SpringDM笔记16-处理OSGi服务的动态性:事件
1. Service registration and unregistration events
??? Spring DM provides two ways to implement and configure listeners:
??? ■ Make the service implement the OsgiServiceRegistrationListener interface. When this interface
?????? is present, Spring DM will automatically register the bean as a listener of the service’s lifecycle.
?????? This is a reasonable approach, but it ties your implementation to the Spring DM API.
??? ■ Specify a service listener configuration in the service tag. This approach is preferred because it
?????? allows you to use a POJO as a listener. The association between events and callback methods is
?????? specified through the service listener configuration.
??? Spring DM provides a registration-listener element to be used as an inner tag of the service tag.
??? Attributes of the registration-listener element：
??? (1)Attribute:ref
??? Description:Specifies the identifier of the bean to be used as a service listener.
??? (2)Attribute: registrationmethod?
??? Description:Specifies the method of the listener bean to be called when the service is registered.
??? The method must have exactly two parameters: One of the type of the? service and corresponds
??? to the service that’s being listened to. A second which corresponds to the service’s properties
??? and can be of type Map or Dictionary.
??? (3)Attribute:? unregistrationmethod?
??? Description:Specifies the method of the listener bean to be called when the service? is
??? unregistered. The method signature follows the same rules as for registration-method.
??? 示例：
??? Contents of a registration service listener：
??? public class TestRegistrationServiceListener {
???????? public void onServiceRegistered(TestService service, Map properties) {
?????????????? (...)
???????? }
???????? public void onServiceUnregistered(TestService service, Map properties) {
?????????????? (...)
???????? }
??? }
??? <bean id="testListener"?
?????????? ref="testServiceBean"
?????????? interface="com.manning.sdmia.springdm.service.TestService">
?????????? <registration-listener ref="testListener" registration-method="onServiceRegistered"
????????????????? unregistration-method="onServiceUnregistered"/>
??? </osgi:service>
2. Service bind and unbind events
??? Spring DM provides two different methods for receiving notifications when the configured service
??? is bound or unbound by Spring DM.
??? ■ Make the listener implement the OsgiServiceLifecyleListener interface. When this interface is
?????? present, Spring DM will automatically use the interface’s methods when binding and unbinding
?????? occur.
??? ■ Specify a service reference listener configuration in the reference tag. This approach is
?????? preferred because it allows you to use a POJO as a listener. The association between events
?????? and callback methods is specified through the service reference listener’s configuration.
?????? Attributes of the listener tag：
?????? (1)ref:Specifies the identifier of the bean to be used as a service listener.
?????? (2)bind-method:Specifies the method of the listener to be called when a reference to the
?????????? service is bound. The method must have two parameters: The first is of the type of the
?????????? service and corresponds to the service. The second corresponds to the service properties
?????????? and can be of type Map or Dictionary.
?????? (3)unbind-method:Specifies the method of the listener to be called when a reference to the
?????????? service is unbound. The method signature follows the same rules as for the bindmethod
?????????? attribute.
?????? 示例：
?????? public interface OsgiServiceLifecycleListener {
???????????? void bind(Object service, Map properties);
???????????? void unbind(Object service, Map properties);
?????? }
????? public class TestServiceListener {
??????????? public void onServiceBound(TestService service, Map properties) {
?????????????????? (...)
??????????? }
??????????? public void onServiceUnbound(TestService service, Map properties) {
?????????????????? (...)
??????????? }
????? }
???? <bean id="testListener"
???????????? bind-method="onServiceBound" unbind-
??????????????????? method="onServiceUnbound"/>
???? </osgi:service>
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