Use Apache Felix Ipojo Annotations framework to implement the method of cutting -oriented programming in the Java library
Use Apache Felix Ipojo Annotations framework to implement the method of cutting -oriented programming in the Java library
Facing -oriented programming (AOP) is a methodology for software programming. It is separated from the main business logic by focusing on cross -sectional attention points (such as log records, transaction management, and security, etc., realizing a modular and easy -to -maintain code codestructure.In Java development, facing surface programming can be achieved by using Apache Felix iPojo Annotations framework.This article will introduce how to use this framework to achieve AOP.
Apache Felix iPojo Annotations is a framework for developing OSGI components. It provides a simplified way to define and manage components, and support the use of labeling methods for injection and dependency management.We can use this framework to achieve cut -oriented programming.
First, we need to set up Maven to build a script to introduce the dependent items that are required.Add the following dependencies to the pom.xml file:
<dependencies>
<dependency>
<groupId>org.apache.felix</groupId>
<artifactId>org.apache.felix.ipojo</artifactId>
<version>1.12.1</version>
</dependency>
<!-Add other dependencies to the dependencies->
</dependencies>
Next, we can create a cut -off class to define our horizontal sectaries.The cutting type needs to be annotated using @model and @Service annotations to allow the iPOJO framework to identify it as a component and provide service functions.In addition, we can use @Bind and @UnBind annotations to annotate the way we are interested in to perform corresponding business logic when dependent changes.The following is a sample of cutting type:
import org.apache.felix.ipojo.annotations.*;
@Component
@Instantiate
@Provides
@Aspect(singleton = false)
public class LoggingAspect {
@Inject
private MyLogger logger;
@Bind
public void bindLogger(MyLogger logger) {
this.logger = logger;
}
@Unbind
public void unbindLogger(MyLogger logger) {
this.logger = null;
}
@Bind(aggregate = true, optional = true)
private void bindDependency(ServiceReference<?> reference) {
// The business logic executed when the dependence changes
}
@Unbind
private void unbindDependency(ServiceReference<?> reference) {
// The business logic executed when the dependence changes
}
@Modify
private void modifiedDependency(ServiceReference<?> reference) {
// The business logic executed when the dependence changes
}
// Other business methods
}
The LoggingAspect class in the above example is a cut -off class. It tells the IPOJO framework through the @Aspect annotation.Through @inject annotations, we injected the Mylogger class into the cut -off class.@Bind and @UnBind annotations are used to specify methods to be executed when dependent changes.Here, we can also use @Bind annotations of Aggregate and Optional properties to define the aggregation and options of dependencies.@Modify annotations are used to execute when dependent changes.
Finally, we need to create a Bundle Activator class to start and stop cutting components.The Bundle Activator class implements the BundleActivator interface, and creates an instance of cutting components in the Start method to stop the cutting component in the Stop method.The following is an example of a Bundle Activator class:
import org.osgi.framework.BundleActivator;
import org.osgi.framework.BundleContext;
import org.apache.felix.ipojo.manipulator.Manipulator;
import org.apache.felix.ipojo.manipulator.util.Strings;
public class Activator implements BundleActivator {
@Override
public void start(BundleContext context) throws Exception {
Manipulator manipulator = new Manipulator();
manipulator.manipulate(context.getBundle());
String[] components = manipulator.getComponents();
Strings.checkNotEmpty(components, "No component to instantiate");
for (String component : components) {
context.registerService(component, null, null);
}
}
@Override
public void stop(BundleContext context) throws Exception {
// Stop the cutting component
}
}
The Activator class in the above example implements the BundleActivator interface, and uses the Manipulator class in the Start method to manipulate the bundle and register the section component service.In the Stop method, we can stop the cutting components.
The above is the method of using Apache Felix Ipojo Annotations framework to implement surface -oriented programming in the Java library.By defining the cutting surface, setting up Maven to build a script and creating the Bundle Activator class, we can easily use AOP to achieve separation and modularization of cross -sectional attention points.This method can improve the maintenance of the code and reused, making the development process more simplified and effective.
