The basics of Eclipse plug-in development (5) Making OSGi bundles

Reprint Source: Http://www.cnblogs.com/liuzhuo

1. Creating an OSGi Project

First open the New Project Wizard and choose Create Eclipse plug-in project. SELECT [OSGi Framework] in the [Target Platform] option.

Figure 5-1 Creating a plug-in project

Select when selecting a template, and click Done after the Hello OSGi bundle.

Figure 5-2 Selecting an OSGi template

After the project is generated, click [Launch Frame (Launch the framework)] in the manifest editor to run the newly generated OSGi Bundle. There may be a large number of errors after execution. The reason is that the osgibundle in Eclipse is registered in the OSGi framework, but the UI-related parts do not start. We go to [run Configuration], remove all bundle bindings, and select only the bundles we are currently testing. (My own project even canceled the operation also error: (~ ~)

When the framework is running, enter the start and stop instructions to the console window to see the effect.

Figure 5-4 Hello OSGi

2. OSGi Service and Tracker

In the previous section we made a simple bundle that outputs messages at startup and stop. The code is a simple implementation of the SART () and Stop () methods of the Bundleactivator interface, in which the information is typed using SYSTEM.OUT.PRINTLN.

Code 1

public class Activator implements Bundleactivator {public void start (Bundlecontext context) throws Exception {System.out. println ("Hello world!!");} public void Stop (Bundlecontext context) throws Exception {System.out.println ("Goodbye world!!");}}

The OSGi bundle works by providing a start and stop approach to lifecycle management in the OSGi framework. The OSGi framework has a service feature that can be used as a common (Common) for multiple bundles, called OSGi service.

Code 2 The simplest OSGi Service

public class Osgiservice {public void dosomething () {System.out.println ("Running Common Service");}}

Code 3 performing OSGi Service

public class Activator implements Bundleactivator {public void start (Bundlecontext context) throws Exception {System.out. println ("Hello world!!"); /Registered OSGi Servicecontext.registerservice (OSGiService.class.getName (), New Osgiservice (), New Properties ());} public void Stop (Bundlecontext context) throws Exception {System.out.println ("Goodbye world!!"); /Generate service Trackerservicetracker tracker = new Servicetracker (context,osgiservice.class.getname (), NULL); Tracker.open ();//Get Serviceosgiservice service = (osgiservice) tracker.getservice ();//Execute serviceservice.dosomething ( );}}

Let's look at the effect of the above bundle execution.

Code 4

3. Installation and update of Bundel

The OSGi framework can also install and unload bundles without restarting the JAVAVM. Below we make a new bundle,newbundle output a line of messages at start and stop.

Code 5 Newbundle

public class Activator implements Bundleactivator {public void start (Bundlecontext context) throws Exception {System.out. println ("New bundle start!!");} public void Stop (Bundlecontext context) throws Exception {System.out.println ("New bundle stop!!");}}

Export the project to the C packing directory and launch the OSGi console input install File:\\\c:\plugins\newbundle_1.0.0.201008182238.jar. Then confirm the bundle installation through the SS command.

Code 6 installation and uninstallation of bundles

Osgi> Install File:\\\c:\plugins\newbundle_1.0.0.201008182238.jarbundle ID is 321osgi> SS NewFramework is Launched.id      State       Bundle321     installed   newbundle_1.0.0.201008182238osgi> start newbundlenew Bundle start!! osgi> Uninstall Newbundlenew Bundle stop!! osgi> SS Newframework is launched.id      State       bundleosgi>

The above code shows that the Stop method is called first when the bundle is unloaded. A simple summary of the description of the bundle's manifest file is given in the following table:

Project name	Description
Manifest-version	The manifest file for the jar package specifies the version number, which is typically 1.0
Bundle-manifestversion	The bundle's manifest file specifies the version, usually 2
Bundle-name	The name of the bundle
Bundle-symbolicname	The Synbo name of the bundle, which is registered with this name in OSGi
Bundle-version	The version of the bundle. It is possible in OSGi that multiple versions of the same bundle coexist
Bundle-activator	Managing the class name of the bundle life cycle
Bundle-vendor	Defines the name of the organization that made the bundle
Bundle-activationpolicy	Specifies the policy that the bundle starts.
Import-package	Packages referenced by the bundle are specified
Export-package	The bundle is assigned to the package exposed by his bundle.
Required-bundle	Bundles referenced by the bundle are specified

The basics of Eclipse plug-in development (5) Making OSGi bundles