org.apache.dubbo.common.extension

Annotation Type Activate

@Documented
 @Retention(value=RUNTIME)
 @Target(value={TYPE,METHOD})
public @interface Activate

Activate. This annotation is useful for automatically activate certain extensions with the given criteria, for examples: @Activate can be used to load certain Filter extension when there are multiple implementations.

1. group() specifies group criteria. Framework SPI defines the valid group values.
2. value() specifies parameter key in URL criteria.

SPI provider can call ExtensionLoader.getActivateExtension(URL, String, String) to find out all activated extensions with the given criteria.

See Also:

SPI, URL, ExtensionLoader

Optional Element Summary

Optional Elements

Modifier and Type	Optional Element and Description
String[]	after Deprecated.
String[]	before Deprecated.
String[]	group Activate the current extension when one of the groups matches.
String[]	onClass Activate loadClass when the current extension when the specified className all match
int	order Absolute ordering info, optional Ascending order, smaller values will be in the front o the list.
String[]	value Activate the current extension when the specified keys appear in the URL's parameters.

Element Detail

group

public abstract String[] group

Activate the current extension when one of the groups matches. The group passed into ExtensionLoader.getActivateExtension(URL, String, String) will be used for matching.

Returns:

group names to match

See Also:

ExtensionLoader.getActivateExtension(URL, String, String)

Default:

{}

value

public abstract String[] value

Activate the current extension when the specified keys appear in the URL's parameters.

For example, given @Activate("cache, validation"), the current extension will be return only when there's either cache or validation key appeared in the URL's parameters.

Returns:

URL parameter keys

See Also:

ExtensionLoader.getActivateExtension(URL, String), ExtensionLoader.getActivateExtension(URL, String, String)

Default:

{}

before

@Deprecated
public abstract String[] before

Deprecated.

Relative ordering info, optional Deprecated since 2.7.0

Returns:

extension list which should be put before the current one

Default:

{}

after

@Deprecated
public abstract String[] after

Deprecated.

Relative ordering info, optional Deprecated since 2.7.0

Returns:

extension list which should be put after the current one

Default:

{}

order

public abstract int order

Absolute ordering info, optional Ascending order, smaller values will be in the front o the list.

Returns:

absolute ordering info

Default:

0

onClass

public abstract String[] onClass

Activate loadClass when the current extension when the specified className all match

Returns:

className names to all match

Default:

{}