org.impalaframework.web.servlet.ResourceServlet.java Source code

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/*
 * Copyright 2004-2008 the original author or authors.
 *
 * 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.impalaframework.web.servlet;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.Arrays;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.zip.GZIPOutputStream;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.util.AntPathMatcher;
import org.springframework.util.ClassUtils;
import org.springframework.util.PathMatcher;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.HttpServletBean;

/**
 * Special resource servlet for efficiently resolving and rendering static resources from within a JAR file.
 * Based on original source code from Spring Web Flow js module. No other changes have been applied to the file at time of initial checkin.
 * 
 * @author Jeremy Grelle
 * @author Scott Andrews
 * @author Phil Zoio
 */
public class ResourceServlet extends HttpServletBean {

    private static final long serialVersionUID = 1L;

    private static final String HTTP_CONTENT_LENGTH_HEADER = "Content-Length";

    private static final String HTTP_LAST_MODIFIED_HEADER = "Last-Modified";

    private static final String HTTP_EXPIRES_HEADER = "Expires";

    private static final String HTTP_CACHE_CONTROL_HEADER = "Cache-Control";

    private static final Log log = LogFactory.getLog(ResourceServlet.class);

    private final String protectedPath = "/?WEB-INF/.*";

    private String jarPathPrefix = "META-INF";

    private boolean gzipEnabled = true;

    private Set<String> allowedResourcePaths = new HashSet<String>();
    {
        allowedResourcePaths.add("/**/*.css");
        allowedResourcePaths.add("/**/*.gif");
        allowedResourcePaths.add("/**/*.ico");
        allowedResourcePaths.add("/**/*.jpeg");
        allowedResourcePaths.add("/**/*.jpg");
        allowedResourcePaths.add("/**/*.js");
        allowedResourcePaths.add("/**/*.png");
        allowedResourcePaths.add("META-INF/**/*.css");
        allowedResourcePaths.add("META-INF/**/*.gif");
        allowedResourcePaths.add("META-INF/**/*.ico");
        allowedResourcePaths.add("META-INF/**/*.jpeg");
        allowedResourcePaths.add("META-INF/**/*.jpg");
        allowedResourcePaths.add("META-INF/**/*.js");
        allowedResourcePaths.add("META-INF/**/*.png");
    };

    private Map<String, String> defaultMimeTypes = new HashMap<String, String>();
    {
        defaultMimeTypes.put(".css", "text/css");
        defaultMimeTypes.put(".gif", "image/gif");
        defaultMimeTypes.put(".ico", "image/vnd.microsoft.icon");
        defaultMimeTypes.put(".jpeg", "image/jpeg");
        defaultMimeTypes.put(".jpg", "image/jpeg");
        defaultMimeTypes.put(".js", "text/javascript");
        defaultMimeTypes.put(".png", "image/png");
    }

    private Set<String> compressedMimeTypes = new HashSet<String>();
    {
        compressedMimeTypes.add("text/*");
    }

    private int cacheTimeout = 31556926;

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        String rawResourcePath = rawResourcePath(request);

        if (log.isDebugEnabled()) {
            log.debug("Attempting to GET resource: " + rawResourcePath);
        }

        URL[] resources = getRequestResourceURLs(request);

        if (resources == null || resources.length == 0) {
            if (log.isDebugEnabled()) {
                log.debug("Resource not found: " + rawResourcePath);
            }
            response.sendError(HttpServletResponse.SC_NOT_FOUND);
            return;
        }

        prepareResponse(response, resources, rawResourcePath);

        OutputStream out = selectOutputStream(request, response);

        try {
            for (int i = 0; i < resources.length; i++) {
                URLConnection resourceConn = resources[i].openConnection();
                resourceConn.setUseCaches(false);
                InputStream in = resourceConn.getInputStream();
                try {
                    byte[] buffer = new byte[1024];
                    int bytesRead = -1;
                    while ((bytesRead = in.read(buffer)) != -1) {
                        out.write(buffer, 0, bytesRead);
                    }
                } finally {
                    in.close();
                }
            }
        } finally {
            out.close();
        }
    }

    private OutputStream selectOutputStream(HttpServletRequest request, HttpServletResponse response)
            throws IOException {

        String acceptEncoding = request.getHeader("Accept-Encoding");
        String mimeType = response.getContentType();

        if (gzipEnabled && StringUtils.hasText(acceptEncoding) && acceptEncoding.indexOf("gzip") > -1
                && matchesCompressedMimeTypes(mimeType)) {
            log.debug("Enabling GZIP compression for the current response.");
            return new GZIPResponseStream(response);
        } else {
            return response.getOutputStream();
        }
    }

    private boolean matchesCompressedMimeTypes(String mimeType) {
        PathMatcher pathMatcher = new AntPathMatcher();
        Iterator<String> compressedMimeTypesIt = compressedMimeTypes.iterator();
        while (compressedMimeTypesIt.hasNext()) {
            String compressedMimeType = compressedMimeTypesIt.next();
            if (pathMatcher.match(compressedMimeType, mimeType)) {
                return true;
            }
        }
        return false;
    }

    private void prepareResponse(HttpServletResponse response, URL[] resources, String rawResourcePath)
            throws IOException {
        long lastModified = -1;
        int contentLength = 0;
        String mimeType = null;
        for (int i = 0; i < resources.length; i++) {
            URLConnection resourceConn = resources[i].openConnection();
            if (resourceConn.getLastModified() > lastModified) {
                lastModified = resourceConn.getLastModified();
            }

            String currentMimeType = getServletContext().getMimeType(resources[i].getPath());
            if (currentMimeType == null) {
                String extension = resources[i].getPath().substring(resources[i].getPath().lastIndexOf('.'));
                currentMimeType = (String) defaultMimeTypes.get(extension);
            }
            if (mimeType == null) {
                mimeType = currentMimeType;
            } else if (!mimeType.equals(currentMimeType)) {
                throw new MalformedURLException("Combined resource path: " + rawResourcePath
                        + " is invalid. All resources in a combined resource path must be of the same mime type.");
            }
            contentLength += resourceConn.getContentLength();
        }

        response.setContentType(mimeType);
        response.setHeader(HTTP_CONTENT_LENGTH_HEADER, Long.toString(contentLength));
        response.setDateHeader(HTTP_LAST_MODIFIED_HEADER, lastModified);
        if (cacheTimeout > 0) {
            configureCaching(response, cacheTimeout);
        }
    }

    protected long getLastModified(HttpServletRequest request) {
        if (log.isDebugEnabled()) {
            log.debug("Checking last modified of resource: " + request.getPathInfo());
        }
        URL[] resources;
        try {
            resources = getRequestResourceURLs(request);
        } catch (MalformedURLException e) {
            return -1;
        }

        if (resources == null || resources.length == 0) {
            return -1;
        }

        long lastModified = -1;

        for (int i = 0; i < resources.length; i++) {
            URLConnection resourceConn;
            try {
                resourceConn = resources[i].openConnection();
            } catch (IOException e) {
                return -1;
            }
            if (resourceConn.getLastModified() > lastModified) {
                lastModified = resourceConn.getLastModified();
            }
        }
        return lastModified;
    }

    private URL[] getRequestResourceURLs(HttpServletRequest request) throws MalformedURLException {

        String rawResourcePath = rawResourcePath(request);
        String appendedPaths = request.getParameter("appended");
        if (StringUtils.hasText(appendedPaths)) {
            rawResourcePath = rawResourcePath + "," + appendedPaths;
        }
        String[] localResourcePaths = StringUtils.delimitedListToStringArray(rawResourcePath, ",");
        URL[] resources = new URL[localResourcePaths.length];
        for (int i = 0; i < localResourcePaths.length; i++) {
            String localResourcePath = localResourcePaths[i];
            if (!isAllowed(localResourcePath)) {
                if (log.isWarnEnabled()) {
                    log.warn("An attempt to access a protected resource at " + localResourcePath
                            + " was disallowed.");
                }
                return null;
            }
            URL resource = getServletContext().getResource(localResourcePath);
            if (resource == null) {
                String jarResourcePath = jarPathPrefix + localResourcePath;
                if (!isAllowed(jarResourcePath)) {
                    if (log.isWarnEnabled()) {
                        log.warn("An attempt to access a protected resource at " + jarResourcePath
                                + " was disallowed.");
                    }
                    return null;
                }
                if (jarResourcePath.startsWith("/")) {
                    jarResourcePath = jarResourcePath.substring(1);
                }
                if (log.isDebugEnabled()) {
                    log.debug("Searching classpath for resource: " + jarResourcePath);
                }
                resource = ClassUtils.getDefaultClassLoader().getResource(jarResourcePath);
            }
            if (resource == null) {
                if (resources.length > 1) {
                    log.debug("Combined resource not found: " + localResourcePath);
                }
                return null;
            } else {
                resources[i] = resource;
            }
        }
        return resources;
    }

    private String rawResourcePath(HttpServletRequest request) {
        String rawResourcePath = request.getPathInfo();

        //FIXME test
        if (rawResourcePath == null && request instanceof ModuleHttpServletRequest) {
            ModuleHttpServletRequest moduleRequest = (ModuleHttpServletRequest) request;
            return moduleRequest.getModulePathInfo();
        }

        return rawResourcePath;
    }

    private boolean isAllowed(String resourcePath) {
        if (resourcePath.matches(protectedPath)) {
            return false;
        }
        PathMatcher pathMatcher = new AntPathMatcher();
        Iterator<String> allowedResourcePathsIt = allowedResourcePaths.iterator();
        while (allowedResourcePathsIt.hasNext()) {
            String pattern = allowedResourcePathsIt.next();
            if (pathMatcher.match(pattern, resourcePath)) {
                return true;
            }
        }
        return false;
    }

    /**
     * Set HTTP headers to allow caching for the given number of seconds.
     * @param seconds number of seconds into the future that the response should be cacheable for
     */
    private void configureCaching(HttpServletResponse response, int seconds) {
        // HTTP 1.0 header
        response.setDateHeader(HTTP_EXPIRES_HEADER, System.currentTimeMillis() + seconds * 1000L);
        // HTTP 1.1 header
        response.setHeader(HTTP_CACHE_CONTROL_HEADER, "max-age=" + seconds);
    }

    private class GZIPResponseStream extends ServletOutputStream {

        private ByteArrayOutputStream byteStream = null;

        private GZIPOutputStream gzipStream = null;

        private boolean closed = false;

        private HttpServletResponse response = null;

        private ServletOutputStream servletStream = null;

        public GZIPResponseStream(HttpServletResponse response) throws IOException {
            super();
            closed = false;
            this.response = response;
            this.servletStream = response.getOutputStream();
            byteStream = new ByteArrayOutputStream();
            gzipStream = new GZIPOutputStream(byteStream);
        }

        public void close() throws IOException {
            if (closed) {
                throw new IOException("This output stream has already been closed");
            }
            gzipStream.finish();

            byte[] bytes = byteStream.toByteArray();

            response.setContentLength(bytes.length);
            response.addHeader("Content-Encoding", "gzip");
            servletStream.write(bytes);
            servletStream.flush();
            servletStream.close();
            closed = true;
        }

        public void flush() throws IOException {
            if (closed) {
                throw new IOException("Cannot flush a closed output stream");
            }
            gzipStream.flush();
        }

        public void write(int b) throws IOException {
            if (closed) {
                throw new IOException("Cannot write to a closed output stream");
            }
            gzipStream.write((byte) b);
        }

        public void write(byte b[]) throws IOException {
            write(b, 0, b.length);
        }

        public void write(byte b[], int off, int len) throws IOException {
            if (closed) {
                throw new IOException("Cannot write to a closed output stream");
            }
            gzipStream.write(b, off, len);
        }

        @SuppressWarnings("unused")
        public boolean closed() {
            return (this.closed);
        }

        @SuppressWarnings("unused")
        public void reset() {
            // noop
        }
    }

    /**
     * Set whether to apply gzip compression to resources if the requesting client supports it.
     */
    public void setGzipEnabled(boolean gzipEnabled) {
        this.gzipEnabled = gzipEnabled;
    }

    /**
     * Set allowed resources as an comma separated String of URL patterns, e.g. "META-INF/** /*.js", The paths may be
     * any Ant-style pattern parsable by AntPathMatcher.
     * 
     * @see AntPathMatcher
     */
    public void setAllowedResourcePaths(String allowedResourcePaths) {
        this.allowedResourcePaths = new HashSet<String>(
                Arrays.asList(StringUtils.tokenizeToStringArray(allowedResourcePaths, ",", true, true)));
    }

    /**
     * Set comma separated MIME types that should have gzip compression applied. Typically, gzip compression is only
     * useful for text based content. Ant-style patterns are supported, e.g. "text/*".
    * 
    * @see AntPathMatcher
    */
    public void setCompressedMimeTypes(String compressedMimeTypes) {
        this.compressedMimeTypes = new HashSet<String>(
                Arrays.asList(StringUtils.tokenizeToStringArray(compressedMimeTypes, ",", true, true)));
    }

    /**
     * Set the default path prefix to apply to resources being served from jar files. Default is "META-INF".
     */
    public void setJarPathPrefix(String jarPathPrefix) {
        this.jarPathPrefix = jarPathPrefix;
    }

    /**
     * Set the number of seconds resources should be cached by the client. Zero disables caching. Default is one year.
     */
    public void setCacheTimeout(int cacheTimeout) {
        this.cacheTimeout = cacheTimeout;
    }

}