com.alibaba.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 Relative ordering info, optional
String[]	before Relative ordering info, optional
String[]	group Activate the current extension when one of the groups matches.
int	order Absolute ordering info, optional
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

public abstract String[] before

Relative ordering info, optional

Returns:

extension list which should be put before the current one

Default:

{}

after

public abstract String[] after

Relative ordering info, optional

Returns:

extension list which should be put after the current one

Default:

{}

order

public abstract int order

Absolute ordering info, optional

Returns:

absolute ordering info

Default:

0