WicketServlet.java :  » J2EE » wicket-1.4 » org » apache » wicket » protocol » http » Java Open Source

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.wicket.protocol.http;

import java.io.IOException;
import java.io.InputStream;
import java.util.Enumeration;

import javax.servlet.FilterConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.wicket.protocol.http.servlet.ServletWebRequest;
import org.apache.wicket.util.io.Streams;
import org.apache.wicket.util.string.Strings;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * 
 * Please use {@link WicketFilter} if you require advanced chaining of resources.
 * 
 * <p>
 * Servlet class for all wicket applications. The specific application class to instantiate should
 * be specified to the application server via an init-params argument named "applicationClassName"
 * in the servlet declaration, which is typically in a <i>web.xml </i> file. The servlet declaration
 * may vary from one application server to another, but should look something like this:
 * 
 * <pre>
 * &lt;servlet&gt;
 *   &lt;servlet-name&gt;MyApplication&lt;/servlet-name&gt;
 *   &lt;servlet-class&gt;org.apache.wicket.protocol.http.WicketServlet&lt;/servlet-class&gt;
 *   &lt;init-param&gt;
 *     &lt;param-name&gt;applicationClassName&lt;/param-name&gt;
 *     &lt;param-value&gt;com.whoever.MyApplication&lt;/param-value&gt;
 *   &lt;/init-param&gt;
 *   &lt;load-on-startup&gt;1&lt;/load-on-startup&gt;
 * &lt;/servlet&gt;
 * </pre>
 * 
 * Note that the applicationClassName parameter you specify must be the fully qualified name of a
 * class that extends WebApplication. If your class cannot be found, does not extend WebApplication
 * or cannot be instantiated, a runtime exception of type WicketRuntimeException will be thrown.
 * </p>
 * As an alternative, you can configure an application factory instead. This looks like:
 * 
 * <pre>
 * &lt;init-param&gt;
 *   &lt;param-name&gt;applicationFactoryClassName&lt;/param-name&gt;
 *   &lt;param-value&gt;teachscape.platform.web.wicket.SpringApplicationFactory&lt;/param-value&gt;
 * &lt;/init-param&gt;
 * </pre>
 * 
 * and it has to satisfy interface {@link org.apache.wicket.protocol.http.IWebApplicationFactory}.
 * 
 * <p>
 * The servlet can also be configured to skip certain paths, this is especially useful when the
 * servlet is mapped to <code>/*</code> mapping:
 * 
 * <pre>
 * &lt;init-param&gt;
 *   &lt;param-name&gt;ignorePaths&lt;/param-name&gt;
 *   &lt;param-value&gt;/images/products/,/documents/pdf/&lt;/param-value&gt;
 * &lt;/init-param&gt;
 * </pre>
 * 
 * <p>
 * When GET/POST requests are made via HTTP, a WebRequestCycle object is created from the request,
 * response and session objects (after wrapping them in the appropriate wicket wrappers). The
 * RequestCycle's render() method is then called to produce a response to the HTTP request.
 * <p>
 * If you want to use servlet specific configuration, e.g. using init parameters from the
 * {@link javax.servlet.ServletConfig}object, you should override the init() method of
 * {@link javax.servlet.GenericServlet}. For example:
 * 
 * <pre>
 * public void init() throws ServletException
 * {
 *     ServletConfig config = getServletConfig();
 *     String webXMLParameter = config.getInitParameter(&quot;myWebXMLParameter&quot;);
 *     ...
 * </pre>
 * 
 * </p>
 * In order to support frameworks like Spring, the class is non-final and the variable
 * webApplication is protected instead of private. Thus subclasses may provide their own means of
 * providing the application object.
 * 
 * @see org.apache.wicket.RequestCycle
 * @author Jonathan Locke
 * @author Timur Mehrvarz
 * @author Juergen Donnerstag
 * @author Igor Vaynberg (ivaynberg)
 * @author Al Maw
 */
public class WicketServlet extends HttpServlet
{
  private static final long serialVersionUID = 1L;

  /** Log. */
  private static final Logger log = LoggerFactory.getLogger(WicketServlet.class);

  /** The WicketFilter where all the handling is done */
  protected WicketFilter wicketFilter;

  /**
   * Handles servlet page requests.
   * 
   * @param servletRequest
   *            Servlet request object
   * @param servletResponse
   *            Servlet response object
   * @throws ServletException
   *             Thrown if something goes wrong during request handling
   * @throws IOException
   */
  @Override
  public final void doGet(final HttpServletRequest servletRequest,
    final HttpServletResponse servletResponse) throws ServletException, IOException
  {
    if (wicketFilter.doGet(servletRequest, servletResponse) == false)
    {
      fallback(servletRequest, servletResponse);
    }
  }

  /**
   * Calls doGet with arguments.
   * 
   * @param servletRequest
   *            Servlet request object
   * @param servletResponse
   *            Servlet response object
   * @see WicketServlet#doGet(HttpServletRequest, HttpServletResponse)
   * @throws ServletException
   *             Thrown if something goes wrong during request handling
   * @throws IOException
   */
  @Override
  public final void doPost(final HttpServletRequest servletRequest,
    final HttpServletResponse servletResponse) throws ServletException, IOException
  {
    if (wicketFilter.doGet(servletRequest, servletResponse) == false)
    {
      fallback(servletRequest, servletResponse);
    }
  }

  private void fallback(HttpServletRequest request, HttpServletResponse response)
    throws IOException
  {
    // The ServletWebRequest is created here to avoid code duplication. The getURL call doesn't
    // depend on anything wicket specific
    ServletWebRequest req = new ServletWebRequest(request);
    String url = req.getURL();

    // WICKET-2185: strip of query string
    if (url.indexOf('?') != -1)
    {
      url = Strings.beforeFirst(url, '?');
    }

    // Get the relative URL we need for loading the resource from the servlet context
    // NOTE: we NEED to put the '/' in front as otherwise some versions of application servers
    // (e.g. Jetty 5.1.x) will fail for requests like '/mysubdir/myfile.css'
    if ((url.length() > 0 && url.charAt(0) != '/') || url.length() == 0)
    {
      url = '/' + url;
    }

    InputStream stream = getServletContext().getResourceAsStream(url);
    String mimeType = getServletContext().getMimeType(url);

    if (stream == null)
    {
      response.sendError(HttpServletResponse.SC_NOT_FOUND);
    }
    else
    {
      if (mimeType != null)
      {
        response.setContentType(mimeType);
      }
      try
      {
        Streams.copy(stream, response.getOutputStream());
      }
      finally
      {
        stream.close();
      }
    }
  }

  /**
   * Servlet initialization
   */
  @Override
  public void init() throws ServletException
  {
    wicketFilter = newWicketFilter();
    wicketFilter.init(new FilterConfig()
    {
      /**
       * @see javax.servlet.FilterConfig#getServletContext()
       */
      public ServletContext getServletContext()
      {
        return WicketServlet.this.getServletContext();
      }

      /**
       * @see javax.servlet.FilterConfig#getInitParameterNames()
       */
      @SuppressWarnings("unchecked")
      public Enumeration<String> getInitParameterNames()
      {
        return WicketServlet.this.getInitParameterNames();
      }

      /**
       * @see javax.servlet.FilterConfig#getInitParameter(java.lang.String)
       */
      public String getInitParameter(String name)
      {
        if (WicketFilter.FILTER_MAPPING_PARAM.equals(name))
        {
          return WicketFilter.SERVLET_PATH_HOLDER;
        }
        return WicketServlet.this.getInitParameter(name);
      }

      /**
       * @see javax.servlet.FilterConfig#getFilterName()
       */
      public String getFilterName()
      {
        return WicketServlet.this.getServletName();
      }
    });
  }

  /**
   * @return The wicket filter
   */
  protected WicketFilter newWicketFilter()
  {
    return new WicketFilter();
  }

  /**
   * Servlet cleanup.
   */
  @Override
  public void destroy()
  {
    wicketFilter.destroy();
    wicketFilter = null;
  }

  /**
   * @see javax.servlet.http.HttpServlet#getLastModified(javax.servlet.http.HttpServletRequest)
   */
  @Override
  protected long getLastModified(final HttpServletRequest servletRequest)
  {
    return wicketFilter.getLastModified(servletRequest);
  }
}