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Struts example source code file (DefaultStaticContentLoader.java)

This example Struts source code file (DefaultStaticContentLoader.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 - Struts tags/keywords

cache-control, calendar, expires, expires, httpservletrequest, httpservletresponse, if-modified-since, if-modified-since, io, ioexception, ioexception, network, request, response, servlet, string, string, stringtokenizer, url, util

The Struts DefaultStaticContentLoader.java source code

/*
 * $Id$
 *
 * 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.struts2.dispatcher;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.URL;
import java.net.URLDecoder;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.List;
import java.util.StringTokenizer;

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

import org.apache.struts2.StrutsConstants;
import org.apache.struts2.dispatcher.ng.HostConfig;
import org.apache.struts2.util.ClassLoaderUtils;

import com.opensymphony.xwork2.inject.Inject;
import com.opensymphony.xwork2.util.ClassLoaderUtil;
import com.opensymphony.xwork2.util.logging.Logger;
import com.opensymphony.xwork2.util.logging.LoggerFactory;

public class DefaultStaticContentLoader implements StaticContentLoader {
    /**
     * Provide a logging instance.
     */
    private Logger log;

    /**
     * Store set of path prefixes to use with static resources.
     */
    protected String[] pathPrefixes;

    /**
     * Store state of StrutsConstants.STRUTS_SERVE_STATIC_CONTENT setting.
     */
    protected boolean serveStatic;

    /**
     * Store state of StrutsConstants.STRUTS_SERVE_STATIC_BROWSER_CACHE setting.
     */
    protected boolean serveStaticBrowserCache;

    /**
     * Provide a formatted date for setting heading information when caching static content.
     */
    protected final Calendar lastModifiedCal = Calendar.getInstance();

    /**
     * Store state of StrutsConstants.STRUTS_I18N_ENCODING setting.
     */
    protected String encoding;


    /**
     * Modify state of StrutsConstants.STRUTS_SERVE_STATIC_CONTENT setting.
     *
     * @param val
     *            New setting
     */
    @Inject(StrutsConstants.STRUTS_SERVE_STATIC_CONTENT)
    public void setServeStaticContent(String val) {
        serveStatic = "true".equals(val);
    }

    /**
     * Modify state of StrutsConstants.STRUTS_SERVE_STATIC_BROWSER_CACHE
     * setting.
     *
     * @param val
     *            New setting
     */
    @Inject(StrutsConstants.STRUTS_SERVE_STATIC_BROWSER_CACHE)
    public void setServeStaticBrowserCache(String val) {
        serveStaticBrowserCache = "true".equals(val);
    }

    /**
     * Modify state of StrutsConstants.STRUTS_I18N_ENCODING setting.
     * @param val New setting
     */
    @Inject(StrutsConstants.STRUTS_I18N_ENCODING)
    public void setEncoding(String val) {
        encoding = val;
    }

    /*
     * (non-Javadoc)
     *
     * @see org.apache.struts2.dispatcher.StaticResourceLoader#setHostConfig(javax.servlet.FilterConfig)
     */
    public void setHostConfig(HostConfig filterConfig) {
        String param = filterConfig.getInitParameter("packages");
        String packages = getAdditionalPackages();
        if (param != null) {
            packages = param + " " + packages;
        }
        this.pathPrefixes = parse(packages);
        initLogging(filterConfig);
    }

    protected String getAdditionalPackages() {
        return "org.apache.struts2.static template org.apache.struts2.interceptor.debugging static";
    }

    /**
     * Create a string array from a comma-delimited list of packages.
     *
     * @param packages
     *            A comma-delimited String listing packages
     * @return A string array of packages
     */
    protected String[] parse(String packages) {
        if (packages == null) {
            return null;
        }
        List<String> pathPrefixes = new ArrayList();

        StringTokenizer st = new StringTokenizer(packages, ", \n\t");
        while (st.hasMoreTokens()) {
            String pathPrefix = st.nextToken().replace('.', '/');
            if (!pathPrefix.endsWith("/")) {
                pathPrefix += "/";
            }
            pathPrefixes.add(pathPrefix);
        }

        return pathPrefixes.toArray(new String[pathPrefixes.size()]);
    }

    /*
     * (non-Javadoc)
     *
     * @see org.apache.struts2.dispatcher.StaticResourceLoader#findStaticResource(java.lang.String,
     *      javax.servlet.http.HttpServletRequest,
     *      javax.servlet.http.HttpServletResponse)
     */
    public void findStaticResource(String path, HttpServletRequest request, HttpServletResponse response)
            throws IOException {
        String name = cleanupPath(path);
        for (String pathPrefix : pathPrefixes) {
            URL resourceUrl = findResource(buildPath(name, pathPrefix));
            if (resourceUrl != null) {
                InputStream is = null;
                try {
                    //check that the resource path is under the pathPrefix path
                    String pathEnding = buildPath(name, pathPrefix);
                    if (resourceUrl.getFile().endsWith(pathEnding))
                        is = resourceUrl.openStream();
                } catch (IOException ex) {
                    // just ignore it
                    continue;
                }

                //not inside the try block, as this could throw IOExceptions also
                if (is != null) {
                    process(is, path, request, response);
                    return;
                }
            }
        }

        response.sendError(HttpServletResponse.SC_NOT_FOUND);
    }

    protected void process(InputStream is, String path, HttpServletRequest request, HttpServletResponse response) throws IOException {
        if (is != null) {
            Calendar cal = Calendar.getInstance();

            // check for if-modified-since, prior to any other headers
            long ifModifiedSince = 0;
            try {
                ifModifiedSince = request.getDateHeader("If-Modified-Since");
            } catch (Exception e) {
                log.warn("Invalid If-Modified-Since header value: '"
                        + request.getHeader("If-Modified-Since") + "', ignoring");
            }
            long lastModifiedMillis = lastModifiedCal.getTimeInMillis();
            long now = cal.getTimeInMillis();
            cal.add(Calendar.DAY_OF_MONTH, 1);
            long expires = cal.getTimeInMillis();

            if (ifModifiedSince > 0 && ifModifiedSince <= lastModifiedMillis) {
                // not modified, content is not sent - only basic
                // headers and status SC_NOT_MODIFIED
                response.setDateHeader("Expires", expires);
                response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
                is.close();
                return;
            }

            // set the content-type header
            String contentType = getContentType(path);
            if (contentType != null) {
                response.setContentType(contentType);
            }

            if (serveStaticBrowserCache) {
                // set heading information for caching static content
                response.setDateHeader("Date", now);
                response.setDateHeader("Expires", expires);
                response.setDateHeader("Retry-After", expires);
                response.setHeader("Cache-Control", "public");
                response.setDateHeader("Last-Modified", lastModifiedMillis);
            } else {
                response.setHeader("Cache-Control", "no-cache");
                response.setHeader("Pragma", "no-cache");
                response.setHeader("Expires", "-1");
            }

            try {
                copy(is, response.getOutputStream());
            } finally {
                is.close();
            }
            return;
        }
    }

    private void initLogging(HostConfig filterConfig) {
        String factoryName = filterConfig.getInitParameter("loggerFactory");
        if (factoryName != null) {
            try {
                Class cls = ClassLoaderUtils.loadClass(factoryName, this.getClass());
                LoggerFactory fac = (LoggerFactory)cls.newInstance();
                LoggerFactory.setLoggerFactory(fac);
            } catch (InstantiationException e) {
                System.err.println("Unable to instantiate logger factory: "+factoryName+", using default");
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                System.err.println("Unable to access logger factory: "+factoryName+", using default");
                e.printStackTrace();
            } catch (ClassNotFoundException e) {
                System.err.println("Unable to locate logger factory class: "+factoryName+", using default");
                e.printStackTrace();
            }
        }

        log = LoggerFactory.getLogger(FilterDispatcher.class);

    }

    /**
     * Look for a static resource in the classpath.
     *
     * @param path The resource path
     * @return The inputstream of the resource
     * @throws IOException If there is a problem locating the resource
     */
    protected URL findResource(String path) throws IOException {
        return ClassLoaderUtil.getResource(path, getClass());
    }

    /**
     * @param name resource name
     * @param packagePrefix The package prefix to use to locate the resource
     * @return full path
     * @throws UnsupportedEncodingException
     * @throws IOException
     */
    protected String buildPath(String name, String packagePrefix) throws UnsupportedEncodingException {
        String resourcePath;
        if (packagePrefix.endsWith("/") && name.startsWith("/")) {
            resourcePath = packagePrefix + name.substring(1);
        } else {
            resourcePath = packagePrefix + name;
        }

        return URLDecoder.decode(resourcePath, encoding);
    }



    /**
     * Determine the content type for the resource name.
     *
     * @param name The resource name
     * @return The mime type
     */
    protected String getContentType(String name) {
        // NOT using the code provided activation.jar to avoid adding yet another dependency
        // this is generally OK, since these are the main files we server up
        if (name.endsWith(".js")) {
            return "text/javascript";
        } else if (name.endsWith(".css")) {
            return "text/css";
        } else if (name.endsWith(".html")) {
            return "text/html";
        } else if (name.endsWith(".txt")) {
            return "text/plain";
        } else if (name.endsWith(".gif")) {
            return "image/gif";
        } else if (name.endsWith(".jpg") || name.endsWith(".jpeg")) {
            return "image/jpeg";
        } else if (name.endsWith(".png")) {
            return "image/png";
        } else {
            return null;
        }
    }

    /**
     * Copy bytes from the input stream to the output stream.
     *
     * @param input
     *            The input stream
     * @param output
     *            The output stream
     * @throws IOException
     *             If anything goes wrong
     */
    protected void copy(InputStream input, OutputStream output) throws IOException {
        final byte[] buffer = new byte[4096];
        int n;
        while (-1 != (n = input.read(buffer))) {
            output.write(buffer, 0, n);
        }
        output.flush();
    }

    public boolean canHandle(String resourcePath) {
        return serveStatic && (resourcePath.startsWith("/struts") || resourcePath.startsWith("/static"));
    }

    /**
     * @param path requested path
     * @return path without leading "/struts" or "/static"
     */
    protected String cleanupPath(String path) {
        //path will start with "/struts" or "/static", remove them
        return path.substring(7);
    }
}

Other Struts examples (source code examples)

Here is a short list of links related to this Struts DefaultStaticContentLoader.java source code file:

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