org.springframework.roo.classpath.itd
Interface ItdMetadataProvider

Type Parameters:

ID - the identifier

T - the ITD metadata

All Superinterfaces:

org.springframework.roo.metadata.MetadataProvider

All Known Subinterfaces:

ItdRoleAwareMetadataProvider

All Known Implementing Classes:

AbstractItdMetadataProvider

public interface ItdMetadataProvider
extends org.springframework.roo.metadata.MetadataProvider

Indicates a MetadataService that supports ITDs.

ITD usage in ROO adopts some conventions to facilitate ease of use.

The first requirement is that metadata identification is by way of the PhysicalTypeIdentifierNamingUtils if the type that will receive any potential introduction. It is important to recognize that implementations may not actually introduce members via a traditional ITD but instead may place the methods directly in the physical type. This is a supported usage pattern and is highly compatible with using the aforementioned metadata identification approach.

The second requirement is that if an implementation wishes to create an ITD it does so strictly in accordance with the following compilation unit file placement and naming convention. The convention is that all ITD compilation units must be placed in the same source directory as the PhysicalTypeIdentifierNamingUtils used for metadata identification. Secondly, the ITD compilation unit must adopt an identical filename as that used by the PhysicalTypeIdentifierNamingUtils, except that the extension must be ".aj" and there must be a suffix immediately following the file name (but prior to the extension). The suffix is composed of "_Roo_" plus an implementation-specific string, as returned by getItdUniquenessFilenameSuffix(). For example, consider a PhysicalTypeIdentifierNamingUtils for com/foo/Bar.java within Path.SRC_MAIN_JAVA and a result of getItdUniquenessFilenameSuffix() being "Jpa". This would indicate an ITD filename within Path.SRC_MAIN_JAVA of "com/foo/Bar_Roo_Jpa.aj".

The third requirement is that implementations can assume ItdFileDeletionService will automatically eliminate any unnecessary ITDs that no longer have a PhysicalTypeIdentifierNamingUtils that could potentially receive them. Conversely, if a PhysicalTypeIdentifierNamingUtils does exist, it is required that the implementation will delete any unnecessary ITDs if the ITD should no longer exist and also monitor that ITD for changes.

A recommendation is that implementations listen to PhysicalTypeMetadataProvider so as to be notified of any new PhysicalTypeMetadata that becomes available. Implementations should consider whether the PhysicalTypeMetadata represents an instance that should have ITD-specific metadata created. If so, the implementation should create a metadata instance and cause that instance to monitor the PhysicalTypeMetadata directly. The ItdMetadataProvider should instantiate an ITD metadata instance with both the PhysicalTypeMetadata it is monitoring, plus FileMetadata for the .aj it should monitor (even if the .aj does not yet exist, because the metadata will create it).

Since:

1.0

Author:

Ben Alex

Method Summary

String	getIdForPhysicalJavaType(String physicalJavaTypeIdentifier) Obtains an identifier that would be validly recognized by this ItdMetadataProvider instance.
String	getItdUniquenessFilenameSuffix() Returns the suffix that makes filenames unique for this implementation.

Methods inherited from interface org.springframework.roo.metadata.MetadataProvider

get, getProvidesType

Method Detail

getItdUniquenessFilenameSuffix

String getItdUniquenessFilenameSuffix()

Returns the suffix that makes filenames unique for this implementation. This suffix is appended to the end of the PhysicalTypeIdentifierNamingUtils filename + "_Roo_" portion. This suffix should not contain any periods and as such does not represent the filename's extension.

Returns:

the filename suffix that makes ITDs produced by this implementation unique (cannot be null or an empty string)

getIdForPhysicalJavaType

String getIdForPhysicalJavaType(String physicalJavaTypeIdentifier)

Obtains an identifier that would be validly recognized by this ItdMetadataProvider instance. The identifier must represent the presented physical Java type identifier.

The presented physical Java type identifier need not presently exist in the MetadataService. Implementations must not rely on the metadata being available at this moment. Implementations by returning a value from this method do not guarantee that metadata for the returned identifier will subsequently made available. As such this method is a basic conversion method and shouldn't perform any analysis.

Parameters:

physicalJavaTypeIdentifier - to convert into a local metadata identifier (required)

Returns:

an identifier acceptable to this provider (must not return null or an empty string)