How to Develop Web applications under the osgi framework? This is a problem. There are two ways to run a web application under the osgi framework: the first is to use a Web container as a bundle and then run it in the osgi framework. Second, place the osgi framework in a Web container. This seriesArticleThis is based on the first running mode. At the end of the series, we will introduce the second running mode as appropriate.
Step 1: Open eclipse and create a bundle ProjectHelloworldbundle(For detailed process of creating a bundle project using elicpse, refer to osgi series-develop bundle using eclipse ). The directory structure of the helloworldbundle project is as follows:
Step 2: OpenManifest. MFFile, switchDependenciesTab, inRequired plug-insAdd two dependency plug-ins:Javax. servletAndOrg. Eclipse. osgi. Services. Javax. servlet provides the servlet API required for servlet development. org. Eclipse. osgi. Services provides the HTTP service used when activator registers the servlet.
Save manifest. MF. The complete anifest. MF content is as follows:
Manifest-version: 1.0Bundle-manifestversion:2Bundle-Name: helloworldbundlebundle-symbolicname: helloworldbundlebundle-version:1.0.0Bundle-Activator: helloworldbundle. activatorimport-package: org. osgi. Framework;Version = "1.3.0"Bundle-requiredexecutionenvironment: JavaSE-1.6Require-Bundle: javax. servlet;Bundle-version = "2.5.0 ",Org. Eclipse. osgi. Services;Bundle-version = "3.3.0"
Step 3: CreateHelloservlet. JavaAs our servlet demo. The content of helloservlet. Java is as follows:
Package Helloworldbundle; Import Java. Io. ioexception; Import Java. Io. printwriter; Import Javax. servlet. http. httpservlet; Import Javax. servlet. http. httpservletrequest; Import Javax. servlet. http. httpservletresponse; Import Javax. servlet. http. httpsession; Import Org. osgi. Framework. bundlecontext; Public Class Helloservlet Extends Httpservlet { Private Static Final Long Serialversionuid = 1l ; @ Suppresswarnings ( "UNUSED" ) Private Bundlecontext context; Public Helloservlet (bundlecontext context ){ This . Context = Context ;} Public Void Doget (httpservletrequest request, httpservletresponse response) Throws Ioexception {httpsession session = Request. getsession (); Int Counter; If ( Null ! = Session. getattribute ("counter") {Counter = (Integer) Session. getattribute ("counter") + 1 ;} Else {Counter = 1 ;} Session. setattribute ( "Counter" , Counter); response. setcharacterencoding ( "GBK" ); Response. setcontenttype ( "Text/html" ); Printwriter out = Response. getwriter (); Out. println ( "<HTML>"); Out. println ( "<Body>" ); Out. println ( "<Head>" ); Out. println ( "<Title> Hello World </title>" ); Out. println ( "</Head>" ); Out. println ( "<Body>" ); Out. println ( "Now time:" + ( New Java. util. Date () + ", counter:" + Counter); Out. println ( "</Body>" ); Out. println ( "</Html>"); Out. Flush (); Out. Close ();}}
Step 4: ImplementActivator. JavaTo manage the lifecycle of helloworldbundle. In the start and stop methods of activator, a service listener is added and deleted to listen for HTTP service registration and uninstallation. When the HTTP service is registered, helloservlet is also registered to the HTTP service. When the HTTP service is uninstalled, helloservlet is also uninstalled from the HTTP service. The content of activator. Java is as follows:
Package Helloworldbundle; Import Org. osgi. Framework. bundleactivator; Import Org. osgi. Framework. bundlecontext; Import Org. osgi. Framework. serviceevent; Import Org. osgi. Framework. servicelistener; Import Org. osgi. Framework. servicereference; Import Org. osgi. Service. http. httpservice; Public Class Activator Implements Bundleactivator, servicelistener { Private Bundlecontext CTX; Private Servicereference Ref; Public Void Start (bundlecontext context) Throws Exception {CTX = Context; context. addservicelistener ( This , "(Objectclass =" + httpservice. Class . Getname () + ")" );} Public Void Stop (bundlecontext context) Throws Exception {context. removeservicelistener ( This );} Public Void Servicechanged (serviceevent event ){ Switch (Event. GetType ()){ Case Serviceevent. Registered: registerservlet (); Break ; Case Serviceevent. unregistering: unregisterservlet (); Break ;}} Private Void Registerservlet (){ If (Ref = Null ) {Ref = CTX. getservicereference (httpservice. Class ); If (Ref! = Null ){ Try {Httpservice HTTP = CTX. getservice (REF); http. registerservlet ( "/Demo/Hello ", New Helloservlet (CTX ), Null , Null ); System. Out. println ( "/Demo/Hello already registered" );} Catch (Exception e) {e. printstacktrace ();}}}} Private Void Unregisterservlet (){ If (Ref! = Null ){ Try {Httpservice HTTP = CTX. getservice (REF); http. unregister ( "/Demo/hello" ); System. Out. println ( "/Demo/Hello has been uninstalled"); Ref = Null ;} Catch (Exception e) {e. printstacktrace ();}}}}
Step 5: Select elicpse from the menuRun> run commands..., In the pop-upRun deploymentsFind in the list on the left of the dialog boxOsgi framework, Click the new button:
In the bundles list on the right, selectWorkspaceUnderHellowordbundleProject, and thenTarget PlatformSelect a project:
ClickRunButton. If everything is normal, something we are familiar with will appear.Osgi>Prompt:
Step 6: Open your browser and enter the URLHttp: // localhost/demo/HelloIf the following picture is displayed, congratulations, you have succeeded.
For writing this article, I would like to thank osgi practices and equinox framework for web development in the osgi environment. Thank you!
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