Use OSGI Enroute Base Provider in the Java Library to implement modular development
Use OSGI Enroute Base Provider in the Java Library to implement modular development
OSGI (Open Service Gateway Initiative) is a modular system of Java, which allows developers to split the application into a series of small, reusable modules.Enroute is an OSGI -based development framework. It provides a series of basic components and tools that allow developers to build and manage modular Java applications more simply.
In the ENROUTE framework, Base Provider is a core component that provides basic functions and services for other modules and services.Base Provider contains some common functions, such as configuration management, log records, database access, etc., so that developers can easily use these functions in their modules.
To use OSGI Enroute Base Provider to implement modular development, we can follow the steps below:
1. First, we need to introduce enroute's Maven dependencies in the construction file of the project.You can add the following code fragments to the pom.xml file:
<!-- Enroute base provider -->
<dependency>
<groupId>org.apache.felix</groupId>
<artifactId>org.apache.felix.scr.annotations</artifactId>
<version>1.12.0</version>
</dependency>
<dependency>
<groupId>osgi.enroute.base.api</groupId>
<artifactId>osgi.enroute.base.api</artifactId>
<version>3.0.0</version>
</dependency>
<dependency>
<groupId>osgi.enroute.base.provider</groupId>
<artifactId>osgi.enroute.base.provider</artifactId>
<version>3.0.0</version>
</dependency>
2. Next, we need to create an OSGI component to use the Base Provider function.You can use the `@component` annotation provided by Enroute to define a component class, as shown below:
import org.osgi.service.component.annotations.Activate;
import org.osgi.service.component.annotations.Component;
import org.osgi.service.component.annotations.Reference;
import org.osgi.service.log.LogService;
@Component
public class MyComponent {
@Reference
private LogService logService;
@Activate
protected void activate() {
logService.log(LogService.LOG_INFO, "Hello from MyComponent!");
}
}
In the above code, we used the@Component` annotation to declare the `mycomponent` class as an OSGI component.Through `@Reference` Note, we injected the` logservice` into the `LogService` field.In the `Activate` method, we print a log with` logservice`.
3. Finally, we need to create an OSGI startup class to start our modular application.Create a `main` class and add the following code:
import org.apache.felix.framework.Felix;
import org.osgi.framework.Bundle;
import org.osgi.framework.BundleContext;
import org.osgi.framework.Constants;
import org.osgi.framework.launch.Framework;
import org.osgi.service.component.ComponentContext;
public class Main {
public static void main(String[] args) throws Exception {
Framework framework = new Felix(null);
framework.start();
BundleContext bundleContext = framework.getBundleContext();
Bundle baseProviderBundle = bundleContext.installBundle("base-provider.jar");
baseProviderBundle.start();
ComponentContext componentContext = bundleContext.getCurrentComponent();
MyComponent myComponent = componentContext.newInstance(MyComponent.class);
myComponent.activate();
}
}
In the above code, we use Apache Felix as the implementation of the OSGI framework.First, we created a framework instance and started it.Then, we installed the JAR package of Base Provider and started it.Finally, we used Base Provider's `ComponentContext` to instantly instantiated the` Mycomponent` class, and called the `activate` method.
Through the above steps, we successfully used the OSGI Enroute Base Provider in the Java class library to achieve a simple modular application.In actual development, we can use other functions and components of the Enroute framework to build complex modular Java applications.
