proxydircontext.java

业界著名的tomcat服务器的最新6.0的源代码。

    /**
     * Searches in the named context or object for entries that satisfy the 
     * given search filter. Performs the search as specified by the search 
     * controls.
     * 
     * @param name the name of the context or object to search
     * @param filterExpr the filter expression to use for the search. 
     * The expression may contain variables of the form "{i}" where i is a 
     * nonnegative integer. May not be null.
     * @param filterArgs the array of arguments to substitute for the 
     * variables in filterExpr. The value of filterArgs[i] will replace each 
     * occurrence of "{i}". If null, equivalent to an empty array.
     * @param cons the search controls that control the search. If null, the 
     * default search controls are used (equivalent to (new SearchControls())).
     * @return an enumeration of SearchResults of the objects that satisy the 
     * filter; never null
     * @exception ArrayIndexOutOfBoundsException if filterExpr contains {i} 
     * expressions where i is outside the bounds of the array filterArgs
     * @exception InvalidSearchControlsException if cons contains invalid 
     * settings
     * @exception InvalidSearchFilterException if filterExpr with filterArgs 
     * represents an invalid search filter
     * @exception NamingException if a naming exception is encountered
     */
    public NamingEnumeration search(Name name, String filterExpr,
                                    Object[] filterArgs, SearchControls cons)
        throws NamingException {
        return dirContext.search(parseName(name), filterExpr, filterArgs, 
                                 cons);
    }


    /**
     * Searches in the named context or object for entries that satisfy the 
     * given search filter. Performs the search as specified by the search 
     * controls.
     * 
     * @param name the name of the context or object to search
     * @param filterExpr the filter expression to use for the search. 
     * The expression may contain variables of the form "{i}" where i is a 
     * nonnegative integer. May not be null.
     * @param filterArgs the array of arguments to substitute for the 
     * variables in filterExpr. The value of filterArgs[i] will replace each 
     * occurrence of "{i}". If null, equivalent to an empty array.
     * @param cons the search controls that control the search. If null, the 
     * default search controls are used (equivalent to (new SearchControls())).
     * @return an enumeration of SearchResults of the objects that satisy the 
     * filter; never null
     * @exception ArrayIndexOutOfBoundsException if filterExpr contains {i} 
     * expressions where i is outside the bounds of the array filterArgs
     * @exception InvalidSearchControlsException if cons contains invalid 
     * settings
     * @exception InvalidSearchFilterException if filterExpr with filterArgs 
     * represents an invalid search filter
     * @exception NamingException if a naming exception is encountered
     */
    public NamingEnumeration search(String name, String filterExpr,
                                    Object[] filterArgs, SearchControls cons)
        throws NamingException {
        return dirContext.search(parseName(name), filterExpr, filterArgs, 
                                 cons);
    }


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


    /**
     * Retrieves the named object as a cache entry, without any exception.
     * 
     * @param name the name of the object to look up
     * @return the cache entry bound to name
     */
    public CacheEntry lookupCache(String name) {
        CacheEntry entry = cacheLookup(name);
        if (entry == null) {
            entry = new CacheEntry();
            entry.name = name;
            try {
                Object object = dirContext.lookup(parseName(name));
                if (object instanceof InputStream) {
                    entry.resource = new Resource((InputStream) object);
                } else if (object instanceof DirContext) {
                    entry.context = (DirContext) object;
                } else if (object instanceof Resource) {
                    entry.resource = (Resource) object;
                } else {
                    entry.resource = new Resource(new ByteArrayInputStream
                        (object.toString().getBytes()));
                }
                Attributes attributes = dirContext.getAttributes(parseName(name));
                if (!(attributes instanceof ResourceAttributes)) {
                    attributes = new ResourceAttributes(attributes);
                }
                entry.attributes = (ResourceAttributes) attributes;
            } catch (NamingException e) {
                entry.exists = false;
            }
        }
        return entry;
    }


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


    /**
     * Parses a name.
     * 
     * @return the parsed name
     */
    protected String parseName(String name) 
        throws NamingException {
        return name;
    }


    /**
     * Parses a name.
     * 
     * @return the parsed name
     */
    protected Name parseName(Name name) 
        throws NamingException {
        return name;
    }


    /**
     * Lookup in cache.
     */
    protected CacheEntry cacheLookup(String name) {
        if (cache == null)
            return (null);
        if (name == null)
            name = "";
        for (int i = 0; i < nonCacheable.length; i++) {
            if (name.startsWith(nonCacheable[i])) {
                return (null);
            }
        }
        CacheEntry cacheEntry = cache.lookup(name);
        if (cacheEntry == null) {
            cacheEntry = new CacheEntry();
            cacheEntry.name = name;
            // Load entry
            cacheLoad(cacheEntry);
        } else {
            if (!validate(cacheEntry)) {
                if (!revalidate(cacheEntry)) {
                    cacheUnload(cacheEntry.name);
                    return (null);
                } else {
                    cacheEntry.timestamp = 
                        System.currentTimeMillis() + cacheTTL;
                }
            }
            cacheEntry.accessCount++;
        }
        return (cacheEntry);
    }


    /**
     * Validate entry.
     */
    protected boolean validate(CacheEntry entry) {
        if (((!entry.exists)
             || (entry.context != null)
             || ((entry.resource != null) 
                 && (entry.resource.getContent() != null)))
            && (System.currentTimeMillis() < entry.timestamp)) {
            return true;
        }
        return false;
    }


    /**
     * Revalidate entry.
     */
    protected boolean revalidate(CacheEntry entry) {
        // Get the attributes at the given path, and check the last 
        // modification date
        if (!entry.exists)
            return false;
        if (entry.attributes == null)
            return false;
        long lastModified = entry.attributes.getLastModified();
        long contentLength = entry.attributes.getContentLength();
        if (lastModified <= 0)
            return false;
        try {
            Attributes tempAttributes = dirContext.getAttributes(entry.name);
            ResourceAttributes attributes = null;
            if (!(tempAttributes instanceof ResourceAttributes)) {
                attributes = new ResourceAttributes(tempAttributes);
            } else {
                attributes = (ResourceAttributes) tempAttributes;
            }
            long lastModified2 = attributes.getLastModified();
            long contentLength2 = attributes.getContentLength();
            return (lastModified == lastModified2) 
                && (contentLength == contentLength2);
        } catch (NamingException e) {
            return false;
        }
    }


    /**
     * Load entry into cache.
     */
    protected void cacheLoad(CacheEntry entry) {

        String name = entry.name;

        // Retrieve missing info
        boolean exists = true;

        // Retrieving attributes
        if (entry.attributes == null) {
            try {
                Attributes attributes = dirContext.getAttributes(entry.name);
                if (!(attributes instanceof ResourceAttributes)) {
                    entry.attributes = 
                        new ResourceAttributes(attributes);
                } else {
                    entry.attributes = (ResourceAttributes) attributes;
                }
            } catch (NamingException e) {
                exists = false;
            }
        }

        // Retriving object
        if ((exists) && (entry.resource == null) && (entry.context == null)) {
            try {
                Object object = dirContext.lookup(name);
                if (object instanceof InputStream) {
                    entry.resource = new Resource((InputStream) object);
                } else if (object instanceof DirContext) {
                    entry.context = (DirContext) object;
                } else if (object instanceof Resource) {
                    entry.resource = (Resource) object;
                } else {
                    entry.resource = new Resource(new ByteArrayInputStream
                        (object.toString().getBytes()));
                }
            } catch (NamingException e) {
                exists = false;
            }
        }

        // Load object content
        if ((exists) && (entry.resource != null) 
            && (entry.resource.getContent() == null) 
            && (entry.attributes.getContentLength() >= 0)
            && (entry.attributes.getContentLength() < 
                (cacheObjectMaxSize * 1024))) {
            int length = (int) entry.attributes.getContentLength();
            // The entry size is 1 + the resource size in KB, if it will be 
            // cached
            entry.size += (entry.attributes.getContentLength() / 1024);
            InputStream is = null;
            try {
                is = entry.resource.streamContent();
                int pos = 0;
                byte[] b = new byte[length];
                while (pos < length) {
                    int n = is.read(b, pos, length - pos);
                    if (n < 0)
                        break;
                    pos = pos + n;
                }
                entry.resource.setContent(b);
            } catch (IOException e) {
                ; // Ignore
            } finally {
                try {
                    if (is != null)
                        is.close();
                } catch (IOException e) {
                    ; // Ignore
                }
            }
        }

        // Set existence flag
        entry.exists = exists;

        // Set timestamp
        entry.timestamp = System.currentTimeMillis() + cacheTTL;

        // Add new entry to cache
        synchronized (cache) {
            // Check cache size, and remove elements if too big
            if ((cache.lookup(name) == null) && cache.allocate(entry.size)) {
                cache.load(entry);
            }
        }

    }


    /**
     * Remove entry from cache.
     */
    protected boolean cacheUnload(String name) {
        if (cache == null)
            return false;
        synchronized (cache) {
            return cache.unload(name);
        }
    }


}