wicketservlet.java

Wicket一个开发Java Web应用程序框架。它使得开发web应用程序变得容易而轻松。 Wicket利用一个POJO data beans组件使得它可以与任何持久层技术相结合。

/*
 * 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.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.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * 
 * Please use {@link WicketFilter} if you require advanced chaining of resources.
 * 
 * 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>
 * 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
	 */
	public final void doGet(final HttpServletRequest servletRequest,
			final HttpServletResponse servletResponse) throws ServletException, IOException
	{
		wicketFilter.doGet(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
	 */
	public final void doPost(final HttpServletRequest servletRequest,
			final HttpServletResponse servletResponse) throws ServletException, IOException
	{
		wicketFilter.doGet(servletRequest, servletResponse);
	}

	/**
	 * Servlet initialization
	 */
	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()
			 */
			public Enumeration 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.
	 */
	public void destroy()
	{
		wicketFilter.destroy();
		wicketFilter = null;
	}

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