RELEASE_2_1_13/src/blocks/paranoid/java/org/apache/cocoon/servlet/BootstrapServlet.java

/*
 * 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.cocoon.servlet;

import java.io.File;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Enumeration;
import java.util.Set;

import javax.servlet.RequestDispatcher;
import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;

/**
 * A bootstrap servlet to allow Cocoon to run in servlet engines that aren't fully
 * compliant with the servlet 2.2 spec.
 * <p>
 * This servlet adds a mandatory "context-dir" parameter to those accepted by {@link CocoonServlet},
 * which should point to Cocoon's context directory (e.g. "<code>/path-to-webapp/cocoon</code>").
 * This directory is used to :
 * <ul>
 * <li>build a classloader with the correct class path with the contents of
 *     <code>WEB-INF/classes</code> and <code>WEB-INF/lib</code> (see
 *     {@link ParanoidClassLoader}),</li>
 * <li>resolve paths for context resources.
 * </ul>
 *
 * @author <a href="mailto:sylvain@apache.org">Sylvain Wallez</a>
 * @version CVS $Id$
 */

public class BootstrapServlet extends ParanoidCocoonServlet {
    
    protected File contextDir;
    
	protected File getContextDir() throws ServletException {
		
		ServletContext context = getServletContext();
		ServletConfig config = getServletConfig();
		
		log("getRealPath(\"/\") = " + context.getRealPath("/"));

		String contextDirParam = config.getInitParameter("context-directory");
		
		if (contextDirParam == null) {
				throw new ServletException("The 'context-directory' parameter must be set to the root of the servlet context");
		}
        
		// Ensure context dir doesn't end with a "/" (servlet spec says that paths for
		// getResource() should start by a "/")
		if (contextDirParam.endsWith("/")) {
			contextDirParam = contextDirParam.substring(0, contextDirParam.length() - 1);
		}
        
		// Ensure context dir exists and is a directory
		this.contextDir = new File(contextDirParam);
		if (!this.contextDir.exists()) {
			String msg = "Context dir '" + this.contextDir + "' doesn't exist";
			log(msg);
			throw new ServletException(msg);
		}

		if (!this.contextDir.isDirectory()) {
			String msg = "Context dir '" + this.contextDir + "' should be a directory";
			log(msg);
			throw new ServletException(msg);
		}
        
		context.log("Context dir set to " + this.contextDir);
		
		return this.contextDir;
	}


    protected void initServlet() throws ServletException {
        
        ServletContext newContext = new ContextWrapper(getServletContext(), this.contextDir);
        ServletConfig newConfig = new ConfigWrapper(getServletConfig(), newContext);
        
        this.servlet.init(newConfig);        
    }

    //-------------------------------------------------------------------------
    /**
     * Implementation of <code>ServletConfig</code> passed to the actual servlet.
     * It wraps the original config object and returns the new context.
     */
    public static class ConfigWrapper implements ServletConfig {
        ServletConfig config;
        ServletContext context;
        
        /**
         * Builds a <code>ServletConfig</code> using a servlet name and
         * a <code>ServletContext</code>.
         */
        public ConfigWrapper(ServletConfig config, ServletContext context) {
            this.config = config;
            this.context = context;
        }
        public String getServletName() {
            return config.getServletName();
        }
        
        public Enumeration getInitParameterNames() {
            return this.config.getInitParameterNames();
        }
        
        public ServletContext getServletContext() {
            return this.context;
        }
        
        public String getInitParameter(String name) {
            return config.getInitParameter(name);
        }
    }

    //-------------------------------------------------------------------------
    /**
     * Wrapper for the <code>ServletContext</code> passed to the actual servlet.
     * It implements all resource-related methods using the provided context
     * root directory. Other calls are delegated to the wrapped context.
     */
    public static class ContextWrapper implements ServletContext {
        ServletContext context;
        File contextRoot;
        
        /**
         * Builds a wrapper around an existing context, and handle all
         * resource resolution relatively to <code>contextRoot</code>
         */
        public ContextWrapper(ServletContext context, File contextRoot) {
            this.context = context;
            this.contextRoot = contextRoot;
        }
        
        public ServletContext getContext(String param) {
            return this.context.getContext(param);
        }
    
        public int getMajorVersion() {
            return this.context.getMajorVersion();
        }
    
        public int getMinorVersion() {
            return this.context.getMinorVersion();
        }
    
        public String getMimeType(String param) {
            return this.context.getMimeType(param);
        }

        /**
         * Returns the resource URL by appending <code>path</code> to the context
         * root. If this doesn't point to an existing file, <code>null</code> is
         * returned.
         */
        public URL getResource(String path) throws MalformedURLException {
            File file = new File(this.contextRoot, path);
            if (file.exists()) {
                URL result = file.toURL();
                //this.context.log("getResource(" + path + ") = " + result);
                return result;
            } else {
                //this.context.log("getResource(" + path + ") = null");
                return null;
            }
        }
    
        /**
         * Returns the stream for the result of <code>getResource()</code>, or
         * <code>null</code> if the resource doesn't exist.
         */
        public InputStream getResourceAsStream(String path) {
            try {
                URL url = getResource(path);
                return (url == null) ? null : url.openStream();
            } catch(Exception e) {
                this.context.log("getResourceAsStream(" + path + ") failed", e);
                return null;
            }
        }
    
        public RequestDispatcher getRequestDispatcher(String param) {
            return this.context.getRequestDispatcher(param);
        }
    
        public RequestDispatcher getNamedDispatcher(String param) {
            return this.context.getNamedDispatcher(param);
        }

        /**
         * @deprecated The method BootstrapServlet.ContextWrapper.getServlet(String)
         *             overrides a deprecated method from ServletContext.
         * @see <a href="http://java.sun.com/j2ee/sdk_1.3/techdocs/api/javax/servlet/ServletContext.html#getServlet(java.lang.String)">ServletContext#getServlet(java.lang.String)</a>
         */
        public Servlet getServlet(String param) throws ServletException {
            return this.context.getServlet(param);
        }

        /**
         * @deprecated The method BootstrapServlet.ContextWrapper.getServlets()
         *             overrides a deprecated method from ServletContext.
         * @see <a href="http://java.sun.com/j2ee/sdk_1.3/techdocs/api/javax/servlet/ServletContext.html#getServlets()">ServletContext#getServlets()</a>
         */
        public Enumeration getServlets() {
            return this.context.getServlets();
        }

        /**
         * @deprecated The method BootstrapServlet.ContextWrapper.getServletNames()
         *             overrides a deprecated method from ServletContext.
         * @see <a href="http://java.sun.com/j2ee/sdk_1.3/techdocs/api/javax/servlet/ServletContext.html#getServletNames()">ServletContext#getServletNames()</a>
         */
        public Enumeration getServletNames() {
            return this.context.getServletNames();
        }
    
        public void log(String msg) {
            this.context.log(msg);
        }

        /** @deprecated use {@link #log(String message, Throwable throwable)} instead. */
        public void log(Exception ex, String msg) {
            this.context.log(ex, msg);
        }
    
        public void log(String msg, Throwable thr) {
            this.context.log(msg, thr);
        }

        /**
         * Appends <code>path</code> to the context root.
         */
        public String getRealPath(String path) {
            String result = this.contextRoot + path;
            //this.context.log("getRealPath(" + path + ") = " + result);
            return result;
        }
    
        public String getServerInfo() {
            return this.context.getServerInfo();
        }
    
        public String getInitParameter(String param) {
            return this.context.getInitParameter(param);
        }
    
        public Enumeration getInitParameterNames() {
            return this.context.getInitParameterNames();
        }
    
        public Object getAttribute(String param) {
            Object result = this.context.getAttribute(param);
            //this.context.log("getAttribute(" + param + ") = " + result);
            return result;
        }
    
        public Enumeration getAttributeNames() {
            return this.context.getAttributeNames();
        }
    
        public void setAttribute(String name, Object value) {
            this.context.setAttribute(name, value);
        }
    
        public void removeAttribute(String name) {
            this.context.removeAttribute(name);
        }
        
        // Implementation of Servlet 2.3 methods. This is not absolutely required
        // for real usage since this servlet is targeted at 2.2, but is needed
        // for successful compilation
        public Set getResourcePaths(String param) {
            return null;
        }
        
        public String getServletContextName() {
            return "Cocoon context";
        }
    }
}