Interface ITemplateResource
- All Known Implementing Classes:
ClassLoaderTemplateResource
,FileTemplateResource
,StringTemplateResource
,UrlTemplateResource
,WebApplicationTemplateResource
Interface implemented by all Template Resource instances.
Template resources are created and returned by Template Resolvers
(ITemplateResolver
) and represent the real resource
that contains the template contents, but do not necessarily contain these contents themselves.
Most usually, template resources are used to obtain a Reader
on the template contents,
abstracting the real location of those contents.
Note that the existence of a template resource object does not imply the existence of the resource
it represents. In order to check whether a resource really exists or not, the exists()
method
can be called. Some implementations of ITemplateResolver
might
in fact do so, but note that this can result in a loss of performance in some scenarios due to a double
access to a resource that might be remote (an HTTP URL, for example): one access for checking existence,
and another access for creating the Reader
to be returned by reader()
.
Note that implementations of these interface might not be thread-safe.
- Since:
- 3.0.0
- Author:
- Daniel Fernández
- See Also:
-
Method Summary
Modifier and TypeMethodDescriptionboolean
exists()
Determines whether the resource represented by this object really exists or not.Returns the base name of a resource.Returns aString
describing the resource.reader()
Returns aReader
that can be used for consuming the template contents.Creates anotherITemplateResource
, usually of the same implementation class, for a resource living in a location relative to the current object's.
-
Method Details
-
getDescription
String getDescription()Returns a
String
describing the resource.Note this should not be taken for a valid resource name, as depending on the implementation it could be too verbose/descriptive or not unique enough to be used for identification purposes.
- Returns:
- the resource description. Should never return
null
.
-
getBaseName
String getBaseName()Returns the base name of a resource.
The base name is aimed at creating derivative names from the name of the resource, usually from the deepest level of the resource path.
For example, a file resource located at
/home/user/template/main.html
should returnmain
as its base name, so that names likemain.properties
,main.th.xml
or similar can be derived, and afterwards resolved usingrelative(String)
.- Returns:
- the base name, or
null
if it cannot be computed for the specific type of resource.
-
exists
boolean exists()Determines whether the resource represented by this object really exists or not.
Note that, depending on the implementation, this might mean actually access the resource, and such operation could have a cost in performance in some scenarios (e.g. a resource representing a remote URL).
This mechanism will be used by Template Resolvers extending from
AbstractTemplateResolver
for checking real resource existence if theAbstractTemplateResolver.setCheckExistence(boolean)
flag is set totrue
.- Returns:
true
if the resource exists,false
if not.
-
reader
Returns a
Reader
that can be used for consuming the template contents.Most implementations of this interface will require specifying a character encoding during construction, so that this readers are correctly able to decode their underlying input streams.
Note this readers should be closed after being fully consumed, just like any other resources.
- Returns:
- a
Reader
on the template contents. Should never returnnull
. - Throws:
IOException
- if an input/output exception happens or if the resource does not exist (e.g.FileNotFoundException
).
-
relative
Creates another
ITemplateResource
, usually of the same implementation class, for a resource living in a location relative to the current object's.Note some
ITemplateResource
implementations might not support this feature.- Parameters:
relativeLocation
- the location of the resource we want to obtain, relative to the current one. Required.- Returns:
- the relative resource. Should never return
null
.
-