org.springframework.web.servlet.view

Class AbstractView

java.lang.Object

org.springframework.context.support.ApplicationObjectSupport

org.springframework.web.context.support.WebApplicationObjectSupport

org.springframework.web.servlet.view.AbstractView

All Implemented Interfaces:

Aware, BeanNameAware, ApplicationContextAware, ServletContextAware, View

Direct Known Subclasses:

AbstractExcelView, AbstractFeedView, AbstractJackson2View, AbstractJExcelView, AbstractPdfView, AbstractUrlBasedView, MarshallingView

public abstract class AbstractView
extends WebApplicationObjectSupport
implements View, BeanNameAware

Abstract base class for View implementations. Subclasses should be JavaBeans, to allow for convenient configuration as Spring-managed bean instances.

Provides support for static attributes, to be made available to the view, with a variety of ways to specify them. Static attributes will be merged with the given dynamic attributes (the model that the controller returned) for each render operation.

Extends WebApplicationObjectSupport, which will be helpful to some views. Subclasses just need to implement the actual rendering.

Author:

Rod Johnson, Juergen Hoeller

See Also:

setAttributes(java.util.Properties), setAttributesMap(java.util.Map<java.lang.String, ?>), renderMergedOutputModel(java.util.Map<java.lang.String, java.lang.Object>, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)

Field Summary

Fields

Modifier and Type	Field and Description
static String	DEFAULT_CONTENT_TYPE 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, SELECTED_CONTENT_TYPE

Constructor Summary

Constructors

Constructor and Description
AbstractView()

Method Summary

Modifier and Type	Method and Description
void	addStaticAttribute(String name, Object value) Add static data to this view, exposed in each view.
protected Map<String,Object>	createMergedOutputModel(Map<String,?> model, HttpServletRequest request, HttpServletResponse response) Creates a combined output Map (never null) that includes dynamic values and static attributes.
protected RequestContext	createRequestContext(HttpServletRequest request, HttpServletResponse response, Map<String,Object> model) Create a RequestContext to expose under the specified attribute name.
protected ByteArrayOutputStream	createTemporaryOutputStream() Create a temporary OutputStream for this view.
protected void	exposeModelAsRequestAttributes(Map<String,Object> model, HttpServletRequest request) Expose the model objects in the given map as request attributes.
protected boolean	generatesDownloadContent() Return whether this view generates download content (typically binary content like PDF or Excel files).
Map<String,Object>	getAttributesMap() Allow Map access to the static attributes of this view, with the option to add or override specific entries.
String	getBeanName() Return the view's name.
String	getContentType() Return the content type for this view.
String	getRequestContextAttribute() Return the name of the RequestContext attribute, if any.
protected HttpServletRequest	getRequestToExpose(HttpServletRequest originalRequest) Get the request handle to expose to renderMergedOutputModel(java.util.Map<java.lang.String, java.lang.Object>, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse), i.e.
Map<String,Object>	getStaticAttributes() Return the static attributes for this view.
boolean	isExposePathVariables() Return whether to add path variables to the model or not.
protected void	prepareResponse(HttpServletRequest request, HttpServletResponse response) Prepare the given response for rendering.
void	render(Map<String,?> model, HttpServletRequest request, HttpServletResponse response) Prepares the view given the specified model, merging it with static attributes and a RequestContext attribute, if necessary.
protected abstract void	renderMergedOutputModel(Map<String,Object> model, HttpServletRequest request, HttpServletResponse response) Subclasses must implement this method to actually render the view.
void	setAttributes(Properties attributes) Set static attributes for this view from a java.util.Properties object.
void	setAttributesCSV(String propString) Set static attributes as a CSV string.
void	setAttributesMap(Map<String,?> attributes) Set static attributes for this view from a Map.
void	setBeanName(String beanName) Set the view's name.
void	setContentType(String contentType) Set the content type for this view.
void	setExposeContextBeansAsAttributes(boolean exposeContextBeansAsAttributes) Set whether to make all Spring beans in the application context accessible as request attributes, through lazy checking once an attribute gets accessed.
void	setExposedContextBeanNames(String... exposedContextBeanNames) Specify the names of beans in the context which are supposed to be exposed.
void	setExposePathVariables(boolean exposePathVariables) Specify whether to add path variables to the model or not.
void	setRequestContextAttribute(String requestContextAttribute) Set the name of the RequestContext attribute for this view.
protected void	setResponseContentType(HttpServletRequest request, HttpServletResponse response) Set the content type of the response to the configured content type unless the View.SELECTED_CONTENT_TYPE request attribute is present and set to a concrete media type.
String	toString()
protected void	writeToResponse(HttpServletResponse response, ByteArrayOutputStream baos) Write the given temporary OutputStream to the HTTP response.

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, initApplicationContext, requiredContextClass, setApplicationContext

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_CONTENT_TYPE

public static final String DEFAULT_CONTENT_TYPE

Default content type. Overridable as bean property.

See Also:

Constant Field Values

Constructor Detail

AbstractView

public AbstractView()

Method Detail

setBeanName

public void setBeanName(String beanName)

Set the view's name. Helpful for traceability.

Framework code must call this when constructing views.

Specified by:

setBeanName in interface BeanNameAware

Parameters:

beanName - the name of the bean in the factory. Note that this name is the actual bean name used in the factory, which may differ from the originally specified name: in particular for inner bean names, the actual bean name might have been made unique through appending "#..." suffixes. Use the BeanFactoryUtils.originalBeanName(String) method to extract the original bean name (without suffix), if desired.

getBeanName

public String getBeanName()

Return the view's name. Should never be null, if the view was correctly configured.

setContentType

public void setContentType(String contentType)

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.

getContentType

public String getContentType()

Return the content type for this view.

Specified by:

getContentType in interface View

Returns:

the content type String (optionally including a character set), or null if not predetermined.

setRequestContextAttribute

public void setRequestContextAttribute(String requestContextAttribute)

Set the name of the RequestContext attribute for this view. Default is none.

getRequestContextAttribute

public String getRequestContextAttribute()

Return the name of the RequestContext attribute, if any.

setAttributesCSV

public void setAttributesCSV(String propString)
                      throws IllegalArgumentException

Set static attributes as a CSV string. Format is: attname0={value1},attname1={value1}

"Static" attributes are fixed attributes that are specified in the View instance configuration. "Dynamic" attributes, on the other hand, are values passed in as part of the model.

Throws:

IllegalArgumentException

setAttributes

public void setAttributes(Properties attributes)

Set static attributes for this view from a java.util.Properties object.

"Static" attributes are fixed attributes that are specified in the View instance configuration. "Dynamic" attributes, on the other hand, are values passed in as part of the model.

This is the most convenient way to set static attributes. Note that static attributes can be overridden by dynamic attributes, if a value with the same name is included in the model.

Can be populated with a String "value" (parsed via PropertiesEditor) or a "props" element in XML bean definitions.

See Also:

PropertiesEditor

setAttributesMap

public void setAttributesMap(Map<String,?> attributes)

Set static attributes for this view from a Map. This allows to set any kind of attribute values, for example bean references.

"Static" attributes are fixed attributes that are specified in the View instance configuration. "Dynamic" attributes, on the other hand, are values passed in as part of the model.

Can be populated with a "map" or "props" element in XML bean definitions.

Parameters:

attributes - Map with name Strings as keys and attribute objects as values

getAttributesMap

public Map<String,Object> getAttributesMap()

Allow Map access to the static attributes of this view, with the option to add or override specific entries.

Useful for specifying entries directly, for example via "attributesMap[myKey]". This is particularly useful for adding or overriding entries in child view definitions.

addStaticAttribute

public void addStaticAttribute(String name,
                               Object value)

Add static data to this view, exposed in each view.

"Static" attributes are fixed attributes that are specified in the View instance configuration. "Dynamic" attributes, on the other hand, are values passed in as part of the model.

Must be invoked before any calls to render.

Parameters:

name - the name of the attribute to expose

value - the attribute value to expose

See Also:

render(java.util.Map<java.lang.String, ?>, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)

getStaticAttributes

public Map<String,Object> getStaticAttributes()

Return the static attributes for this view. Handy for testing.

Returns an unmodifiable Map, as this is not intended for manipulating the Map but rather just for checking the contents.

Returns:

the static attributes in this view

setExposePathVariables

public void setExposePathVariables(boolean exposePathVariables)

Specify whether to add path variables to the model or not.

Path variables are commonly bound to URI template variables through the @PathVariable annotation. They're are effectively URI template variables with type conversion applied to them to derive typed Object values. Such values are frequently needed in views for constructing links to the same and other URLs.

Path variables added to the model override static attributes (see setAttributes(Properties)) but not attributes already present in the model.

By default this flag is set to true. Concrete view types can override this.

Parameters:

exposePathVariables - true to expose path variables, and false otherwise

isExposePathVariables

public boolean isExposePathVariables()

Return whether to add path variables to the model or not.

setExposeContextBeansAsAttributes

public void setExposeContextBeansAsAttributes(boolean exposeContextBeansAsAttributes)

Set whether to make all Spring beans in the application context accessible as request attributes, through lazy checking once an attribute gets accessed.

This will make all such beans accessible in plain ${...} expressions in a JSP 2.0 page, as well as in JSTL's c:out value expressions.

Default is "false". Switch this flag on to transparently expose all Spring beans in the request attribute namespace.

NOTE: Context beans will override any custom request or session attributes of the same name that have been manually added. However, model attributes (as explicitly exposed to this view) of the same name will always override context beans.

See Also:

getRequestToExpose(javax.servlet.http.HttpServletRequest)

setExposedContextBeanNames

public void setExposedContextBeanNames(String... exposedContextBeanNames)

Specify the names of beans in the context which are supposed to be exposed. If this is non-null, only the specified beans are eligible for exposure as attributes.

If you'd like to expose all Spring beans in the application context, switch the "exposeContextBeansAsAttributes" flag on but do not list specific bean names for this property.

render

public void render(Map<String,?> model,
                   HttpServletRequest request,
                   HttpServletResponse response)
            throws Exception

Prepares the view given the specified model, merging it with static attributes and a RequestContext attribute, if necessary. Delegates to renderMergedOutputModel for the actual rendering.

Specified by:

render in interface View

Parameters:

model - Map with name Strings as keys and corresponding model objects as values (Map can also be null in case of empty model)

request - current HTTP request

response - HTTP response we are building

Throws:

Exception - if rendering failed

See Also:

renderMergedOutputModel(java.util.Map<java.lang.String, java.lang.Object>, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)

createMergedOutputModel

protected Map<String,Object> createMergedOutputModel(Map<String,?> model,
                                                     HttpServletRequest request,
                                                     HttpServletResponse response)

Creates a combined output Map (never null) that includes dynamic values and static attributes. Dynamic values take precedence over static attributes.

createRequestContext

protected RequestContext createRequestContext(HttpServletRequest request,
                                              HttpServletResponse response,
                                              Map<String,Object> model)

Create a RequestContext to expose under the specified attribute name.

Default implementation creates a standard RequestContext instance for the given request and model. Can be overridden in subclasses for custom instances.

Parameters:

request - current HTTP request

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

Returns:

the RequestContext instance

See Also:

setRequestContextAttribute(java.lang.String), RequestContext

prepareResponse

protected void prepareResponse(HttpServletRequest request,
                               HttpServletResponse response)

Prepare the given response for rendering.

The default implementation applies a workaround for an IE bug when sending download content via HTTPS.

Parameters:

request - current HTTP request

response - current HTTP response

generatesDownloadContent

protected boolean generatesDownloadContent()

Return whether this view generates download content (typically binary content like PDF or Excel files).

The default implementation returns false. Subclasses are encouraged to return true here if they know that they are generating download content that requires temporary caching on the client side, typically via the response OutputStream.

See Also:

prepareResponse(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse), ServletResponse.getOutputStream()

getRequestToExpose

protected HttpServletRequest getRequestToExpose(HttpServletRequest originalRequest)

Get the request handle to expose to renderMergedOutputModel(java.util.Map<java.lang.String, java.lang.Object>, javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse), i.e. to the view.

The default implementation wraps the original request for exposure of Spring beans as request attributes (if demanded).

Parameters:

originalRequest - the original servlet request as provided by the engine

Returns:

the wrapped request, or the original request if no wrapping is necessary

See Also:

setExposeContextBeansAsAttributes(boolean), setExposedContextBeanNames(java.lang.String...), ContextExposingHttpServletRequest

renderMergedOutputModel

protected abstract void renderMergedOutputModel(Map<String,Object> model,
                                                HttpServletRequest request,
                                                HttpServletResponse response)
                                         throws Exception

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.

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

exposeModelAsRequestAttributes

protected void exposeModelAsRequestAttributes(Map<String,Object> model,
                                              HttpServletRequest request)
                                       throws Exception

Expose the model objects in the given map as request attributes. Names will be taken from the model Map. This method is suitable for all resources reachable by RequestDispatcher.

Parameters:

model - Map of model objects to expose

request - current HTTP request

Throws:

Exception

createTemporaryOutputStream

protected ByteArrayOutputStream createTemporaryOutputStream()

Create a temporary OutputStream for this view.

This is typically used as IE workaround, for setting the content length header from the temporary stream before actually writing the content to the HTTP response.

writeToResponse

protected void writeToResponse(HttpServletResponse response,
                               ByteArrayOutputStream baos)
                        throws IOException

Write the given temporary OutputStream to the HTTP response.

Parameters:

response - current HTTP response

baos - the temporary OutputStream to write

Throws:

IOException - if writing/flushing failed

setResponseContentType

protected void setResponseContentType(HttpServletRequest request,
                                      HttpServletResponse response)

Set the content type of the response to the configured content type unless the View.SELECTED_CONTENT_TYPE request attribute is present and set to a concrete media type.

toString

public String toString()

Overrides:

toString in class Object