The AnnotationDriver reads the mapping metadata from docblock annotations.
Locates the file that contains the metadata information for a given class name.
Base driver for file-based metadata drivers.
The DriverChain allows you to add multiple other mapping drivers for certain namespaces.
The PHPDriver includes php files which just populate ClassMetadataInfo instances with plain PHP code.
The StaticPHPDriver calls a static loadMetadata() method on your entity classes where you can manually populate the ClassMetadata instance.
The Symfony File Locator makes a simplifying assumptions compared to the DefaultFileLocator. By assuming paths only contain entities of a certain namespace the mapping files consists of the short classname only.