templatecache.java

freemaker安装软件

/*
 * Copyright (c) 2003 The Visigoth Software Society. All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowledgement:
 *       "This product includes software developed by the
 *        Visigoth Software Society (http://www.visigoths.org/)."
 *    Alternately, this acknowledgement may appear in the software itself,
 *    if and wherever such third-party acknowledgements normally appear.
 *
 * 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the
 *    project contributors may be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact [e-mail].
 *
 * 5. Products derived from this software may not be called "FreeMarker" or "Visigoth"
 *    nor may "FreeMarker" or "Visigoth" appear in their names
 *    without prior written permission of the Visigoth Software Society.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE VISIGOTH SOFTWARE SOCIETY OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Visigoth Software Society. For more
 * information on the Visigoth Software Society, please see
 * http://www.visigoths.org/
 */

package freemarker.cache;

import java.io.IOException;
import java.io.Reader;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
import java.util.StringTokenizer;

import freemarker.core.Environment;
import freemarker.log.Logger;
import freemarker.template.Configuration;
import freemarker.template.Template;

/**
 * A class that performs caching and on-demand loading of the templates.
 * The actual loading is delegated to a {@link TemplateLoader}. Also,
 * various constructors provide you with convenient caches with predefined
 * behavior. Typically you don't use this class directly - in normal
 * circumstances it is hidden behind a {@link Configuration}.
 * @author Attila Szegedi, szegedia at freemail dot hu
 * @version $Id: TemplateCache.java,v 1.62.2.1 2006/04/19 14:29:59 szegedia Exp $
 */
public class TemplateCache
{
    private static final String ASTERISKSTR = "*";
    private static final String LOCALE_SEPARATOR = "_";
    private static final char ASTERISK = '*';
    private static final String CURRENT_DIR_PATH_PREFIX = "./";
    private static final String CURRENT_DIR_PATH = "/./";
    private static final String PARENT_DIR_PATH_PREFIX = "../";
    private static final String PARENT_DIR_PATH = "/../";
    private static final char SLASH = '/';
    private static final Logger logger = Logger.getLogger("freemarker.cache");

    private final TemplateLoader mainLoader;
        /** DD: [noFallback]
        , 
        fallbackTemplateLoader = new ClassTemplateLoader(TemplateCache.class, "/");
        */
    /** Here we keep our cached templates */
    private final CacheStorage storage;
    /** The default refresh delay in milliseconds. */
    private long delay = 5000;
    /** Specifies if localized template lookup is enabled or not */
    private boolean localizedLookup = true;

    private Configuration config;

    /**
     * Returns a template cache that will first try to load a template from
     * the file system relative to the current user directory (i.e. the value
     * of the system property <code>user.dir</code>), then from the classpath.
     * This default template cache suits many applications.
     */
    public TemplateCache()
    {
        this(createDefaultTemplateLoader());
    }

    private static TemplateLoader createDefaultTemplateLoader() {
        try {
            return new FileTemplateLoader();
        } catch(Exception e) {
            logger.warn("Could not create a file template loader for current directory", e);
            return null;
        }
    }
    
    /**
     * Creates a new template cache with a custom template loader that is used
     * to load the templates.
     * @param loader the template loader to use.
     */
    public TemplateCache(TemplateLoader loader)
    {
        this(loader, new MruCacheStorage(0, Integer.MAX_VALUE));
    }

    /**
     * Creates a new template cache with a custom template loader that is used
     * to load the templates.
     * @param loader the template loader to use.
     */
    public TemplateCache(TemplateLoader loader, CacheStorage storage)
    {
        this.mainLoader = loader;
        this.storage = storage;
        if(storage == null) 
        {
            throw new IllegalArgumentException("storage == null");
        }
    }

    /**
     * Sets the configuration object to which this cache belongs. This
     * method is called by the configuration itself to establish the
     * relation, and should not be called by users.
     */
    public void setConfiguration(Configuration config)
    {
        this.config = config;
        clear();
    }

    public TemplateLoader getTemplateLoader()
    {
        return mainLoader;
    }
    
    public CacheStorage getCacheStorage()
    {
        return storage;
    }
    
    /**
     * Loads a template with the given name, in the specified locale and
     * using the specified character encoding.
     *
     * @param name the name of the template. Can't be null. The exact syntax of the name
     * is interpreted by the underlying {@link TemplateLoader}, but the
     * cache makes some assumptions. First, the name is expected to be
     * a hierarchical path, with path components separated by a slash
     * character (not with backslash!). The path (the name) must <em>not</em> begin with slash;
     * the path is always relative to the "template root directory".
     * Then, the <tt>..</tt> and <tt>.</tt> path metaelements will be resolved.
     * For example, if the name is <tt>a/../b/./c.ftl</tt>, then it will be
     * simplified to <tt>b/c.ftl</tt>. The rules regarding this are same as with conventional
     * UN*X paths. The path must not reach outside the template root directory, that is,
     * it can't be something like <tt>"../templates/my.ftl"</tt> (not even if the pervious path
     * happens to be equivalent with <tt>"/my.ftl"</tt>).
     * Further, the path is allowed to contain at most
     * one path element whose name is <tt>*</tt> (asterisk). This path metaelement triggers the
     * <i>acquisition mechanism</i>. If the template is not found in
     * the location described by the concatenation of the path left to the
     * asterisk (called base path) and the part to the right of the asterisk
     * (called resource path), the cache will attempt to remove the rightmost
     * path component from the base path ("go up one directory") and concatenate
     * that with the resource path. The process is repeated until either a
     * template is found, or the base path is completely exhausted.
     *
     * @param locale the requested locale of the template. Can't be null.
     * Assuming you have specified <code>en_US</code> as the locale and
     * <code>myTemplate.html</code> as the name of the template, the cache will
     * first try to retrieve <code>myTemplate_en_US.html</code>, then
     * <code>myTemplate.html_en.html</code>, and finally
     * <code>myTemplate.html</code>.
     *
     * @param encoding the character encoding used to interpret the template
     * source bytes. Can't be null.
     *
     * @param parse if true, the loaded template is parsed and interpreted
     * as a regular FreeMarker template. If false, the loaded template is
     * treated as an unparsed block of text.
     *
     * @return the loaded template, or null if the template is not found.
     */
    public Template getTemplate(String name, Locale locale, String encoding, boolean parse)
    throws IOException
    {
        if (name == null) {
            throw new IllegalArgumentException("Argument \"name\" can't be null");
        }
        if (locale == null) {
            throw new IllegalArgumentException("Argument \"locale\" can't be null");
        }
        if (encoding == null) {
            throw new IllegalArgumentException("Argument \"encoding\" can't be null");
        }
        name = normalizeName(name);
        if(name == null) {
            return null;
        }
        Template result = null;
        if (mainLoader != null) {
            result = getTemplate(mainLoader, name, locale, encoding, parse);
        }
        /** DD: [noFallback]
        if (result == null && name.toLowerCase().endsWith(".ftl")) {
            result = getTemplate(fallbackTemplateLoader, name, locale, encoding, parse);
        }
        */
        return result;
    }    
    
    private Template getTemplate(TemplateLoader loader, String name, Locale locale, String encoding, boolean parse)
    throws IOException
    {
        boolean debug = logger.isDebugEnabled();
        String debugName = debug ? name + "[" + locale + "," + encoding + (parse ? ",parsed] " : ",unparsed] ") : null;
        TemplateKey tk = new TemplateKey(name, locale, encoding, parse);
        synchronized (storage)
        {
            CachedTemplate cachedTemplate = (CachedTemplate)storage.get(tk);
            long now = System.currentTimeMillis();
            long lastModified = -1L;
            Object newlyFoundSource = null;
            try
            {
                if (cachedTemplate != null)
                {
                    // If we're within the refresh delay, return the cached copy
                    if (now - cachedTemplate.lastChecked < delay)
                    {
                        if(debug)
                        {
                            logger.debug(debugName + "cached copy not yet stale; using cached.");
                        }
                        return cachedTemplate.template;
                    }
                    // Else, update the last-checked flag
                    cachedTemplate.lastChecked = now;

                    // Find the template source
                    newlyFoundSource = findTemplateSource(name, locale);

                    // Template source was removed
                    if (newlyFoundSource == null)
                    {
                        if(debug)
                        {
                            logger.debug(debugName + "no source found (removing from cache if it was cached).");
                        } 
                        storage.remove(tk);
                        return null;
                    }

                    // If the source didn't change and its last modified date
                    // also didn't change, return the cached version.
                    lastModified = loader.getLastModified(newlyFoundSource);
                    boolean lastModifiedNotChanged = lastModified == cachedTemplate.lastModified;
                    boolean sourceEquals = newlyFoundSource.equals(cachedTemplate.source);
                    if(lastModifiedNotChanged && sourceEquals)
                    {
                        if(debug)
                        {
                            logger.debug(debugName + "using cached since " + 
                                    newlyFoundSource + " didn't change.");
                        } 
                        cachedTemplate.lastChecked = now;
                        return cachedTemplate.template;
                    }
                    else
                    {
                        if(debug && !sourceEquals)
                        {
                            logger.debug("Updating source, info for cause: " + 
                                "sourceEquals=" + sourceEquals + 
                                ", newlyFoundSource=" + newlyFoundSource + 
                                ", cachedTemplate.source=" + cachedTemplate.source);
                        }
                        if(debug && !lastModifiedNotChanged)
                        {
                            logger.debug("Updating source, info for cause: " + 
                                "lastModifiedNotChanged=" + lastModifiedNotChanged + 
                                ", cache lastModified=" + cachedTemplate.lastModified + 
                                " != file lastModified=" + lastModified);
                        }
                        // Update the source
                        cachedTemplate.source = newlyFoundSource;
                    }
                }
                else
                {
                    if(debug) 
                    {
                        logger.debug("Could not find template in cache, "
                            + "creating new one; id=[" + 
                            tk.name + "[" + tk.locale + "," + tk.encoding + 
                            (tk.parse ? ",parsed] " : ",unparsed] ") + "]");
                    }
                    
                    // Construct a new CachedTemplate entry. Note we set the
                    // cachedTemplate.lastModified to Long.MIN_VALUE. This is
                    // a flag that signs it has to be explicitly queried later on.
                    newlyFoundSource = findTemplateSource(name, locale);
                    if (newlyFoundSource == null)
                    {
                        return null;
                    }
                    cachedTemplate = new CachedTemplate();
                    cachedTemplate.source = newlyFoundSource;
                    cachedTemplate.lastChecked = now;
                    cachedTemplate.lastModified = lastModified = Long.MIN_VALUE;
                    storage.put(tk, cachedTemplate);
                }