Package freemarker.cache
Class WebappTemplateLoader
- java.lang.Object
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- freemarker.cache.WebappTemplateLoader
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- All Implemented Interfaces:
TemplateLoader
public class WebappTemplateLoader extends Object implements TemplateLoader
ATemplateLoader
that uses streams reachable throughServletContext.getResource(String)
as its source of templates.
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Constructor Summary
Constructors Constructor Description WebappTemplateLoader(javax.servlet.ServletContext servletContext)
Creates a resource template cache that will use the specified servlet context to load the resources.WebappTemplateLoader(javax.servlet.ServletContext servletContext, String subdirPath)
Creates a template loader that will use the specified servlet context to load the resources.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
closeTemplateSource(Object templateSource)
Closes the template source, releasing any resources held that are only required for reading the template and/or its metadata.Object
findTemplateSource(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 ofsetAttemptFileAccess(boolean)
.long
getLastModified(Object templateSource)
Returns the time of last modification of the specified template source.Reader
getReader(Object templateSource, String encoding)
Returns the character stream of a template represented by the specified template source.Boolean
getURLConnectionUsesCaches()
Getter pair ofsetURLConnectionUsesCaches(Boolean)
.void
setAttemptFileAccess(boolean attemptLoadingFromFile)
Specifies that before loading templates withServletContext.getResource(String)
, it should try to load the template asFile
; default istrue
, though it's not always recommended anymore.void
setURLConnectionUsesCaches(Boolean urlConnectionUsesCaches)
It does the same asURLTemplateLoader.setURLConnectionUsesCaches(Boolean)
; see there.String
toString()
Show class name and some details that are useful in template-not-found errors.
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Constructor Detail
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WebappTemplateLoader
public WebappTemplateLoader(javax.servlet.ServletContext servletContext)
Creates a resource template cache that will use the specified servlet context to load the resources. It will use the base path of"/"
meaning templates will be resolved relative to the servlet context root location.- Parameters:
servletContext
- the servlet context whoseServletContext.getResource(String)
will be used to load the templates.
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WebappTemplateLoader
public WebappTemplateLoader(javax.servlet.ServletContext servletContext, String subdirPath)
Creates a template loader that will use the specified servlet context to load the resources. It will use the specified base path, which is interpreted relatively to the context root (does not mater if you start it with "/" or not). Path components should be separated by forward slashes independently of the separator character used by the underlying operating system.- Parameters:
servletContext
- the servlet context whoseServletContext.getResource(String)
will be used to load the templates.subdirPath
- the base path to template resources.
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Method Detail
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findTemplateSource
public Object findTemplateSource(String name) throws IOException
Description copied from interface:TemplateLoader
Finds the template in the backing storage and returns an object that identifies the storage location where the template can be loaded from. See the return value for more information.- Specified by:
findTemplateSource
in interfaceTemplateLoader
- Parameters:
name
- The name of the template, already localized and normalized by thecache
. 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, 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 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.- Returns:
- An object representing the template source, which can be supplied in subsequent calls to
TemplateLoader.getLastModified(Object)
andTemplateLoader.getReader(Object, String)
, when those are called on the sameTemplateLoader
.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 theTemplateLoader
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 properObject.equals(Object)
andObject.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 fromObject.equals(Object)
when the compared template sources came from the sameTemplateLoader
instance. Also, it must not influence the equality if the source is open or closed (TemplateLoader.closeTemplateSource(Object)
). - Throws:
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 withnull
then!
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getLastModified
public long getLastModified(Object templateSource)
Description copied from interface:TemplateLoader
Returns the time of last modification of the specified template source. This method is called afterfindTemplateSource()
.- Specified by:
getLastModified
in interfaceTemplateLoader
- Parameters:
templateSource
- an object representing a template source, obtained through a prior call toTemplateLoader.findTemplateSource(String)
. This must be an object on whichTemplateLoader.closeTemplateSource(Object)
wasn't applied yet.- Returns:
- the time of last modification of the specified template source, or -1 if the time is not known.
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getReader
public Reader getReader(Object templateSource, String encoding) throws IOException
Description copied from interface:TemplateLoader
Returns the character stream of a template represented by the specified template source. This method is possibly called for multiple times for the same template source object, and it must always return aReader
that reads the template from its beginning. Before this method is called for the second time (or later), its caller must close the previously returnedReader
, and it must not use it anymore. That is, this method is not required to support multiple concurrent readers for the same sourcetemplateSource
object.Typically, this method is called if the template is missing from the cache, or if after calling
TemplateLoader.findTemplateSource(String)
andTemplateLoader.getLastModified(Object)
it was determined that the cached copy of the template is stale. Then, if it turns out that theencoding
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 correctencoding
parameter value.- Specified by:
getReader
in interfaceTemplateLoader
- Parameters:
templateSource
- an object representing a template source, obtained through a prior call toTemplateLoader.findTemplateSource(String)
. This must be an object on whichTemplateLoader.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.- Returns:
- A
Reader
representing the template character stream. It's the responsibility of the caller (which isTemplateCache
usually) toclose()
it. TheReader
is not required to work after thetemplateSource
was closed (TemplateLoader.closeTemplateSource(Object)
). - Throws:
IOException
- if an I/O error occurs while accessing the stream.
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closeTemplateSource
public void closeTemplateSource(Object templateSource) throws IOException
Description copied from interface:TemplateLoader
Closes the template source, releasing any resources held that are only required for reading the template and/or its metadata. This is the last method that is called by theTemplateCache
for a template source, except thatObject.equals(Object)
is might called later too.TemplateCache
ensures that this method will be called on every object that is returned fromTemplateLoader.findTemplateSource(String)
.- Specified by:
closeTemplateSource
in interfaceTemplateLoader
- Parameters:
templateSource
- the template source that should be closed.- Throws:
IOException
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getURLConnectionUsesCaches
public Boolean getURLConnectionUsesCaches()
Getter pair ofsetURLConnectionUsesCaches(Boolean)
.- Since:
- 2.3.21
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setURLConnectionUsesCaches
public void setURLConnectionUsesCaches(Boolean urlConnectionUsesCaches)
It does the same asURLTemplateLoader.setURLConnectionUsesCaches(Boolean)
; see there.- Since:
- 2.3.21
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toString
public String toString()
Show class name and some details that are useful in template-not-found errors.
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getAttemptFileAccess
public boolean getAttemptFileAccess()
Getter pair ofsetAttemptFileAccess(boolean)
.- Since:
- 2.3.23
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setAttemptFileAccess
public void setAttemptFileAccess(boolean attemptLoadingFromFile)
Specifies that before loading templates withServletContext.getResource(String)
, it should try to load the template asFile
; default istrue
, 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 withsetURLConnectionUsesCaches(Boolean)
, which is also the default behavior withincompatible_improvements
2.3.21 and later.- Since:
- 2.3.23
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