org.directwebremoting.impl.DefaultWebContext 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.impl;

import java.io.IOException;
import java.io.StringWriter;

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

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.directwebremoting.Container;
import org.directwebremoting.ScriptSession;
import org.directwebremoting.WebContext;
import org.directwebremoting.extend.EnginePrivate;
import org.directwebremoting.extend.RealScriptSession;
import org.directwebremoting.extend.RealWebContext;
import org.directwebremoting.extend.ScriptSessionManager;
import org.directwebremoting.util.IdGenerator;
import org.directwebremoting.util.SwallowingHttpServletResponse;

/**
 * A default implementation of WebContext.
 * @author Joe Walker [joe at getahead dot ltd dot uk]
 */
public class DefaultWebContext extends DefaultServerContext implements RealWebContext
{
    /**
     * Create a new DefaultWebContext
     * @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 org.directwebremoting.WebContextFactory.WebContextBuilder#set(HttpServletRequest, HttpServletResponse, ServletConfig, ServletContext, Container)
     */
    public DefaultWebContext(HttpServletRequest request, HttpServletResponse response, ServletConfig config, ServletContext context, Container container)
    {
        super(config, context, container);

        this.request = request;
        this.response = response;

        Object value = container.getBean("avoidConnectionLimitWithWindowName");
        if (value != null)
        {
            avoidConnectionLimitWithWindowName = Boolean.parseBoolean(value.toString());
        }
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.extend.RealWebContext#checkPageInformation(java.lang.String, java.lang.String, java.lang.String)
     */
    public void checkPageInformation(String sentPage, String sentScriptId, String windowName)
    {
        ScriptSessionManager scriptSessionManager = getScriptSessionManager();

        // Get the httpSessionId if it exists, but don't create one if it doesn't
        String httpSessionId = null;
        HttpSession httpSession = request.getSession(false);
        if (httpSession != null)
        {
            httpSessionId = httpSession.getId();
        }

        // Check validity to the script session id. It could be invalid due to
        // to a server re-start, a timeout, a back-button, just because the user
        // is new to this page, or because someone is hacking
        RealScriptSession scriptSession = scriptSessionManager.getScriptSession(sentScriptId, sentPage, httpSessionId);
        if (scriptSession == null)
        {
            // Force creation of a new script session
            scriptSession = scriptSessionManager.createScriptSession(sentPage, httpSessionId);
            String newSessionId = scriptSession.getId();

            // Inject a (new) script session id into the page
            EnginePrivate.remoteHandleNewScriptSession(scriptSession, newSessionId);

            // Use the new script session id not the one passed in
            log.debug("ScriptSession re-sync: " + sentScriptId + " has become " + newSessionId);
            this.scriptSessionId = newSessionId;
            this.page = sentPage;
        }
        else
        {
            // This could be called from a poll or an rpc call, so this is a
            // good place to update the session access time
            scriptSession.updateLastAccessedTime();

            String storedPage = scriptSession.getPage();
            if (!storedPage.equals(sentPage))
            {
                log.error("Invalid Page: Passed page=" + sentPage + ", but page in script session=" + storedPage);
                throw new SecurityException("Invalid Page");
            }

            // The passed script session id passed the test, use it
            this.scriptSessionId = sentScriptId;
            this.page = sentPage;
        }

        if (avoidConnectionLimitWithWindowName)
        {
            if (windowName == null || windowName.equals(""))
            {
                windowName = "DWR-" + generator.generateId(16);
                EnginePrivate.remoteHandleNewWindowName(scriptSession, windowName);
            }
            scriptSession.setWindowName(windowName);
        }
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.WebContext#getCurrentPage()
     */
    public String getCurrentPage()
    {
        return page;
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.WebContext#getScriptSession()
     */
    public ScriptSession getScriptSession()
    {
        ScriptSessionManager manager = getScriptSessionManager();

        RealScriptSession scriptSession = manager.getScriptSession(scriptSessionId, null, null);
        if (scriptSession == null)
        {
            throw new SecurityException("Expected script session to exist");
        }

        return scriptSession;
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.WebContext#getSession()
     */
    public HttpSession getSession()
    {
        return request.getSession();
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.WebContext#getSession(boolean)
     */
    public HttpSession getSession(boolean create)
    {
        return request.getSession(create);
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.WebContext#getHttpServletRequest()
     */
    public HttpServletRequest getHttpServletRequest()
    {
        return request;
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.WebContext#getHttpServletResponse()
     */
    public HttpServletResponse getHttpServletResponse()
    {
        return response;
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.WebContext#forwardToString(java.lang.String)
     */
    public String forwardToString(String url) throws ServletException, IOException
    {
        StringWriter sout = new StringWriter();
        StringBuffer buffer = sout.getBuffer();

        HttpServletResponse realResponse = getHttpServletResponse();
        HttpServletResponse fakeResponse = new SwallowingHttpServletResponse(realResponse, sout, realResponse.getCharacterEncoding());

        HttpServletRequest realRequest = getHttpServletRequest();
        realRequest.setAttribute(WebContext.ATTRIBUTE_DWR, Boolean.TRUE);

        getServletContext().getRequestDispatcher(url).forward(realRequest, fakeResponse);

        return buffer.toString();
    }

    /**
     * We can turn connection limit avoidance off
     */
    private boolean avoidConnectionLimitWithWindowName = true;

    /**
     * If a window does not have a name, we give it one so we can avoid the
     * 2 connection limit
     */
    private static IdGenerator generator = new IdGenerator();

    /**
     * The unique ID (like a session ID) assigned to the current page
     */
    private String scriptSessionId = null;

    /**
     * The URL of the current page
     */
    private String page = null;

    /**
     * The HttpServletRequest associated with the current request
     */
    private HttpServletRequest request = null;

    /**
     * The HttpServletResponse associated with the current request
     */
    private HttpServletResponse response = null;

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