org.directwebremoting.WebContextFactory Maven / Gradle / Ivy

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DWR is easy Ajax for Java. It makes it simple to call Java code directly from Javascript. It gets rid of almost all the boilerplate code between the web browser and your Java code. This version 4.0.2 works with Jakarta Servlet 4.0.2.

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package org.directwebremoting;

import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Accessor for the current {@link WebContext}.
 * @author Joe Walker [joe at getahead dot ltd dot uk]
 */
public class WebContextFactory
{
    /**
     * Accessor for the current {@link WebContext}.
     * @return The current WebContext or null if the current thread was not
     * started by DWR.
     */
    public static WebContext get()
    {
        if (builder == null)
        {
            return null;
        }

        return builder.get();
    }

    /**
     * The WebContextBuilder from which we will get WebContext objects
     */
    private static WebContextBuilder builder = null;

    /**
     * Internal method to allow us to get the WebContextBuilder from which we
     * will get WebContext objects.
     * Do NOT call this method from outside of DWR.
     * @param container ...
     */
    public static void attach(Container container)
    {
        WebContextFactory.builder = container.getBean(WebContextBuilder.class);
    }

    /**
     * Class to enable us to access servlet parameters.
     * This class is for internal use only.
     */
    public interface WebContextBuilder
    {
        /**
         * Accessor for the WebContext that is associated with this thread.
         * This method is only for use internally to DWR.
         * @see WebContextFactory#get()
         * @return ...
         */
        WebContext get();

        /**
         * Make the current thread know what the current request is.
         * This method is only for use internally to DWR.
         * @param container The IoC container
         * @param request The incoming http request
         * @param response The outgoing http reply
         * @see #disengageThread()
         */
        void engageThread(Container container, HttpServletRequest request, HttpServletResponse response);

        /**
         * Make the current thread know what the current request is.
         * Uses an existing WebContext for example from another thread.
         * This method is only for use internally to DWR.
         * @see #disengageThread()
         * @param webContext ...
         */
        void engageThread(WebContext webContext);

        /**
         * Unset the current ExecutionContext
         * This method is only for use internally to DWR.
         * @see #engageThread(Container, HttpServletRequest, HttpServletResponse)
         */
        void disengageThread();
    }

    /**
     * The log stream
     */
    private static final Log log = LogFactory.getLog(WebContextFactory.class);
}