com.vaadin.terminal.gwt.server.SpringApplicationOSGiServlet.java Source code

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Here is the source code for com.vaadin.terminal.gwt.server.SpringApplicationOSGiServlet.java

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/*
 * Copyright 2011 Thingtrack, S.L.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
 * in compliance with the License. You may obtain a copy of the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software distributed under the License
 * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */
package com.vaadin.terminal.gwt.server;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;

import org.osgi.framework.Bundle;
import org.osgi.framework.BundleContext;
import org.osgi.framework.FrameworkUtil;
import org.osgi.framework.InvalidSyntaxException;
import org.osgi.framework.ServiceReference;
import org.osgi.framework.Version;
import org.osgi.service.packageadmin.ExportedPackage;
import org.osgi.service.packageadmin.PackageAdmin;
import org.springframework.context.ApplicationContext;

import com.vaadin.Application;

/**
 * This Servlet retrieves the Spring Application Context registered by Spring DM.
 * You have to define new init param with the name of the with the Application subclass bean.
 * @author carlos
 * 
 */
public class SpringApplicationOSGiServlet extends AbstractApplicationServlet {

    // Private fields
    private Class<? extends Application> applicationClass;

    private String applicationParam;
    private String versionParam;
    private String beanParam;

    /*
     * (non-Javadoc)
     * 
     * @see
     * com.vaadin.terminal.gwt.server.AbstractApplicationServlet#init(javax.
     * servlet.ServletConfig)
     */
    @Override
    public void init(ServletConfig servletConfig) throws ServletException {
        // TODO Auto-generated method stub
        super.init(servletConfig);

        applicationParam = servletConfig.getInitParameter("application");

        if (applicationParam == null) {
            throw new ServletException("Application not specified in servlet parameters");
        }

        versionParam = getInitParameter("version");

        if (versionParam == null) {
            throw new ServletException("Bundle Version not specified in servlet parameters");
        }

        beanParam = getInitParameter("bean");

        if (beanParam == null) {
            throw new ServletException("Bean Name not specified in servlet parameters");
        }
    }

    /*
     * (non-Javadoc)
     * 
     * @see
     * com.vaadin.terminal.gwt.server.AbstractApplicationServlet#getNewApplication
     * (javax.servlet.http.HttpServletRequest)
     */
    @Override
    protected Application getNewApplication(HttpServletRequest request) throws ServletException {

        // Creates a new application instance
        try {
            // Retrieve the Spring ApplicationContext registered as a service
            ApplicationContext springContext = getApplicationContext();

            if (!springContext.containsBean(beanParam)) {

                throw new ClassNotFoundException("No application bean found under name " + beanParam);
            }

            final Application application = (Application) springContext.getBean(beanParam);

            return application;

        } catch (ClassNotFoundException e) {
            throw new ServletException("getNewApplication failed", e);
        }
    }

    /*
     * (non-Javadoc)
     * 
     * @see
     * com.vaadin.terminal.gwt.server.AbstractApplicationServlet#getApplicationClass
     * ()
     */
    @Override
    protected Class<? extends Application> getApplicationClass() throws ClassNotFoundException {
        ApplicationContext springContext = getApplicationContext();

        if (!springContext.containsBean(beanParam)) {

            throw new ClassNotFoundException("No application bean found under name " + beanParam);
        }

        return (Class<? extends Application>) springContext.getBean(beanParam).getClass();
    }

    /**
     * @return
     * @throws ClassNotFoundException
     */
    private ApplicationContext getApplicationContext() throws ClassNotFoundException {
        BundleContext context = FrameworkUtil.getBundle(this.getClass()).getBundleContext();

        ServiceReference[] refs = null;
        try {
            refs = context.getServiceReferences(ApplicationContext.class.getName(),
                    "(org.springframework.context.service.name="
                            + getSymbolicName(this.applicationParam, this.versionParam) + ")");
        } catch (InvalidSyntaxException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }

        ApplicationContext springContext = null;
        if (refs != null && refs.length > 0) {
            springContext = (ApplicationContext) context.getService(refs[0]);
        }

        if (springContext == null) {
            throw new ClassNotFoundException("Spring ApplicationContext has not been registered");
        }
        return springContext;
    }

    @SuppressWarnings("unchecked")
    private String getSymbolicName(String className, String version) throws ClassNotFoundException {
        Version versionParam = version != null ? Version.parseVersion(version) : null;

        String packageName = className;
        String[] splittedString = packageName.split("\\.");

        if (splittedString.length > 0)
            packageName = packageName.substring(0,
                    packageName.length() - splittedString[splittedString.length - 1].length() - 1);

        BundleContext context = FrameworkUtil.getBundle(this.getClass()).getBundleContext();
        ServiceReference ref = context.getServiceReference(PackageAdmin.class.getName());
        PackageAdmin packageAdmin = (PackageAdmin) context.getService(ref);

        ExportedPackage[] packages = packageAdmin.getExportedPackages(packageName);
        if (packages == null) {
            return null;
        }
        for (ExportedPackage packageImported : packages) {
            Bundle bundle = packageImported.getExportingBundle();

            if (bundle == null) {
                return null;
            }
            if (versionParam == null || versionParam.equals(bundle.getVersion())) {

                return bundle.getSymbolicName();
            }

        }

        return null;

    }

}