freemarker.cache
Class URLTemplateLoader
java.lang.Object
freemarker.cache.URLTemplateLoader
- TemplateLoader
public abstract class URLTemplateLoader
extends java.lang.Object
$Id: URLTemplateLoader.java,v 1.14 2003/01/29 08:01:17 szegedia Exp $protected static String | canonicalizePrefix(String prefix) - Can be used by subclasses to canonicalize URL path prefixes.
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void | closeTemplateSource(Object templateSource) - Closes the template source.
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Object | findTemplateSource(String name) - Finds the object that acts as the source of the template with the
given name.
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long | getLastModified(Object templateSource) - Returns the time of last modification of the specified template source.
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Reader | getReader(Object templateSource, String encoding) - Returns the character stream of a template represented by the specified
template source.
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protected abstract URL | getURL(String name) - Given a template name (plus potential locale decorations) retrieves
an URL that points the template source.
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canonicalizePrefix
protected static String canonicalizePrefix(String prefix)
Can be used by subclasses to canonicalize URL path prefixes.
prefix
- the path prefix to canonicalize
- the canonicalized prefix. All backslashes are replaced with
forward slashes, and a trailing slash is appended if the original
prefix wasn't empty and didn't already end with a slash.
closeTemplateSource
public void closeTemplateSource(Object templateSource)
throws IOException
Closes the template source. This is the last method that is called by
the TemplateCache for a templateSource. The framework guarantees that
this method will be called on every object that is returned from
TemplateLoader.findTemplateSource(String)
.
- closeTemplateSource in interface TemplateLoader
templateSource
- the template source that should be closed.
findTemplateSource
public Object findTemplateSource(String name)
throws IOException
- findTemplateSource in interface TemplateLoader
name
- the name of the template, already localized and normalized by
the cache
.
It is completely up to the loader implementation to interpret
the name, however it should expect to receive hierarchical paths where
path components are separated by a slash (not backslash). Backslashes
(or any other OS specific separator character) are not considered as separators by
FreeMarker, and thus they will not be replaced with slash before passing to this method,
so it is up to the template loader to handle them (say, be throwing and exception that
tells the user that the path (s)he has entered is invalid, as (s)he must use slash --
typical mistake of Windows users).
The passed names are always considered relative to some loader-defined root
location (often reffered as the "template root direcotry"), and will never start with
a slash, nor will they contain a path component consisting of either a single or a double
dot -- these are all resolved by the template cache before passing the name to the
loader. As a side effect, paths that trivially reach outside template root directory,
such as ../my.ftl, will be rejected by the template cache, so they never
reach the template loader. Note again, that if the path uses backslash as path separator
instead of slash as (the template loader should not accept that), the normalisation will
not properly happen, as FreeMarker (the cache) recognizes only the slashes as separators.
- an object representing the template source, which can be
supplied in subsequent calls to
TemplateLoader.getLastModified(Object)
and
TemplateLoader.getReader(Object,String)
. Null must be returned if the source
for the template can not be found (do not throw FileNotFoundException
!).
The returned object may will be compared with a cached template source
object for equality, using the equals
method. Thus,
objects returned for the same physical source must be equivalent
according to equals
method, otherwise template caching
can become very ineffective!
getLastModified
public long getLastModified(Object templateSource)
Returns the time of last modification of the specified template source.
This method is called after findTemplateSource()
.
- getLastModified in interface TemplateLoader
- the time of last modification of the specified template source,
or -1 if the time is not known.
getReader
public Reader getReader(Object templateSource,
String encoding)
throws IOException
Returns the character stream of a template represented by the specified
template source. This method is called after getLastModified()
if it is determined that a cached copy of the template is unavailable
or stale.
- getReader in interface TemplateLoader
templateSource
- an object representing a template source, obtained
through a prior call to TemplateLoader.findTemplateSource(String)
.encoding
- the character encoding used to translate source bytes
to characters. Some loaders may not have access to the byte
representation of the template stream, and instead directly obtain a
character stream. These loaders will - quite naturally - ignore the
encoding parameter.
- a reader representing the template character stream. The
framework will call
close()
.
getURL
protected abstract URL getURL(String name)
Given a template name (plus potential locale decorations) retrieves
an URL that points the template source.
name
- the name of the sought template, including the locale
decorations.
- an URL that points to the template source, or null if it can
determine that the template source does not exist.