Red Hat Summit Red Hat SummitSupportConsoleDéveloppeursCommencer un essaiContact

Ce contenu n'est pas disponible dans la langue sélectionnée.

6.2. Configuring components via components.xml

The components.xml file is more powerful than property settings. It lets you:
  • configure components that have been installed automatically, including built-in components, and application components that have been annotated with @Name and picked up by Seam's deployment scanner.
  • install classes with no @Name annotation as Seam components. This is most useful for infrastructural components which can be installed multiple times with different names (for example, Seam-managed persistence contexts).
  • install components that do have a @Name annotation but are not installed by default because of an @Install annotation that indicates the component should not be installed.
  • override the scope of a component.
A components.xml file appears in one of three locations:
  • The WEB-INF directory of a WAR.
  • The META-INF directory of a JAR.
  • Any JAR directory containing classes with a @Name annotation.
Seam components are installed when the deployment scanner discovers a class with a @Name annotation in an archive with a seam.properties file, or a META-INF/components.xml file, unless the component also has an @Install annotation indicating that it should not be installed by default. The components.xml file handles special cases where the annotations must be overridden.
For example, the following components.xml file installs jBPM: 
<components xmlns="http://jboss.com/products/seam/components" 
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
            xmlns:bpm="http://jboss.com/products/seam/bpm"> 
  <bpm:jbpm/> 
</components>
Copy to Clipboard Toggle word wrap
The following example also installs jBPM: 
<components> 
  <component class="org.jboss.seam.bpm.Jbpm"/> 
</components>
Copy to Clipboard Toggle word wrap
This example installs and configures two different Seam-managed persistence contexts: 
<components xmlns="http://jboss.com/products/seam/components" 
            xmlns:persistence="http://jboss.com/products/seam/persistence">

    <persistence:managed-persistence-context name="customerDatabase"
         persistence-unit-jndi-name="java:/customerEntityManagerFactory"/>
        
    <persistence:managed-persistence-context name="accountingDatabase"
       persistence-unit-jndi-name="java:/accountingEntityManagerFactory"/>            

</components>
Copy to Clipboard Toggle word wrap
This example also installs and configures two different Seam-managed persistence contexts: 
<components>
  <component name="customerDatabase" 
             class="org.jboss.seam.persistence.ManagedPersistenceContext">
    <property name="persistenceUnitJndiName">
      java:/customerEntityManagerFactory
    </property>
  </component>
    
  <component name="accountingDatabase"
             class="org.jboss.seam.persistence.ManagedPersistenceContext">
    <property name="persistenceUnitJndiName">
      java:/accountingEntityManagerFactory
    </property>
  </component>
</components>
Copy to Clipboard Toggle word wrap
The following examples create a session-scoped Seam-managed persistence context. (This is not recommended in practice.) 
<components xmlns="http://jboss.com/products/seam/components" 
            xmlns:persistence="http://jboss.com/products/seam/persistence">

  <persistence:managed-persistence-context 
          name="productDatabase" scope="session"
          persistence-unit-jndi-name="java:/productEntityManagerFactory"/>        

</components>
Copy to Clipboard Toggle word wrap 
<components>
            
  <component name="productDatabase" scope="session"
             class="org.jboss.seam.persistence.ManagedPersistenceContext">
    <property name="persistenceUnitJndiName">
      java:/productEntityManagerFactory
    </property>
  </component>

</components>
Copy to Clipboard Toggle word wrap
The auto-create option is commonly used for infrastructural objects such as persistence contexts, removing the need to specify create=true explicitly when using the @In annotation. 
<components xmlns="http://jboss.com/products/seam/components" 
            xmlns:persistence="http://jboss.com/products/seam/persistence">

  <persistence:managed-persistence-context 
          name="productDatabase" auto-create="true"
          persistence-unit-jndi-name="java:/productEntityManagerFactory"/>        

</components>
Copy to Clipboard Toggle word wrap 
<components>
            
  <component name="productDatabase"
    auto-create="true"
          class="org.jboss.seam.persistence.ManagedPersistenceContext">
    <property name="persistenceUnitJndiName">
      java:/productEntityManagerFactory
    </property>
  </component>

</components>
Copy to Clipboard Toggle word wrap
The <factory> declaration specifies a value- or method-binding expression that will initialize the value of a context variable when it is first referenced. 
<components> 
  <factory name="contact" method="#{contactManager.loadContact}" 
           scope="CONVERSATION"/>
</components>
Copy to Clipboard Toggle word wrap
You can create an alias (a second name) for a Seam component like so: 
<components> 
  <factory name="user" value="#{actor}" scope="STATELESS"/> 
</components>
Copy to Clipboard Toggle word wrap
You can even create an alias for a commonly used expression: 
<components> 
  <factory name="contact" value="#{contactManager.contact}" 
           scope="STATELESS"/>
</components>
Copy to Clipboard Toggle word wrap
auto-create="true" is often used with the <factory> declaration: 
<components> 
  <factory name="session" value="#{entityManager.delegate}" 
           scope="STATELESS" auto-create="true"/> 
</components>
Copy to Clipboard Toggle word wrap
The same components.xml file is sometimes used (with minor changes) during both deployment and testing. Seam allows wildcards of the form @wildcard@ to be placed in components.xml, which can be replaced at deployment time by either your Ant build script, or providing a file named components.properties in the classpath. (The latter approach appears in the Seam examples.)
Red Hat logoGithubredditYoutubeTwitter

Apprendre

Essayez, achetez et vendez

Communautés

À propos de la documentation Red Hat

Nous aidons les utilisateurs de Red Hat à innover et à atteindre leurs objectifs grâce à nos produits et services avec un contenu auquel ils peuvent faire confiance. Découvrez nos récentes mises à jour.

Rendre l’open source plus inclusif

Red Hat s'engage à remplacer le langage problématique dans notre code, notre documentation et nos propriétés Web. Pour plus de détails, consultez le Blog Red Hat.

À propos de Red Hat

Nous proposons des solutions renforcées qui facilitent le travail des entreprises sur plusieurs plates-formes et environnements, du centre de données central à la périphérie du réseau.

Theme

© 2026 Red HatRetour au début