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

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.AbstractUrlBasedView
                  org.springframework.web.servlet.view.AbstractTemplateView
                      org.springframework.web.servlet.view.velocity.VelocityView
                          org.springframework.web.servlet.view.velocity.VelocityToolboxView
                              org.springframework.web.servlet.view.velocity.VelocityLayoutView

All Implemented Interfaces:

Aware, 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 String	DEFAULT_LAYOUT_KEY The default layout key.
static String	DEFAULT_LAYOUT_URL The default layout url.
static 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

Fields inherited from interface org.springframework.web.servlet.View

PATH_VARIABLES, RESPONSE_STATUS_ATTRIBUTE

Constructor Summary

VelocityLayoutView()

Method Summary

boolean	checkResource(Locale locale) Overrides VelocityView.checkTemplate() to additionally check that both the layout template and the screen content template can be loaded.
protected void	doRender(Context context, 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(String layoutKey) Set the context key used to specify an alternate layout to be used instead of the default layout.
void	setLayoutUrl(String layoutUrl) Set the layout template to use.
void	setScreenContentKey(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, createMergedOutputModel, createRequestContext, createTemporaryOutputStream, exposeModelAsRequestAttributes, generatesDownloadContent, getAttributesMap, getBeanName, getContentType, getRequestContextAttribute, getStaticAttributes, isExposePathVariables, prepareResponse, render, setAttributes, setAttributesCSV, setAttributesMap, setBeanName, setContentType, setExposePathVariables, 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 String DEFAULT_LAYOUT_URL

The default layout url.

See Also:

Constant Field Values

DEFAULT_LAYOUT_KEY

public static final String DEFAULT_LAYOUT_KEY

The default layout key.

See Also:

Constant Field Values

DEFAULT_SCREEN_CONTENT_KEY

public static final 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(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(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(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

checkResource

public boolean checkResource(Locale locale)
                      throws Exception

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:

checkResource in class VelocityView

Parameters:

locale - the desired Locale that we're looking for

Returns:

true if the resource exists (or is assumed to exist); false if we know that it does not exist

Throws:

Exception - if the resource exists but is invalid (e.g. could not be parsed)

doRender

protected void doRender(Context context,
                        HttpServletResponse response)
                 throws 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:

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)