org.springframework.web.servlet.view.velocity
Class VelocityLayoutView

java.lang.Object
  extended by org.springframework.context.support.ApplicationObjectSupport
      extended by org.springframework.web.context.support.WebApplicationObjectSupport
          extended by org.springframework.web.servlet.view.AbstractView
              extended by org.springframework.web.servlet.view.AbstractUrlBasedView
                  extended by org.springframework.web.servlet.view.AbstractTemplateView
                      extended by org.springframework.web.servlet.view.velocity.VelocityView
                          extended by org.springframework.web.servlet.view.velocity.VelocityToolboxView
                              extended by org.springframework.web.servlet.view.velocity.VelocityLayoutView
All Implemented Interfaces:
BeanNameAware, InitializingBean, ApplicationContextAware, ServletContextAware, View

public class VelocityLayoutView
extends VelocityToolboxView

VelocityLayoutView emulates the functionality offered by Velocity's VelocityLayoutServlet to ease page composition from different templates.

The url property should be set to the content template for the view, and the layout template location should be specified as layoutUrl property. A view can override the configured layout template location by setting the appropriate key (the default is "layout") in the content template.

When the view is rendered, the VelocityContext is first merged with the content template (specified by the url property) and then merged with the layout template to produce the final output.

The layout template can include the screen content through a VelocityContext variable (the default is "screen_content"). At runtime, this variable will contain the rendered content template.

Since:
1.2
Author:
Darren Davison, Juergen Hoeller
See Also:
setLayoutUrl(java.lang.String), setLayoutKey(java.lang.String), setScreenContentKey(java.lang.String)

Field Summary
static java.lang.String DEFAULT_LAYOUT_KEY
          The default layout key.
static java.lang.String DEFAULT_LAYOUT_URL
          The default layout url.
static java.lang.String DEFAULT_SCREEN_CONTENT_KEY
          The default screen content key.
 
Fields inherited from class org.springframework.web.servlet.view.AbstractTemplateView
SPRING_MACRO_REQUEST_CONTEXT_ATTRIBUTE
 
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
VelocityLayoutView()
           
 
Method Summary
protected  void checkTemplate()
          Overrides VelocityView.checkTemplate() to additionally check that both the layout template and the screen content template can be loaded.
protected  void doRender(org.apache.velocity.context.Context context, javax.servlet.http.HttpServletResponse response)
          Overrides the normal rendering process in order to pre-process the Context, merging it with the screen template into a single value (identified by the value of screenContentKey).
 void setLayoutKey(java.lang.String layoutKey)
          Set the context key used to specify an alternate layout to be used instead of the default layout.
 void setLayoutUrl(java.lang.String layoutUrl)
          Set the layout template to use.
 void setScreenContentKey(java.lang.String screenContentKey)
          Set the name of the context key that will hold the content of the screen within the layout template.
 
Methods inherited from class org.springframework.web.servlet.view.velocity.VelocityToolboxView
createVelocityContext, getToolboxConfigLocation, initTool, setToolboxConfigLocation
 
Methods inherited from class org.springframework.web.servlet.view.velocity.VelocityView
autodetectVelocityEngine, createVelocityContext, exposeHelpers, exposeHelpers, exposeHelpers, exposeToolAttributes, getEncoding, getTemplate, getTemplate, getVelocityEngine, initApplicationContext, isCacheTemplate, mergeTemplate, renderMergedTemplateModel, setCacheTemplate, setDateToolAttribute, setEncoding, setNumberToolAttribute, setToolAttributes, setVelocityEngine
 
Methods inherited from class org.springframework.web.servlet.view.AbstractTemplateView
applyContentType, renderMergedOutputModel, setAllowRequestOverride, setAllowSessionOverride, setExposeRequestAttributes, setExposeSessionAttributes, setExposeSpringMacroHelpers
 
Methods inherited from class org.springframework.web.servlet.view.AbstractUrlBasedView
afterPropertiesSet, getUrl, isUrlRequired, setUrl, toString
 
Methods inherited from class org.springframework.web.servlet.view.AbstractView
addStaticAttribute, createRequestContext, createTemporaryOutputStream, exposeModelAsRequestAttributes, generatesDownloadContent, getAttributesMap, getBeanName, getContentType, getRequestContextAttribute, getStaticAttributes, prepareResponse, render, setAttributes, setAttributesCSV, setAttributesMap, setBeanName, setContentType, setRequestContextAttribute, writeToResponse
 
Methods inherited from class org.springframework.web.context.support.WebApplicationObjectSupport
getServletContext, getTempDir, getWebApplicationContext, initApplicationContext, initServletContext, 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

DEFAULT_LAYOUT_URL

public static final java.lang.String DEFAULT_LAYOUT_URL
The default layout url.

See Also:
Constant Field Values

DEFAULT_LAYOUT_KEY

public static final java.lang.String DEFAULT_LAYOUT_KEY
The default layout key.

See Also:
Constant Field Values

DEFAULT_SCREEN_CONTENT_KEY

public static final java.lang.String DEFAULT_SCREEN_CONTENT_KEY
The default screen content key.

See Also:
Constant Field Values
Constructor Detail

VelocityLayoutView

public VelocityLayoutView()
Method Detail

setLayoutUrl

public void setLayoutUrl(java.lang.String layoutUrl)
Set the layout template to use. Default is "layout.vm".

Parameters:
layoutUrl - the template location (relative to the template root directory)

setLayoutKey

public void setLayoutKey(java.lang.String layoutKey)
Set the context key used to specify an alternate layout to be used instead of the default layout. Screen content templates can override the layout template that they wish to be wrapped with by setting this value in the template, for example:
#set( $layout = "MyLayout.vm" )

Default key is "layout", as illustrated above.

Parameters:
layoutKey - the name of the key you wish to use in your screen content templates to override the layout template

setScreenContentKey

public void setScreenContentKey(java.lang.String screenContentKey)
Set the name of the context key that will hold the content of the screen within the layout template. This key must be present in the layout template for the current screen to be rendered.

Default is "screen_content": accessed in VTL as $screen_content.

Parameters:
screenContentKey - the name of the screen content key to use

checkTemplate

protected void checkTemplate()
                      throws ApplicationContextException
Overrides VelocityView.checkTemplate() to additionally check that both the layout template and the screen content template can be loaded. Note that during rendering of the screen content, the layout template can be changed which may invalidate any early checking done here.

Overrides:
checkTemplate in class VelocityView
Throws:
ApplicationContextException - if the template cannot be found or is invalid

doRender

protected void doRender(org.apache.velocity.context.Context context,
                        javax.servlet.http.HttpServletResponse response)
                 throws java.lang.Exception
Overrides the normal rendering process in order to pre-process the Context, merging it with the screen template into a single value (identified by the value of screenContentKey). The layout template is then merged with the modified Context in the super class.

Overrides:
doRender in class VelocityView
Parameters:
context - the Velocity context to use for rendering
response - servlet response (use this to get the OutputStream or Writer)
Throws:
java.lang.Exception - if thrown by Velocity
See Also:
AbstractUrlBasedView.setUrl(java.lang.String), VelocityView.getTemplate(), VelocityView.mergeTemplate(org.apache.velocity.Template, org.apache.velocity.context.Context, javax.servlet.http.HttpServletResponse)