09:03 GMT

Suggestions? Comment here!

Really basic file upload with HTML + JSF2

Dominik Dorn — Fri, 05 Mar 2010 18:34:12 +0000

The “ironic programmer” published an article, how to create a really basic file upload with jsf2. He has not created any custom tags, but simply added a file-input field in his view and made the server populate a byte-array in his bean.

His post was influenced by Uploading files with JSF 2.0 and Servlet 3.0 by BalusC.

He probably missed our JSF2 FileUpload-Github-Project where the taglib is ready for usage and really simple to integrate.

Still, thumbs up for the nice post!