org.springframework.web.servlet.view.xslt
Class AbstractXsltView

java.lang.Object
  org.springframework.context.support.ApplicationObjectSupport
      org.springframework.web.context.support.WebApplicationObjectSupport
          org.springframework.web.servlet.view.AbstractView
              org.springframework.web.servlet.view.xslt.AbstractXsltView

All Implemented Interfaces:

BeanNameAware, ApplicationContextAware, ServletContextAware, View

public abstract class AbstractXsltView
extends AbstractView

Convenient superclass for views rendered using an XSLT stylesheet.

Subclasses typically must provide the Source to transform by overriding createXsltSource(java.util.Map, java.lang.String, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse). Subclasses do not need to concern themselves with XSLT other than providing a valid stylesheet location.

Properties:

• stylesheetLocation: a Resource pointing to the XSLT stylesheet
• root: the name of the root element; defaults to "DocRoot"
• uriResolver: the URIResolver to be used in the transform
• errorListener (optional): the ErrorListener implementation instance for custom handling of warnings and errors during TransformerFactory operations
• indent (optional): whether additional whitespace may be added when outputting the result; defaults to true
• cache (optional): are templates to be cached; debug setting only; defaults to true

Note that setting "cache" to false will cause the template objects to be reloaded for each rendering. This is useful during development, but will seriously affect performance in production and is not thread-safe.

Author:

Rod Johnson, Juergen Hoeller, Darren Davison

Field Summary

static String	DEFAULT_ROOT The default document root name
static String	XML_CONTENT_TYPE The default content type if no stylesheet specified

Fields inherited from class org.springframework.web.servlet.view.AbstractView

DEFAULT_CONTENT_TYPE

Fields inherited from class org.springframework.context.support.ApplicationObjectSupport

logger

Constructor Summary

protected

AbstractXsltView() This constructor sets the content type to "text/xml;charset=ISO-8859-1" by default.

Method Summary

protected void	applyTransformerParameters(Map parameters, Transformer transformer) Apply the specified parameters to the given Transformer.
protected Transformer	buildTransformer(Map parameters) Build a Transformer object for immediate use, based on the given parameters.
protected Source	createXsltSource(Map model, String root, HttpServletRequest request, HttpServletResponse response) Return the XML Source to transform.
protected void	doTransform(Map model, Source source, HttpServletRequest request, HttpServletResponse response) Perform the actual transformation, writing to the HTTP response.
protected void	doTransform(Source source, Map parameters, Result result, String encoding) Perform the actual transformation, writing to the given result.
protected Map	getParameters() Deprecated. as of Spring 2.0.4, in favor of the getParameters(HttpServletRequest) variant
protected Map	getParameters(HttpServletRequest request) Return a Map of transformer parameters to be applied to the stylesheet.
protected Map	getParameters(Map model, HttpServletRequest request) Return a Map of transformer parameters to be applied to the stylesheet.
protected Resource	getStylesheetLocation() Return the location of the XSLT stylesheet, if any.
protected Source	getStylesheetSource(Resource stylesheetLocation) Load the stylesheet from the specified location.
protected Templates	getTemplates() Obtain the Templates object to use, based on the configured stylesheet, either a cached one or a freshly built one.
protected TransformerFactory	getTransformerFactory() Return the TransformerFactory used by this view.
protected void	initApplicationContext() Here we load our template, as we need the ApplicationContext to do it.
protected TransformerFactory	newTransformerFactory(Class transformerFactoryClass) Instantiate a new TransformerFactory for this view.
protected void	renderMergedOutputModel(Map model, HttpServletRequest request, HttpServletResponse response) Subclasses must implement this method to actually render the view.
void	resetCachedTemplates() Reset the cached Templates object, if any.
void	setCache(boolean cache) Set whether to activate the template cache for this view.
void	setContentType(String contentType) Set the content type for this view.
void	setErrorListener(ErrorListener errorListener) Set an implementation of the ErrorListener interface for custom handling of transformation errors and warnings.
void	setIndent(boolean indent) Set whether the XSLT transformer may add additional whitespace when outputting the result tree.
void	setOutputProperties(Properties outputProperties) Set arbitrary transformer output properties to be applied to the stylesheet.
void	setRoot(String root) The document root element name.
void	setStylesheetLocation(Resource stylesheetLocation) Set the location of the XSLT stylesheet.
void	setTransformerFactoryClass(Class transformerFactoryClass) Specify the XSLT TransformerFactory class to use.
void	setUriResolver(URIResolver uriResolver) Set the URIResolver used in the transform.
void	setUseSingleModelNameAsRoot(boolean useSingleModelNameAsRoot) Set whether to use the name of a given single model object as the document root element name.
protected boolean	useWriter() Return whether to use a java.io.Writer to write text content to the HTTP response.

Methods inherited from class org.springframework.web.servlet.view.AbstractView

addStaticAttribute, createRequestContext, exposeModelAsRequestAttributes, getAttributesMap, getBeanName, getContentType, getRequestContextAttribute, getStaticAttributes, render, setAttributes, setAttributesCSV, setAttributesMap, setBeanName, setRequestContextAttribute, toString

Methods inherited from class org.springframework.web.context.support.WebApplicationObjectSupport

getServletContext, getTempDir, getWebApplicationContext, isContextRequired, setServletContext

Methods inherited from class org.springframework.context.support.ApplicationObjectSupport

getApplicationContext, getMessageSourceAccessor, requiredContextClass, setApplicationContext

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

XML_CONTENT_TYPE

public static final String XML_CONTENT_TYPE

The default content type if no stylesheet specified

See Also:

Constant Field Values

DEFAULT_ROOT

public static final String DEFAULT_ROOT

The default document root name

See Also:

Constant Field Values

Constructor Detail

AbstractXsltView

protected AbstractXsltView()

This constructor sets the content type to "text/xml;charset=ISO-8859-1" by default. This will be switched to the standard web view default "text/html;charset=ISO-8859-1" if a stylesheet location has been specified.

A specific content type can be configured via the "contentType" bean property.

Method Detail

setContentType

public void setContentType(String contentType)

Description copied from class: AbstractView

Set the content type for this view. Default is "text/html;charset=ISO-8859-1".

May be ignored by subclasses if the view itself is assumed to set the content type, e.g. in case of JSPs.

Overrides:

setContentType in class AbstractView

setTransformerFactoryClass

public void setTransformerFactoryClass(Class transformerFactoryClass)

Specify the XSLT TransformerFactory class to use.

The default constructor of the specified class will be called to build the TransformerFactory for this view.

setStylesheetLocation

public void setStylesheetLocation(Resource stylesheetLocation)

Set the location of the XSLT stylesheet.

If the TransformerFactory used by this instance has already been initialized then invoking this setter will result in the attendant templates being re-cached.

Parameters:

stylesheetLocation - the location of the XSLT stylesheet

See Also:

ResourceLoader.getResource(java.lang.String)

getStylesheetLocation

protected Resource getStylesheetLocation()

Return the location of the XSLT stylesheet, if any.

setRoot

public void setRoot(String root)

The document root element name. Default is "DocRoot".

Only used if we're not passed a single Node as the model.

Parameters:

root - the document root element name

See Also:

DEFAULT_ROOT

setUseSingleModelNameAsRoot

public void setUseSingleModelNameAsRoot(boolean useSingleModelNameAsRoot)

Set whether to use the name of a given single model object as the document root element name.

Default is true : If you pass in a model with a single object named "myElement", then the document root will be named "myElement" as well. Set this flag to false if you want to pass in a single model object while still using the root element name configured through the "root" property.

Parameters:

useSingleModelNameAsRoot - true if the name of a given single model object is to be used as the document root element name

See Also:

setRoot(java.lang.String)

setUriResolver

public void setUriResolver(URIResolver uriResolver)

Set the URIResolver used in the transform.

The URIResolver handles calls to the XSLT document() function.

setErrorListener

public void setErrorListener(ErrorListener errorListener)

Set an implementation of the ErrorListener interface for custom handling of transformation errors and warnings.

If not set, a default SimpleTransformErrorListener is used that simply logs warnings using the logger instance of the view class, and rethrows errors to discontinue the XML transformation.

See Also:

SimpleTransformErrorListener

setIndent

public void setIndent(boolean indent)

Set whether the XSLT transformer may add additional whitespace when outputting the result tree.

Default is true (on); set this to false (off) to not specify an "indent" key, leaving the choice up to the stylesheet.

See Also:

OutputKeys.INDENT

setOutputProperties

public void setOutputProperties(Properties outputProperties)

Set arbitrary transformer output properties to be applied to the stylesheet.

Any values specified here will override defaults that this view sets programmatically.

See Also:

Transformer.setOutputProperty(java.lang.String, java.lang.String)

setCache

public void setCache(boolean cache)

Set whether to activate the template cache for this view.

Default is true. Turn this off to refresh the Templates object on every access, e.g. during development.

See Also:

resetCachedTemplates()

resetCachedTemplates

public final void resetCachedTemplates()

Reset the cached Templates object, if any.

The Templates object will subsequently be rebuilt on next access, if caching is enabled.

See Also:

setCache(boolean)

initApplicationContext

protected final void initApplicationContext()
                                     throws ApplicationContextException

Here we load our template, as we need the ApplicationContext to do it.

Overrides:

initApplicationContext in class ApplicationObjectSupport

Throws:

ApplicationContextException - in case of initialization errors

See Also:

ApplicationObjectSupport.setApplicationContext(org.springframework.context.ApplicationContext)

newTransformerFactory

protected TransformerFactory newTransformerFactory(Class transformerFactoryClass)

Instantiate a new TransformerFactory for this view.

The default implementation simply calls TransformerFactory.newInstance(). If a "transformerFactoryClass" has been specified explicitly, the default constructor of the specified class will be called instead.

Can be overridden in subclasses.

Parameters:

transformerFactoryClass - the specified factory class (if any)

Returns:

the new TransactionFactory instance

Throws:

TransformerFactoryConfigurationError - in case of instantiation failure

See Also:

setTransformerFactoryClass(java.lang.Class), getTransformerFactory()

getTransformerFactory

protected final TransformerFactory getTransformerFactory()

Return the TransformerFactory used by this view. Available once the View object has been fully initialized.

renderMergedOutputModel

protected final void renderMergedOutputModel(Map model,
                                             HttpServletRequest request,
                                             HttpServletResponse response)
                                      throws Exception

Description copied from class: AbstractView

Subclasses must implement this method to actually render the view.

The first step will be preparing the request: In the JSP case, this would mean setting model objects as request attributes. The second step will be the actual rendering of the view, for example including the JSP via a RequestDispatcher.

Specified by:

renderMergedOutputModel in class AbstractView

Parameters:

model - combined output Map (never null), with dynamic values taking precedence over static attributes

request - current HTTP request

response - current HTTP response

Throws:

Exception - if rendering failed

createXsltSource

protected Source createXsltSource(Map model,
                                  String root,
                                  HttpServletRequest request,
                                  HttpServletResponse response)
                           throws Exception

Return the XML Source to transform.

Parameters:

model - the model Map

root - name for root element. This can be supplied as a bean property to concrete subclasses within the view definition file, but will be overridden in the case of a single object in the model map to be the key for that object. If no root property is specified and multiple model objects exist, a default root tag name will be supplied.

request - HTTP request. Subclasses won't normally use this, as request processing should have been complete. However, we might want to create a RequestContext to expose as part of the model.

response - HTTP response. Subclasses won't normally use this, however there may sometimes be a need to set cookies.

Returns:

the XSLT Source to transform

Throws:

Exception - if an error occurs

doTransform

protected void doTransform(Map model,
                           Source source,
                           HttpServletRequest request,
                           HttpServletResponse response)
                    throws Exception

Perform the actual transformation, writing to the HTTP response.

The default implementation delegates to the doTransform(javax.xml.transform.Source, java.util.Map, javax.xml.transform.Result, String) method, building a StreamResult for the ServletResponse OutputStream or for the ServletResponse Writer (according to useWriter()).

Parameters:

model - the model Map

source - the Source to transform

request - current HTTP request

response - current HTTP response

Throws:

Exception - if an error occurs

See Also:

StreamResult, ServletResponse.getOutputStream(), ServletResponse.getWriter(), useWriter()

getParameters

protected Map getParameters(Map model,
                            HttpServletRequest request)

Return a Map of transformer parameters to be applied to the stylesheet.

Subclasses can override this method in order to apply one or more parameters to the transformation process.

The default implementation delegates to the getParameters(HttpServletRequest) variant.

Parameters:

model - the model Map

request - current HTTP request

Returns:

a Map of parameters to apply to the transformation process

See Also:

getParameters(), Transformer.setParameter(java.lang.String, java.lang.Object)

getParameters

protected Map getParameters(HttpServletRequest request)

Return a Map of transformer parameters to be applied to the stylesheet.

Subclasses can override this method in order to apply one or more parameters to the transformation process.

The default implementation delegates to the simple getParameters() variant.

Parameters:

request - current HTTP request

Returns:

a Map of parameters to apply to the transformation process

See Also:

getParameters(Map, HttpServletRequest), Transformer.setParameter(java.lang.String, java.lang.Object)

getParameters

protected Map getParameters()

Deprecated. as of Spring 2.0.4, in favor of the getParameters(HttpServletRequest) variant

Return a Map of transformer parameters to be applied to the stylesheet.

Returns:

a Map of parameters to apply to the transformation process

useWriter

protected boolean useWriter()

Return whether to use a java.io.Writer to write text content to the HTTP response. Else, a java.io.OutputStream will be used, to write binary content to the response.

The default implementation returns false, indicating a a java.io.OutputStream.

Returns:

whether to use a Writer (true) or an OutputStream (false)

See Also:

ServletResponse.getWriter(), ServletResponse.getOutputStream()

doTransform

protected void doTransform(Source source,
                           Map parameters,
                           Result result,
                           String encoding)
                    throws Exception

Perform the actual transformation, writing to the given result.

Parameters:

source - the Source to transform

parameters - a Map of parameters to be applied to the stylesheet (as determined by getParameters(Map, HttpServletRequest))

result - the result to write to

encoding - the preferred character encoding that the underlying Transformer should use

Throws:

Exception - if an error occurs

buildTransformer

protected Transformer buildTransformer(Map parameters)
                                throws TransformerConfigurationException

Build a Transformer object for immediate use, based on the given parameters.

Parameters:

parameters - a Map of parameters to be applied to the stylesheet (as determined by getParameters(Map, HttpServletRequest))

Returns:

the Transformer object (never null)

Throws:

TransformerConfigurationException - if the Transformer object could not be built

getTemplates

protected Templates getTemplates()
                          throws TransformerConfigurationException

Obtain the Templates object to use, based on the configured stylesheet, either a cached one or a freshly built one.

Subclasses may override this method e.g. in order to refresh the Templates instance, calling resetCachedTemplates() before delegating to this getTemplates() implementation.

Returns:

the Templates object (or null if there is no stylesheet specified)

Throws:

TransformerConfigurationException - if the Templates object could not be built

See Also:

setStylesheetLocation(org.springframework.core.io.Resource), setCache(boolean), resetCachedTemplates()

applyTransformerParameters

protected void applyTransformerParameters(Map parameters,
                                          Transformer transformer)

Apply the specified parameters to the given Transformer.

Parameters:

parameters - the transformer parameters (as determined by getParameters(Map, HttpServletRequest))

transformer - the Transformer to aply the parameters

getStylesheetSource

protected Source getStylesheetSource(Resource stylesheetLocation)
                              throws ApplicationContextException

Load the stylesheet from the specified location.

Parameters:

stylesheetLocation - the stylesheet resource to be loaded

Returns:

the stylesheet source

Throws:

ApplicationContextException - if the stylesheet resource could not be loaded