public final Class FactoryFinder

FactoryFinder implements the standard discovery algorithm for all factory objects specified in the JavaServer Faces APIs. For a given factory class name, a corresponding implementation class is searched for based on the following algorithm. Items are listed in order of decreasing search precedence:

• If the JavaServer Faces configuration file bundled into the WEB-INF directory of the webapp contains a factory entry of the given factory class name, that factory is used.

• If the JavaServer Faces configuration files named by the javax.faces.CONFIG_FILES ServletContext init parameter contain any factory entries of the given factory class name, those injectionProvider are used, with the last one taking precedence.

• If there are any JavaServer Faces configuration files bundled into the META-INF directory of any jars on the ServletContext's resource paths, the factory entries of the given factory class name in those files are used, with the last one taking precedence.

• If a META-INF/services/{factory-class-name} resource is visible to the web application class loader for the calling application (typically as a injectionProvider of being present in the manifest of a JAR file), its first line is read and assumed to be the name of the factory implementation class to use.

• If none of the above steps yield a match, the JavaServer Faces implementation specific class is used.

If any of the injectionProvider found on any of the steps above happen to have a one-argument constructor, with argument the type being the abstract factory class, that constructor is invoked, and the previous match is passed to the constructor. For example, say the container vendor provided an implementation of javax.faces.context.FacesContextFactory, and identified it in META-INF/services/javax.faces.context.FacesContextFactory in a jar on the webapp ClassLoader. Also say this implementation provided by the container vendor had a one argument constructor that took a FacesContextFactory instance. The FactoryFinder system would call that one-argument constructor, passing the implementation of FacesContextFactory provided by the JavaServer Faces implementation.

If a Factory implementation does not provide a proper one-argument constructor, it must provide a zero-arguments constructor in order to be successfully instantiated.

Once the name of the factory implementation class is located, the web application class loader for the calling application is requested to load this class, and a corresponding instance of the class will be created. A side effect of this rule is that each web application will receive its own instance of each factory class, whether the JavaServer Faces implementation is included within the web application or is made visible through the container's facilities for shared libraries.