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 boiler plate code between the web browser and your Java code.

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/*
 * Copyright 2005 Joe Walker
 *
 * 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 org.directwebremoting;

import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Accessor for the current WebContext.
 * @author Joe Walker [joe at getahead dot ltd dot uk]
 */
public class WebContextFactory
{
    /**
     * Accessor for the current 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();
    }

    /**
     * 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 builder The factory object (from DwrServlet)
     */
    public static void setWebContextBuilder(WebContextBuilder builder)
    {
        WebContextFactory.builder = builder;
    }

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

    /**
     * Class to enable us to access servlet parameters.
     */
    public interface WebContextBuilder
    {
        /**
         * Make the current thread know what the current request is.
         * This method is only for use internally to DWR.
         * @param request The incoming http request
         * @param response The outgoing http reply
         * @param config The servlet configuration
         * @param context The servlet context
         * @param container The IoC container
         * @see #unset()
         */
        void set(HttpServletRequest request, HttpServletResponse response, ServletConfig config, ServletContext context, Container container);

        /**
         * @return The WebContext that is associated with this thread
         */
        WebContext get();

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