home | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Tomcat example source code file (DefaultServlet.java)

This example Tomcat source code file (DefaultServlet.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Tomcat tags/keywords

content-range, http, httpservletresponse, inputstream, inputstream, io, ioexception, ioexception, naming, namingexception, printwriter, range, range, request, resource, response, servlet, servletexception, string, string

The Tomcat DefaultServlet.java source code

/*
 * 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.catalina.servlets;


import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.RandomAccessFile;
import java.io.Reader;
import java.io.StringReader;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.StringTokenizer;

import javax.naming.InitialContext;
import javax.naming.NameClassPair;
import javax.naming.NamingEnumeration;
import javax.naming.NamingException;
import javax.naming.directory.DirContext;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.UnavailableException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;

import org.apache.catalina.Globals;
import org.apache.catalina.util.RequestUtil;
import org.apache.catalina.util.ServerInfo;
import org.apache.catalina.util.StringManager;
import org.apache.catalina.util.URLEncoder;
import org.apache.naming.resources.CacheEntry;
import org.apache.naming.resources.ProxyDirContext;
import org.apache.naming.resources.Resource;
import org.apache.naming.resources.ResourceAttributes;


/**
 * The default resource-serving servlet for most web applications,
 * used to serve static resources such as HTML pages and images.
 *
 * @author Craig R. McClanahan
 * @author Remy Maucherat
 * @version $Revision: 543680 $ $Date: 2007-06-02 02:42:36 +0200 (sam., 02 juin 2007) $
 */

public class DefaultServlet
    extends HttpServlet {


    // ----------------------------------------------------- Instance Variables


    /**
     * The debugging detail level for this servlet.
     */
    protected int debug = 0;


    /**
     * The input buffer size to use when serving resources.
     */
    protected int input = 2048;


    /**
     * Should we generate directory listings?
     */
    protected boolean listings = false;


    /**
     * Read only flag. By default, it's set to true.
     */
    protected boolean readOnly = true;


    /**
     * The output buffer size to use when serving resources.
     */
    protected int output = 2048;


    /**
     * Array containing the safe characters set.
     */
    protected static URLEncoder urlEncoder;


    /**
     * Allow customized directory listing per directory.
     */
    protected String  localXsltFile = null;


    /**
     * Allow customized directory listing per instance.
     */
    protected String  globalXsltFile = null;


    /**
     * Allow a readme file to be included.
     */
    protected String readmeFile = null;


    /**
     * Proxy directory context.
     */
    protected ProxyDirContext resources = null;


    /**
     * File encoding to be used when reading static files. If none is specified
     * the platform default is used.
     */
    protected String fileEncoding = null;
    
    
    /**
     * Minimum size for sendfile usage in bytes.
     */
    protected int sendfileSize = 48 * 1024;
    
    
    /**
     * Full range marker.
     */
    protected static ArrayList FULL = new ArrayList();
    
    
    // ----------------------------------------------------- Static Initializer


    /**
     * GMT timezone - all HTTP dates are on GMT
     */
    static {
        urlEncoder = new URLEncoder();
        urlEncoder.addSafeCharacter('-');
        urlEncoder.addSafeCharacter('_');
        urlEncoder.addSafeCharacter('.');
        urlEncoder.addSafeCharacter('*');
        urlEncoder.addSafeCharacter('/');
    }


    /**
     * MIME multipart separation string
     */
    protected static final String mimeSeparation = "CATALINA_MIME_BOUNDARY";


    /**
     * JNDI resources name.
     */
    protected static final String RESOURCES_JNDI_NAME = "java:/comp/Resources";


    /**
     * The string manager for this package.
     */
    protected static StringManager sm =
        StringManager.getManager(Constants.Package);


    /**
     * Size of file transfer buffer in bytes.
     */
    protected static final int BUFFER_SIZE = 4096;


    // --------------------------------------------------------- Public Methods


    /**
     * Finalize this servlet.
     */
    public void destroy() {
    }


    /**
     * Initialize this servlet.
     */
    public void init() throws ServletException {

        if (getServletConfig().getInitParameter("debug") != null)
            debug = Integer.parseInt(getServletConfig().getInitParameter("debug"));

        if (getServletConfig().getInitParameter("input") != null)
            input = Integer.parseInt(getServletConfig().getInitParameter("input"));

        if (getServletConfig().getInitParameter("output") != null)
            output = Integer.parseInt(getServletConfig().getInitParameter("output"));

        listings = Boolean.parseBoolean(getServletConfig().getInitParameter("listings"));

        if (getServletConfig().getInitParameter("readonly") != null)
            readOnly = Boolean.parseBoolean(getServletConfig().getInitParameter("readonly"));

        if (getServletConfig().getInitParameter("sendfileSize") != null)
            sendfileSize = 
                Integer.parseInt(getServletConfig().getInitParameter("sendfileSize")) * 1024;

        fileEncoding = getServletConfig().getInitParameter("fileEncoding");

        globalXsltFile = getServletConfig().getInitParameter("globalXsltFile");
        localXsltFile = getServletConfig().getInitParameter("localXsltFile");
        readmeFile = getServletConfig().getInitParameter("readmeFile");

        // Sanity check on the specified buffer sizes
        if (input < 256)
            input = 256;
        if (output < 256)
            output = 256;

        if (debug > 0) {
            log("DefaultServlet.init:  input buffer size=" + input +
                ", output buffer size=" + output);
        }

        // Load the proxy dir context.
        resources = (ProxyDirContext) getServletContext()
            .getAttribute(Globals.RESOURCES_ATTR);
        if (resources == null) {
            try {
                resources =
                    (ProxyDirContext) new InitialContext()
                    .lookup(RESOURCES_JNDI_NAME);
            } catch (NamingException e) {
                // Failed
                throw new ServletException("No resources", e);
            }
        }

        if (resources == null) {
            throw new UnavailableException("No resources");
        }

    }


    // ------------------------------------------------------ Protected Methods


    /**
     * Return the relative path associated with this servlet.
     *
     * @param request The servlet request we are processing
     */
    protected String getRelativePath(HttpServletRequest request) {

        // Are we being processed by a RequestDispatcher.include()?
        if (request.getAttribute(Globals.INCLUDE_REQUEST_URI_ATTR) != null) {
            String result = (String) request.getAttribute(
                                            Globals.INCLUDE_PATH_INFO_ATTR);
            if (result == null)
                result = (String) request.getAttribute(
                                            Globals.INCLUDE_SERVLET_PATH_ATTR);
            if ((result == null) || (result.equals("")))
                result = "/";
            return (result);
        }

        // No, extract the desired path directly from the request
        String result = request.getPathInfo();
        if (result == null) {
            result = request.getServletPath();
        }
        if ((result == null) || (result.equals(""))) {
            result = "/";
        }
        return (result);

    }


    /**
     * Process a GET request for the specified resource.
     *
     * @param request The servlet request we are processing
     * @param response The servlet response we are creating
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet-specified error occurs
     */
    protected void doGet(HttpServletRequest request,
                         HttpServletResponse response)
        throws IOException, ServletException {

        // Serve the requested resource, including the data content
        serveResource(request, response, true);

    }


    /**
     * Process a HEAD request for the specified resource.
     *
     * @param request The servlet request we are processing
     * @param response The servlet response we are creating
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet-specified error occurs
     */
    protected void doHead(HttpServletRequest request,
                          HttpServletResponse response)
        throws IOException, ServletException {

        // Serve the requested resource, without the data content
        serveResource(request, response, false);

    }


    /**
     * Process a POST request for the specified resource.
     *
     * @param request The servlet request we are processing
     * @param response The servlet response we are creating
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet-specified error occurs
     */
    protected void doPost(HttpServletRequest request,
                          HttpServletResponse response)
        throws IOException, ServletException {
        doGet(request, response);
    }


    /**
     * Process a POST request for the specified resource.
     *
     * @param req The servlet request we are processing
     * @param resp The servlet response we are creating
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet-specified error occurs
     */
    protected void doPut(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, IOException {

        if (readOnly) {
            resp.sendError(HttpServletResponse.SC_FORBIDDEN);
            return;
        }

        String path = getRelativePath(req);

        boolean exists = true;
        try {
            resources.lookup(path);
        } catch (NamingException e) {
            exists = false;
        }

        boolean result = true;

        // Temp. content file used to support partial PUT
        File contentFile = null;

        Range range = parseContentRange(req, resp);

        InputStream resourceInputStream = null;

        // Append data specified in ranges to existing content for this
        // resource - create a temp. file on the local filesystem to
        // perform this operation
        // Assume just one range is specified for now
        if (range != null) {
            contentFile = executePartialPut(req, range, path);
            resourceInputStream = new FileInputStream(contentFile);
        } else {
            resourceInputStream = req.getInputStream();
        }

        try {
            Resource newResource = new Resource(resourceInputStream);
            // FIXME: Add attributes
            if (exists) {
                resources.rebind(path, newResource);
            } else {
                resources.bind(path, newResource);
            }
        } catch(NamingException e) {
            result = false;
        }

        if (result) {
            if (exists) {
                resp.setStatus(HttpServletResponse.SC_NO_CONTENT);
            } else {
                resp.setStatus(HttpServletResponse.SC_CREATED);
            }
        } else {
            resp.sendError(HttpServletResponse.SC_CONFLICT);
        }

    }


    /**
     * Handle a partial PUT.  New content specified in request is appended to
     * existing content in oldRevisionContent (if present). This code does
     * not support simultaneous partial updates to the same resource.
     */
    protected File executePartialPut(HttpServletRequest req, Range range,
                                     String path)
        throws IOException {

        // Append data specified in ranges to existing content for this
        // resource - create a temp. file on the local filesystem to
        // perform this operation
        File tempDir = (File) getServletContext().getAttribute
            ("javax.servlet.context.tempdir");
        // Convert all '/' characters to '.' in resourcePath
        String convertedResourcePath = path.replace('/', '.');
        File contentFile = new File(tempDir, convertedResourcePath);
        if (contentFile.createNewFile()) {
            // Clean up contentFile when Tomcat is terminated
            contentFile.deleteOnExit();
        }

        RandomAccessFile randAccessContentFile =
            new RandomAccessFile(contentFile, "rw");

        Resource oldResource = null;
        try {
            Object obj = resources.lookup(path);
            if (obj instanceof Resource)
                oldResource = (Resource) obj;
        } catch (NamingException e) {
            ;
        }

        // Copy data in oldRevisionContent to contentFile
        if (oldResource != null) {
            BufferedInputStream bufOldRevStream =
                new BufferedInputStream(oldResource.streamContent(),
                                        BUFFER_SIZE);

            int numBytesRead;
            byte[] copyBuffer = new byte[BUFFER_SIZE];
            while ((numBytesRead = bufOldRevStream.read(copyBuffer)) != -1) {
                randAccessContentFile.write(copyBuffer, 0, numBytesRead);
            }

            bufOldRevStream.close();
        }

        randAccessContentFile.setLength(range.length);

        // Append data in request input stream to contentFile
        randAccessContentFile.seek(range.start);
        int numBytesRead;
        byte[] transferBuffer = new byte[BUFFER_SIZE];
        BufferedInputStream requestBufInStream =
            new BufferedInputStream(req.getInputStream(), BUFFER_SIZE);
        while ((numBytesRead = requestBufInStream.read(transferBuffer)) != -1) {
            randAccessContentFile.write(transferBuffer, 0, numBytesRead);
        }
        randAccessContentFile.close();
        requestBufInStream.close();

        return contentFile;

    }


    /**
     * Process a POST request for the specified resource.
     *
     * @param req The servlet request we are processing
     * @param resp The servlet response we are creating
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet-specified error occurs
     */
    protected void doDelete(HttpServletRequest req, HttpServletResponse resp)
        throws ServletException, IOException {

        if (readOnly) {
            resp.sendError(HttpServletResponse.SC_FORBIDDEN);
            return;
        }

        String path = getRelativePath(req);

        boolean exists = true;
        try {
            resources.lookup(path);
        } catch (NamingException e) {
            exists = false;
        }

        if (exists) {
            boolean result = true;
            try {
                resources.unbind(path);
            } catch (NamingException e) {
                result = false;
            }
            if (result) {
                resp.setStatus(HttpServletResponse.SC_NO_CONTENT);
            } else {
                resp.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED);
            }
        } else {
            resp.sendError(HttpServletResponse.SC_NOT_FOUND);
        }

    }


    /**
     * Check if the conditions specified in the optional If headers are
     * satisfied.
     *
     * @param request The servlet request we are processing
     * @param response The servlet response we are creating
     * @param resourceAttributes The resource information
     * @return boolean true if the resource meets all the specified conditions,
     * and false if any of the conditions is not satisfied, in which case
     * request processing is stopped
     */
    protected boolean checkIfHeaders(HttpServletRequest request,
                                     HttpServletResponse response,
                                     ResourceAttributes resourceAttributes)
        throws IOException {

        return checkIfMatch(request, response, resourceAttributes)
            && checkIfModifiedSince(request, response, resourceAttributes)
            && checkIfNoneMatch(request, response, resourceAttributes)
            && checkIfUnmodifiedSince(request, response, resourceAttributes);

    }


    /**
     * Get the ETag associated with a file.
     *
     * @param resourceAttributes The resource information
     */
    protected String getETag(ResourceAttributes resourceAttributes) {
        String result = null;
        if ((result = resourceAttributes.getETag(true)) != null) {
            return result;
        } else if ((result = resourceAttributes.getETag()) != null) {
            return result;
        } else {
            return "W/\"" + resourceAttributes.getContentLength() + "-"
                + resourceAttributes.getLastModified() + "\"";
        }
    }


    /**
     * URL rewriter.
     *
     * @param path Path which has to be rewiten
     */
    protected String rewriteUrl(String path) {
        return urlEncoder.encode( path );
    }


    /**
     * Display the size of a file.
     */
    protected void displaySize(StringBuffer buf, int filesize) {

        int leftside = filesize / 1024;
        int rightside = (filesize % 1024) / 103;  // makes 1 digit
        // To avoid 0.0 for non-zero file, we bump to 0.1
        if (leftside == 0 && rightside == 0 && filesize != 0)
            rightside = 1;
        buf.append(leftside).append(".").append(rightside);
        buf.append(" KB");

    }


    /**
     * Serve the specified resource, optionally including the data content.
     *
     * @param request The servlet request we are processing
     * @param response The servlet response we are creating
     * @param content Should the content be included?
     *
     * @exception IOException if an input/output error occurs
     * @exception ServletException if a servlet-specified error occurs
     */
    protected void serveResource(HttpServletRequest request,
                                 HttpServletResponse response,
                                 boolean content)
        throws IOException, ServletException {

        // Identify the requested resource path
        String path = getRelativePath(request);
        if (debug > 0) {
            if (content)
                log("DefaultServlet.serveResource:  Serving resource '" +
                    path + "' headers and data");
            else
                log("DefaultServlet.serveResource:  Serving resource '" +
                    path + "' headers only");
        }

        CacheEntry cacheEntry = resources.lookupCache(path);

        if (!cacheEntry.exists) {
            // Check if we're included so we can return the appropriate 
            // missing resource name in the error
            String requestUri = (String) request.getAttribute(
                                            Globals.INCLUDE_REQUEST_URI_ATTR);
            if (requestUri == null) {
                requestUri = request.getRequestURI();
            } else {
                // We're included, and the response.sendError() below is going
                // to be ignored by the resource that is including us.
                // Therefore, the only way we can let the including resource
                // know is by including warning message in response
                response.getWriter().write(
                    sm.getString("defaultServlet.missingResource",
                    requestUri));
            }

            response.sendError(HttpServletResponse.SC_NOT_FOUND,
                               requestUri);
            return;
        }

        // If the resource is not a collection, and the resource path
        // ends with "/" or "\", return NOT FOUND
        if (cacheEntry.context == null) {
            if (path.endsWith("/") || (path.endsWith("\\"))) {
                // Check if we're included so we can return the appropriate 
                // missing resource name in the error
                String requestUri = (String) request.getAttribute(
                                            Globals.INCLUDE_REQUEST_URI_ATTR);
                if (requestUri == null) {
                    requestUri = request.getRequestURI();
                }
                response.sendError(HttpServletResponse.SC_NOT_FOUND,
                                   requestUri);
                return;
            }
        }

        // Check if the conditions specified in the optional If headers are
        // satisfied.
        if (cacheEntry.context == null) {

            // Checking If headers
            boolean included =
                (request.getAttribute(Globals.INCLUDE_CONTEXT_PATH_ATTR) != null);
            if (!included
                && !checkIfHeaders(request, response, cacheEntry.attributes)) {
                return;
            }

        }

        // Find content type.
        String contentType = cacheEntry.attributes.getMimeType();
        if (contentType == null) {
            contentType = getServletContext().getMimeType(cacheEntry.name);
            cacheEntry.attributes.setMimeType(contentType);
        }

        ArrayList ranges = null;
        long contentLength = -1L;

        if (cacheEntry.context != null) {

            // Skip directory listings if we have been configured to
            // suppress them
            if (!listings) {
                response.sendError(HttpServletResponse.SC_NOT_FOUND,
                                   request.getRequestURI());
                return;
            }
            contentType = "text/html;charset=UTF-8";

        } else {

            // Parse range specifier

            ranges = parseRange(request, response, cacheEntry.attributes);

            // ETag header
            response.setHeader("ETag", getETag(cacheEntry.attributes));

            // Last-Modified header
            response.setHeader("Last-Modified",
                    cacheEntry.attributes.getLastModifiedHttp());

            // Get content length
            contentLength = cacheEntry.attributes.getContentLength();
            // Special case for zero length files, which would cause a
            // (silent) ISE when setting the output buffer size
            if (contentLength == 0L) {
                content = false;
            }

        }

        ServletOutputStream ostream = null;
        PrintWriter writer = null;

        if (content) {

            // Trying to retrieve the servlet output stream

            try {
                ostream = response.getOutputStream();
            } catch (IllegalStateException e) {
                // If it fails, we try to get a Writer instead if we're
                // trying to serve a text file
                if ( (contentType == null)
                        || (contentType.startsWith("text"))
                        || (contentType.endsWith("xml")) ) {
                    writer = response.getWriter();
                } else {
                    throw e;
                }
            }

        }

        if ( (cacheEntry.context != null) 
                || ( ((ranges == null) || (ranges.isEmpty()))
                        && (request.getHeader("Range") == null) )
                || (ranges == FULL) ) {

            // Set the appropriate output headers
            if (contentType != null) {
                if (debug > 0)
                    log("DefaultServlet.serveFile:  contentType='" +
                        contentType + "'");
                response.setContentType(contentType);
            }
            if ((cacheEntry.resource != null) && (contentLength >= 0)) {
                if (debug > 0)
                    log("DefaultServlet.serveFile:  contentLength=" +
                        contentLength);
                if (contentLength < Integer.MAX_VALUE) {
                    response.setContentLength((int) contentLength);
                } else {
                    // Set the content-length as String to be able to use a long
                    response.setHeader("content-length", "" + contentLength);
                }
            }

            InputStream renderResult = null;
            if (cacheEntry.context != null) {

                if (content) {
                    // Serve the directory browser
                    renderResult =
                        render(request.getContextPath(), cacheEntry);
                }

            }

            // Copy the input stream to our output stream (if requested)
            if (content) {
                try {
                    response.setBufferSize(output);
                } catch (IllegalStateException e) {
                    // Silent catch
                }
                if (ostream != null) {
                    if (!checkSendfile(request, response, cacheEntry, contentLength, null))
                        copy(cacheEntry, renderResult, ostream);
                } else {
                    copy(cacheEntry, renderResult, writer);
                }
            }

        } else {

            if ((ranges == null) || (ranges.isEmpty()))
                return;

            // Partial content response.

            response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT);

            if (ranges.size() == 1) {

                Range range = (Range) ranges.get(0);
                response.addHeader("Content-Range", "bytes "
                                   + range.start
                                   + "-" + range.end + "/"
                                   + range.length);
                long length = range.end - range.start + 1;
                if (length < Integer.MAX_VALUE) {
                    response.setContentLength((int) length);
                } else {
                    // Set the content-length as String to be able to use a long
                    response.setHeader("content-length", "" + length);
                }

                if (contentType != null) {
                    if (debug > 0)
                        log("DefaultServlet.serveFile:  contentType='" +
                            contentType + "'");
                    response.setContentType(contentType);
                }

                if (content) {
                    try {
                        response.setBufferSize(output);
                    } catch (IllegalStateException e) {
                        // Silent catch
                    }
                    if (ostream != null) {
                        if (!checkSendfile(request, response, cacheEntry, range.end - range.start + 1, range))
                            copy(cacheEntry, ostream, range);
                    } else {
                        copy(cacheEntry, writer, range);
                    }
                }

            } else {

                response.setContentType("multipart/byteranges; boundary="
                                        + mimeSeparation);

                if (content) {
                    try {
                        response.setBufferSize(output);
                    } catch (IllegalStateException e) {
                        // Silent catch
                    }
                    if (ostream != null) {
                        copy(cacheEntry, ostream, ranges.iterator(),
                             contentType);
                    } else {
                        copy(cacheEntry, writer, ranges.iterator(),
                             contentType);
                    }
                }

            }

        }

    }


    /**
     * Parse the content-range header.
     *
     * @param request The servlet request we are processing
     * @param response The servlet response we are creating
     * @return Range
     */
    protected Range parseContentRange(HttpServletRequest request,
                                      HttpServletResponse response)
        throws IOException {

        // Retrieving the content-range header (if any is specified
        String rangeHeader = request.getHeader("Content-Range");

        if (rangeHeader == null)
            return null;

        // bytes is the only range unit supported
        if (!rangeHeader.startsWith("bytes")) {
            response.sendError(HttpServletResponse.SC_BAD_REQUEST);
            return null;
        }

        rangeHeader = rangeHeader.substring(6).trim();

        int dashPos = rangeHeader.indexOf('-');
        int slashPos = rangeHeader.indexOf('/');

        if (dashPos == -1) {
            response.sendError(HttpServletResponse.SC_BAD_REQUEST);
            return null;
        }

        if (slashPos == -1) {
            response.sendError(HttpServletResponse.SC_BAD_REQUEST);
            return null;
        }

        Range range = new Range();

        try {
            range.start = Long.parseLong(rangeHeader.substring(0, dashPos));
            range.end =
                Long.parseLong(rangeHeader.substring(dashPos + 1, slashPos));
            range.length = Long.parseLong
                (rangeHeader.substring(slashPos + 1, rangeHeader.length()));
        } catch (NumberFormatException e) {
            response.sendError(HttpServletResponse.SC_BAD_REQUEST);
            return null;
        }

        if (!range.validate()) {
            response.sendError(HttpServletResponse.SC_BAD_REQUEST);
            return null;
        }

        return range;

    }


    /**
     * Parse the range header.
     *
     * @param request The servlet request we are processing
     * @param response The servlet response we are creating
     * @return Vector of ranges
     */
    protected ArrayList parseRange(HttpServletRequest request,
                                HttpServletResponse response,
                                ResourceAttributes resourceAttributes)
        throws IOException {

        // Checking If-Range
        String headerValue = request.getHeader("If-Range");

        if (headerValue != null) {

            long headerValueTime = (-1L);
            try {
                headerValueTime = request.getDateHeader("If-Range");
            } catch (IllegalArgumentException e) {
                ;
            }

            String eTag = getETag(resourceAttributes);
            long lastModified = resourceAttributes.getLastModified();

            if (headerValueTime == (-1L)) {

                // If the ETag the client gave does not match the entity
                // etag, then the entire entity is returned.
                if (!eTag.equals(headerValue.trim()))
                    return FULL;

            } else {

                // If the timestamp of the entity the client got is older than
                // the last modification date of the entity, the entire entity
                // is returned.
                if (lastModified > (headerValueTime + 1000))
                    return FULL;

            }

        }

        long fileLength = resourceAttributes.getContentLength();

        if (fileLength == 0)
            return null;

        // Retrieving the range header (if any is specified
        String rangeHeader = request.getHeader("Range");

        if (rangeHeader == null)
            return null;
        // bytes is the only range unit supported (and I don't see the point
        // of adding new ones).
        if (!rangeHeader.startsWith("bytes")) {
            response.addHeader("Content-Range", "bytes */" + fileLength);
            response.sendError
                (HttpServletResponse.SC_REQUESTED_RANGE_NOT_SATISFIABLE);
            return null;
        }

        rangeHeader = rangeHeader.substring(6);

        // Vector which will contain all the ranges which are successfully
        // parsed.
        ArrayList<Range> result = new ArrayList();
        StringTokenizer commaTokenizer = new StringTokenizer(rangeHeader, ",");

        // Parsing the range list
        while (commaTokenizer.hasMoreTokens()) {
            String rangeDefinition = commaTokenizer.nextToken().trim();

            Range currentRange = new Range();
            currentRange.length = fileLength;

            int dashPos = rangeDefinition.indexOf('-');

            if (dashPos == -1) {
                response.addHeader("Content-Range", "bytes */" + fileLength);
                response.sendError
                    (HttpServletResponse.SC_REQUESTED_RANGE_NOT_SATISFIABLE);
                return null;
            }

            if (dashPos == 0) {

                try {
                    long offset = Long.parseLong(rangeDefinition);
                    currentRange.start = fileLength + offset;
                    currentRange.end = fileLength - 1;
                } catch (NumberFormatException e) {
                    response.addHeader("Content-Range",
                                       "bytes */" + fileLength);
                    response.sendError
                        (HttpServletResponse
                         .SC_REQUESTED_RANGE_NOT_SATISFIABLE);
                    return null;
                }

            } else {

                try {
                    currentRange.start = Long.parseLong
                        (rangeDefinition.substring(0, dashPos));
                    if (dashPos < rangeDefinition.length() - 1)
                        currentRange.end = Long.parseLong
                            (rangeDefinition.substring
                             (dashPos + 1, rangeDefinition.length()));
                    else
                        currentRange.end = fileLength - 1;
                } catch (NumberFormatException e) {
                    response.addHeader("Content-Range",
                                       "bytes */" + fileLength);
                    response.sendError
                        (HttpServletResponse
                         .SC_REQUESTED_RANGE_NOT_SATISFIABLE);
                    return null;
                }

            }

            if (!currentRange.validate()) {
                response.addHeader("Content-Range", "bytes */" + fileLength);
                response.sendError
                    (HttpServletResponse.SC_REQUESTED_RANGE_NOT_SATISFIABLE);
                return null;
            }

            result.add(currentRange);
        }

        return result;
    }



    /**
     *  Decide which way to render. HTML or XML.
     */
    protected InputStream render(String contextPath, CacheEntry cacheEntry)
        throws IOException, ServletException {

        InputStream xsltInputStream =
            findXsltInputStream(cacheEntry.context);

        if (xsltInputStream==null) {
            return renderHtml(contextPath, cacheEntry);
        } else {
            return renderXml(contextPath, cacheEntry, xsltInputStream);
        }

    }

    /**
     * Return an InputStream to an HTML representation of the contents
     * of this directory.
     *
     * @param contextPath Context path to which our internal paths are
     *  relative
     */
    protected InputStream renderXml(String contextPath,
                                    CacheEntry cacheEntry,
                                    InputStream xsltInputStream)
        throws IOException, ServletException {

        StringBuffer sb = new StringBuffer();

        sb.append("<?xml version=\"1.0\"?>");
        sb.append("<listing ");
        sb.append(" contextPath='");
        sb.append(contextPath);
        sb.append("'");
        sb.append(" directory='");
        sb.append(cacheEntry.name);
        sb.append("' ");
        sb.append(" hasParent='").append(!cacheEntry.name.equals("/"));
        sb.append("'>");

        sb.append("<entries>");

        try {

            // Render the directory entries within this directory
            NamingEnumeration enumeration = resources.list(cacheEntry.name);
            
            // rewriteUrl(contextPath) is expensive. cache result for later reuse
            String rewrittenContextPath =  rewriteUrl(contextPath);

            while (enumeration.hasMoreElements()) {

                NameClassPair ncPair = (NameClassPair) enumeration.nextElement();
                String resourceName = ncPair.getName();
                String trimmed = resourceName/*.substring(trim)*/;
                if (trimmed.equalsIgnoreCase("WEB-INF") ||
                    trimmed.equalsIgnoreCase("META-INF") ||
                    trimmed.equalsIgnoreCase(localXsltFile))
                    continue;

                CacheEntry childCacheEntry =
                    resources.lookupCache(cacheEntry.name + resourceName);
                if (!childCacheEntry.exists) {
                    continue;
                }

                sb.append("<entry");
                sb.append(" type='")
                  .append((childCacheEntry.context != null)?"dir":"file")
                  .append("'");
                sb.append(" urlPath='")
                  .append(rewrittenContextPath)
                  .append(rewriteUrl(cacheEntry.name + resourceName))
                  .append((childCacheEntry.context != null)?"/":"")
                  .append("'");
                if (childCacheEntry.resource != null) {
                    sb.append(" size='")
                      .append(renderSize(childCacheEntry.attributes.getContentLength()))
                      .append("'");
                }
                sb.append(" date='")
                  .append(childCacheEntry.attributes.getLastModifiedHttp())
                  .append("'");

                sb.append(">");
                sb.append(RequestUtil.filter(trimmed));
                if (childCacheEntry.context != null)
                    sb.append("/");
                sb.append("</entry>");

            }

        } catch (NamingException e) {
            // Something went wrong
            throw new ServletException("Error accessing resource", e);
        }

        sb.append("</entries>");

        String readme = getReadme(cacheEntry.context);

        if (readme!=null) {
            sb.append("<readme>");
        }


        sb.append("</listing>");


        try {
            TransformerFactory tFactory = TransformerFactory.newInstance();
            Source xmlSource = new StreamSource(new StringReader(sb.toString()));
            Source xslSource = new StreamSource(xsltInputStream);
            Transformer transformer = tFactory.newTransformer(xslSource);

            ByteArrayOutputStream stream = new ByteArrayOutputStream();
            OutputStreamWriter osWriter = new OutputStreamWriter(stream, "UTF8");
            StreamResult out = new StreamResult(osWriter);
            transformer.transform(xmlSource, out);
            osWriter.flush();
            return (new ByteArrayInputStream(stream.toByteArray()));
        } catch (TransformerException e) {
            throw new ServletException("XSL transformer error", e);
        }
    }

    /**
     * Return an InputStream to an HTML representation of the contents
     * of this directory.
     *
     * @param contextPath Context path to which our internal paths are
     *  relative
     */
    protected InputStream renderHtml(String contextPath, CacheEntry cacheEntry)
        throws IOException, ServletException {

        String name = cacheEntry.name;

        // Number of characters to trim from the beginnings of filenames
        int trim = name.length();
        if (!name.endsWith("/"))
            trim += 1;
        if (name.equals("/"))
            trim = 1;

        // Prepare a writer to a buffered area
        ByteArrayOutputStream stream = new ByteArrayOutputStream();
        OutputStreamWriter osWriter = new OutputStreamWriter(stream, "UTF8");
        PrintWriter writer = new PrintWriter(osWriter);

        StringBuffer sb = new StringBuffer();
        
        // rewriteUrl(contextPath) is expensive. cache result for later reuse
        String rewrittenContextPath =  rewriteUrl(contextPath);

        // Render the page header
        sb.append("<html>\r\n");
        sb.append("<head>\r\n");
        sb.append("<title>");
        sb.append(sm.getString("directory.title", name));
        sb.append("</title>\r\n");
        sb.append("<STYLE>