public class WebappTemplateLoader extends java.lang.Object implements TemplateLoader
TemplateLoader
that uses streams reachable through ServletContext.getResource(String)
as its source
of templates.Constructor and Description |
---|
WebappTemplateLoader(javax.servlet.ServletContext servletContext)
Creates a template loader that will use the specified servlet context to load the resources.
|
WebappTemplateLoader(javax.servlet.ServletContext servletContext,
java.lang.String subdirPath)
Creates a template loader that will use the specified servlet context to load the resources.
|
Modifier and Type | Method and Description |
---|---|
void |
closeTemplateSource(java.lang.Object templateSource)
Closes the template source, releasing any resources held that are only required for reading the template and/or
its metadata.
|
java.lang.Object |
findTemplateSource(java.lang.String name)
Finds the template in the backing storage and returns an object that identifies the storage location where the
template can be loaded from.
|
boolean |
getAttemptFileAccess()
Getter pair of
setAttemptFileAccess(boolean) . |
long |
getLastModified(java.lang.Object templateSource)
Returns the time of last modification of the specified template source.
|
java.io.Reader |
getReader(java.lang.Object templateSource,
java.lang.String encoding)
Returns the character stream of a template represented by the specified template source.
|
java.lang.Boolean |
getURLConnectionUsesCaches()
Getter pair of
setURLConnectionUsesCaches(Boolean) . |
void |
setAttemptFileAccess(boolean attemptLoadingFromFile)
Specifies that before loading templates with
ServletContext.getResource(String) , it should try to load
the template as File ; default is true , though it's not always recommended anymore. |
void |
setURLConnectionUsesCaches(java.lang.Boolean urlConnectionUsesCaches)
It does the same as
URLTemplateLoader.setURLConnectionUsesCaches(Boolean) ; see there. |
java.lang.String |
toString()
Show class name and some details that are useful in template-not-found errors.
|
public WebappTemplateLoader(javax.servlet.ServletContext servletContext)
"/"
meaning templates will be resolved relative to the servlet context root
location.servletContext
- the servlet context whose ServletContext.getResource(String)
will be used to load the
templates.public WebappTemplateLoader(javax.servlet.ServletContext servletContext, java.lang.String subdirPath)
servletContext
- the servlet context whose ServletContext.getResource(String)
will be used to load the
templates.subdirPath
- the base path to template resources.public java.lang.Object findTemplateSource(java.lang.String name) throws java.io.IOException
TemplateLoader
findTemplateSource
in interface TemplateLoader
name
- The name (template root directory relative path) 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's up to the template loader to handle them (say, by throwing an
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 referred as the "template root directory"), 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
normalization will not properly happen, as FreeMarker (the cache) recognizes only the slashes as
separators.TemplateLoader.getLastModified(Object)
and TemplateLoader.getReader(Object, String)
, when those are called on the
same TemplateLoader
. null
must be returned if the source for the template doesn't exist;
don't throw exception then! The exact type of this object is up to the TemplateLoader
implementation. As this object is possibly used as hash key in caches, and is surly compared with another
template source for equality, it must have a proper Object.equals(Object)
and
Object.hashCode()
) implementation. Especially, template sources that refer to the same
physical source must be equivalent, otherwise template caching can become inefficient. This is only
expected from Object.equals(Object)
when the compared template sources came from the same
TemplateLoader
instance. Also, it must not influence the equality if the source is open or
closed (TemplateLoader.closeTemplateSource(Object)
).java.io.IOException
- When an error occurs that makes it impossible to find out if the template exists, or to access the
existing template. Don't throw exception if the template doesn't exist, instead return with
null
then!public long getLastModified(java.lang.Object templateSource)
TemplateLoader
findTemplateSource()
.getLastModified
in interface TemplateLoader
templateSource
- an object representing a template source (the template file), obtained through a prior call to
TemplateLoader.findTemplateSource(String)
. This must be an object on which
TemplateLoader.closeTemplateSource(Object)
wasn't applied yet.Long.MIN_VALUE
is reserved for internal use.public java.io.Reader getReader(java.lang.Object templateSource, java.lang.String encoding) throws java.io.IOException
TemplateLoader
Reader
that
reads the template from its beginning. Before this method is called for the second time (or later), its caller
must close the previously returned Reader
, and it must not use it anymore. That is, this method is not
required to support multiple concurrent readers for the same source templateSource
object.
Typically, this method is called if the template is missing from the cache, or if after calling
TemplateLoader.findTemplateSource(String)
and TemplateLoader.getLastModified(Object)
it was determined that the cached copy
of the template is stale. Then, if it turns out that the encoding
parameter used doesn't match the actual
template content (based on the #ftl encoding=...
header), this method will be called for a second time
with the correct encoding
parameter value.
Unlike TemplateLoader.findTemplateSource(String)
, this method must not tolerate if the template is not found, and
must throw IOException
in that case.
getReader
in interface TemplateLoader
templateSource
- an object representing a template source, obtained through a prior call to
TemplateLoader.findTemplateSource(String)
. This must be an object on which
TemplateLoader.closeTemplateSource(Object)
wasn't applied yet.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 should ignore the encoding parameter.Reader
representing the template character stream; not null
. It's the responsibility of
the caller (which is TemplateCache
usually) to close()
it. The Reader
is not
required to work after the templateSource
was closed (TemplateLoader.closeTemplateSource(Object)
).java.io.IOException
- if an I/O error occurs while accessing the stream.public void closeTemplateSource(java.lang.Object templateSource) throws java.io.IOException
TemplateLoader
TemplateCache
for a template source, except
that Object.equals(Object)
is might called later too. TemplateCache
ensures 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.java.io.IOException
public java.lang.Boolean getURLConnectionUsesCaches()
setURLConnectionUsesCaches(Boolean)
.public void setURLConnectionUsesCaches(java.lang.Boolean urlConnectionUsesCaches)
URLTemplateLoader.setURLConnectionUsesCaches(Boolean)
; see there.public java.lang.String toString()
toString
in class java.lang.Object
public boolean getAttemptFileAccess()
setAttemptFileAccess(boolean)
.public void setAttemptFileAccess(boolean attemptLoadingFromFile)
ServletContext.getResource(String)
, it should try to load
the template as File
; default is true
, though it's not always recommended anymore. This is a
workaround for the case when the servlet container doesn't show template modifications after the template was
already loaded earlier. But it's certainly better to counter this problem by disabling the URL connection cache
with setURLConnectionUsesCaches(Boolean)
, which is also the default behavior with
incompatible_improvements
2.3.21
and later.