ServletContextFacesContextFactory.java

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package javax.faces;

import java.lang.reflect.Field;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.faces.context.FacesContext;
import javax.faces.context.FacesContextFactory;
import javax.faces.lifecycle.Lifecycle;
import javax.servlet.ServletContext;

/*
 * Bug 20458755
 
 * This class provides a utility method to look up the current FacesContext
 * without performing the additional check introduced in FacesContext.getCurrentInstance()
 * by this bug fix.

 * This class also is a FacesContextFactory implementation that ignores 
 * all arguments and is able to look up the FacesContext corresponding
 * to the ServletContext corresponding to the current Thread context ClassLoader.

 * This FacesContextFactory implementation is used by FacesContext.getCurrentInstance()
 * so that the init FacesContext can be correctly looked up regardless of 
 * thread re-use.
 */
final class ServletContextFacesContextFactory extends FacesContextFactory {
    static final String SERVLET_CONTEXT_FINDER_NAME = "com.sun.faces.ServletContextFacesContextFactory";
    static final String SERVLET_CONTEXT_FINDER_REMOVAL_NAME = "com.sun.faces.ServletContextFacesContextFactory_Removal";

    private static final Logger LOGGER;

    static {
        LOGGER = Logger.getLogger("javax.faces", "javax.faces.LogStrings");
    }

    private ThreadLocal<FacesContext> facesContextCurrentInstance;
    private ConcurrentHashMap<Thread, FacesContext> facesContextThreadInitContextMap;
    private ConcurrentHashMap<FacesContext, ServletContext> initContextServletContextMap;

    ServletContextFacesContextFactory() {
        try {
            Field instanceField = FacesContext.class.getDeclaredField("instance");
            instanceField.setAccessible(true);
            facesContextCurrentInstance = (ThreadLocal<FacesContext>) instanceField.get(null);

            Field threadInitContextMapField = FacesContext.class.getDeclaredField("threadInitContext");
            threadInitContextMapField.setAccessible(true);
            facesContextThreadInitContextMap = (ConcurrentHashMap<Thread, FacesContext>) threadInitContextMapField.get(null);

            Field initContextServletContextMapField = FacesContext.class.getDeclaredField("initContextServletContext");
            initContextServletContextMapField.setAccessible(true);
            initContextServletContextMap = (ConcurrentHashMap<FacesContext, ServletContext>) initContextServletContextMapField.get(null);

        } catch (IllegalAccessException ex) {
            if (LOGGER.isLoggable(Level.SEVERE)) {
                LOGGER.log(Level.SEVERE, "Unable to access instance field of FacesContext", ex);
            }
        } catch (IllegalArgumentException ex) {
            if (LOGGER.isLoggable(Level.SEVERE)) {
                LOGGER.log(Level.SEVERE, "Unable to access instance field of FacesContext", ex);
            }
        } catch (NoSuchFieldException ex) {
            if (LOGGER.isLoggable(Level.SEVERE)) {
                LOGGER.log(Level.SEVERE, "Unable to access instance field of FacesContext", ex);
            }
        } catch (SecurityException ex) {
            if (LOGGER.isLoggable(Level.SEVERE)) {
                LOGGER.log(Level.SEVERE, "Unable to access instance field of FacesContext", ex);
            }
        }
    }

    /*
     * This method does what FacesContext.getCurrentInstance() did *before* the fix for Bug
     * 20458755.
     */
    FacesContext getFacesContextWithoutServletContextLookup() {
        FacesContext result = facesContextCurrentInstance.get();
        if (null == result) {
            if (null != facesContextThreadInitContextMap && !facesContextThreadInitContextMap.isEmpty()) {
                result = facesContextThreadInitContextMap.get(Thread.currentThread());
            }
        }
        return result;
    }

    /*
     * Consult the initContextServletContextMap (reflectively obtained from the FacesContext in our
     * ctor). If it is non-empty, obtain the ServletContext corresponding to the current Thread's
     * context ClassLoader. If found, use the initContextServletContextMap to find the FacesContext
     * corresponding to that ServletContext.
     */

    @Override
    public FacesContext getFacesContext(Object context, Object request, Object response, Lifecycle lifecycle) throws FacesException {
        FacesContext result = null;
        if (null != initContextServletContextMap && !initContextServletContextMap.isEmpty()) {
            ServletContext servletContext = (ServletContext) FactoryFinder.FACTORIES_CACHE.getServletContextForCurrentClassLoader();
            if (null != servletContext) {
                for (Map.Entry<FacesContext, ServletContext> entry : initContextServletContextMap.entrySet()) {
                    if (servletContext.equals(entry.getValue())) {
                        result = entry.getKey();
                        break;
                    }
                }
            }
        }

        return result;
    }

}