servletcacheadministrator.java

来自「一个不错的cache」· Java 代码 · 共 744 行 · 第 1/2 页

    }

    /**
    * Register a listener for Cache Map events.
    *
    * @param listener  The object that listens to events.
    */
    public void addScopeEventListener(ScopeEventListener listener) {
        listenerList.add(ScopeEventListener.class, listener);
    }

    /**
    * Cancels a pending cache update. This should only be called by a thread
    * that received a {@link NeedsRefreshException} and was unable to generate
    * some new cache content.
    *
    * @param scope The cache scope
    * @param request The servlet request
    * @param key The cache entry key to cancel the update of.
    */
    public void cancelUpdate(int scope, HttpServletRequest request, String key) {
        Cache cache = getCache(request, scope);
        key = this.generateEntryKey(key, request, scope);
        cache.cancelUpdate(key);
    }

    /**
    * Flush all scopes at a particular time
    *
    * @param date The time to flush the scope
    */
    public void flushAll(Date date) {
        synchronized (flushTimes) {
            setFlushTime(date, PageContext.APPLICATION_SCOPE);
            setFlushTime(date, PageContext.SESSION_SCOPE);
            setFlushTime(date, PageContext.REQUEST_SCOPE);
            setFlushTime(date, PageContext.PAGE_SCOPE);
        }

        // Trigger a flushAll event
        dispatchScopeEvent(ScopeEventType.ALL_SCOPES_FLUSHED, -1, date, null);
    }

    /**
    * Flush all scopes instantly.
    */
    public void flushAll() {
        flushAll(new Date());
    }

    /**
    * Generates a cache entry key.
    *
    * If the string key is not specified, the HTTP request URI and QueryString is used.
    * Operating systems that have a filename limitation less than 255 or have
    * filenames that are case insensitive may have issues with key generation where
    * two distinct pages map to the same key.
    * <p>
    * POST Requests (which have no distinguishing
    * query string) may also generate identical keys for what is actually different pages.
    * In these cases, specify an explicit key attribute for the CacheTag.
    *
    * @param key The key entered by the user
    * @param request The current request
    * @param scope The scope this cache entry is under
    * @return The generated cache key
    */
    public String generateEntryKey(String key, HttpServletRequest request, int scope) {
        return generateEntryKey(key, request, scope, null, null);
    }

    /**
    * Generates a cache entry key.
    *
    * If the string key is not specified, the HTTP request URI and QueryString is used.
    * Operating systems that have a filename limitation less than 255 or have
    * filenames that are case insensitive may have issues with key generation where
    * two distinct pages map to the same key.
    * <p>
    * POST Requests (which have no distinguishing
    * query string) may also generate identical keys for what is actually different pages.
    * In these cases, specify an explicit key attribute for the CacheTag.
    *
    * @param key The key entered by the user
    * @param request The current request
    * @param scope The scope this cache entry is under
    * @param language The ISO-639 language code to distinguish different pages in application scope
    * @return The generated cache key
    */
    public String generateEntryKey(String key, HttpServletRequest request, int scope, String language) {
        return generateEntryKey(key, request, scope, language, null);
    }

    /**
    * Generates a cache entry key.
    * <p>
    * If the string key is not specified, the HTTP request URI and QueryString is used.
    * Operating systems that have a filename limitation less than 255 or have
    * filenames that are case insensitive may have issues with key generation where
    * two distinct pages map to the same key.
    * <p>
    * POST Requests (which have no distinguishing
    * query string) may also generate identical keys for what is actually different pages.
    * In these cases, specify an explicit key attribute for the CacheTag.
    *
    * @param key The key entered by the user
    * @param request The current request
    * @param scope The scope this cache entry is under
    * @param language The ISO-639 language code to distinguish different pages in application scope
    * @param suffix The ability to put a suffix at the end of the key
    * @return The generated cache key
    */
    public String generateEntryKey(String key, HttpServletRequest request, int scope, String language, String suffix) {
        /**
        * Used for generating cache entry keys.
        */
        StringBuffer cBuffer = new StringBuffer(AVERAGE_KEY_LENGTH);

        // Append the language if available
        if (language != null) {
            cBuffer.append(FILE_SEPARATOR).append(language);
        }

        // Servers for multiple host domains need this distinction in the key
        if (useHostDomainInKey) {
            cBuffer.append(FILE_SEPARATOR).append(request.getServerName());
        }

        if (key != null) {
            cBuffer.append(FILE_SEPARATOR).append(key);
        } else {
            String generatedKey = request.getRequestURI();

            if (generatedKey.charAt(0) != FILE_SEPARATOR_CHAR) {
                cBuffer.append(FILE_SEPARATOR_CHAR);
            }

            cBuffer.append(generatedKey);
            cBuffer.append("_").append(request.getMethod()).append("_");

            generatedKey = getSortedQueryString(request);

            if (generatedKey != null) {
                try {
                    java.security.MessageDigest digest = java.security.MessageDigest.getInstance("MD5");
                    byte[] b = digest.digest(generatedKey.getBytes());
                    cBuffer.append("_");

                    // Base64 encoding allows for unwanted slash characters.
                    cBuffer.append(toBase64(b).replace('/', '_'));
                } catch (Exception e) {
                    // Ignore query string
                }
            }
        }

        // Do we want a suffix
        if ((suffix != null) && (suffix.length() > 0)) {
            cBuffer.append(suffix);
        }

        return cBuffer.toString();
    }

    /**
    * Creates a string that contains all of the request parameters and their
    * values in a single string. This is very similar to
    * <code>HttpServletRequest.getQueryString()</code> except the parameters are
    * sorted by name, and if there is a <code>jsessionid</code> parameter it is
    * filtered out.<p>
    * If the request has no parameters, this method returns <code>null</code>.
    */
    protected String getSortedQueryString(HttpServletRequest request) {
        Map paramMap = request.getParameterMap();

        if (paramMap.isEmpty()) {
            return null;
        }

        Set paramSet = new TreeMap(paramMap).entrySet();

        StringBuffer buf = new StringBuffer();

        boolean first = true;

        for (Iterator it = paramSet.iterator(); it.hasNext();) {
            Map.Entry entry = (Map.Entry) it.next();
            String[] values = (String[]) entry.getValue();

            for (int i = 0; i < values.length; i++) {
                String key = (String) entry.getKey();

                if ((key.length() != 10) || !"jsessionid".equals(key)) {
                    if (first) {
                        first = false;
                    } else {
                        buf.append('&');
                    }

                    buf.append(key).append('=').append(values[i]);
                }
            }
        }

        // We get a 0 length buffer if the only parameter was a jsessionid
        if (buf.length() == 0) {
            return null;
        } else {
            return buf.toString();
        }
    }

    /**
    * Log error messages to commons logging.
    *
    * @param message   Message to log.
    */
    public void logError(String message) {
        log.error("[oscache]: " + message);
    }

    /**
    * Put an object in the cache
    *
    * @param scope The cache scope
    * @param request The servlet request
    * @param key The object key
    * @param content The object to add
    */
    public void putInCache(int scope, HttpServletRequest request, String key, Object content) {
        putInCache(scope, request, key, content, null);
    }

    /**
    * Put an object in the cache
    *
    * @param scope The cache scope
    * @param request The servlet request
    * @param key The object key
    * @param content The object to add
    * @param policy The refresh policy
    */
    public void putInCache(int scope, HttpServletRequest request, String key, Object content, EntryRefreshPolicy policy) {
        Cache cache = getCache(request, scope);
        key = this.generateEntryKey(key, request, scope);
        cache.putInCache(key, content, policy);
    }

    /**
    * Sets the cache capacity (number of items). If the cache contains
    * more than <code>capacity</code> items then items will be removed
    * to bring the cache back down to the new size.
    *
    * @param scope The cache scope
    * @param request The servlet request
    * @param capacity The new capacity
    */
    public void setCacheCapacity(int scope, HttpServletRequest request, int capacity) {
        setCacheCapacity(capacity);
        getCache(request, scope).setCapacity(capacity);
    }

    /**
    * Unregister a listener for Cache Map events.
    *
    * @param listener  The object that currently listens to events.
    */
    public void removeScopeEventListener(ScopeEventListener listener) {
        listenerList.remove(ScopeEventListener.class, listener);
    }

    /**
    * Finalizes all the listeners that are associated with the given cache object
    */
    protected void finalizeListeners(Cache cache) {
        super.finalizeListeners(cache);
    }

    /**
    * Convert a byte array into a Base64 string (as used in mime formats)
    */
    private static String toBase64(byte[] aValue) {
        int byte1;
        int byte2;
        int byte3;
        int iByteLen = aValue.length;
        StringBuffer tt = new StringBuffer();

        for (int i = 0; i < iByteLen; i += 3) {
            boolean bByte2 = (i + 1) < iByteLen;
            boolean bByte3 = (i + 2) < iByteLen;
            byte1 = aValue[i] & 0xFF;
            byte2 = (bByte2) ? (aValue[i + 1] & 0xFF) : 0;
            byte3 = (bByte3) ? (aValue[i + 2] & 0xFF) : 0;

            tt.append(m_strBase64Chars.charAt(byte1 / 4));
            tt.append(m_strBase64Chars.charAt((byte2 / 16) + ((byte1 & 0x3) * 16)));
            tt.append(((bByte2) ? m_strBase64Chars.charAt((byte3 / 64) + ((byte2 & 0xF) * 4)) : '='));
            tt.append(((bByte3) ? m_strBase64Chars.charAt(byte3 & 0x3F) : '='));
        }

        return tt.toString();
    }

    /**
    * Create a cache
    *
    * @param scope The cache scope
    * @param sessionId The sessionId for with the cache will be created
    * @return A new cache
    */
    private ServletCache createCache(int scope, String sessionId) {
        ServletCache newCache = new ServletCache(this, algorithmClass, cacheCapacity, scope);

        // TODO - Fix me please!
        // Hack! This is nasty - if two sessions are created within a short
        // space of time it is possible they will end up with duplicate
        // session IDs being passed to the DiskPersistenceListener!...
        config.set(HASH_KEY_SCOPE, "" + scope);
        config.set(HASH_KEY_SESSION_ID, sessionId);

        newCache = (ServletCache) configureStandardListeners(newCache);

        if (config.getProperty(CACHE_ENTRY_EVENT_LISTENERS_KEY) != null) {
            // Add any event listeners that have been specified in the configuration
            CacheEventListener[] listeners = getCacheEventListeners();

            for (int i = 0; i < listeners.length; i++) {
                if (listeners[i] instanceof ScopeEventListener) {
                    newCache.addCacheEventListener(listeners[i], ScopeEventListener.class);
                }
            }
        }

        return newCache;
    }

    /**
    * Dispatch a scope event to all registered listeners.
    *
    * @param eventType   The type of event
    * @param scope       Scope that was flushed (Does not apply for FLUSH_ALL event)
    * @param date        Date of flushing
    * @param origin      The origin of the event
    */
    private void dispatchScopeEvent(ScopeEventType eventType, int scope, Date date, String origin) {
        // Create the event
        ScopeEvent event = new ScopeEvent(eventType, scope, date, origin);

        // Guaranteed to return a non-null array
        Object[] listeners = listenerList.getListenerList();

        // Process the listeners last to first, notifying
        // those that are interested in this event
        for (int i = listeners.length - 2; i >= 0; i -= 2) {
            if (listeners[i] == ScopeEventListener.class) {
                ((ScopeEventListener) listeners[i + 1]).scopeFlushed(event);
            }
        }
    }

    /**
    *        Set property cache.use.host.domain.in.key=true to add domain information to key
    *  generation for hosting multiple sites
    */
    private void initHostDomainInKey() {
        String propStr = getProperty(CACHE_USE_HOST_DOMAIN_KEY);

        useHostDomainInKey = "true".equalsIgnoreCase(propStr);
    }
}