public class GraphicImage extends HtmlGraphicImage
The <o:graphicImage> is a component that extends the standard <h:graphicImage>
with support for referencing an InputStream or byte[] property in the value
attribute, optionally as a data URI.
Set dataURI attribute to true in order to render image in
data URI format.
<o:graphicImage name="icon.png" dataURI="true" /> <!-- JSF resource as data URI -->
<o:graphicImage value="#{bean.icon}" dataURI="true" /> <!-- byte[]/InputStream property as data URI -->
This basically renders the image inline in HTML output immediately during JSF render response phase. This approach is very useful for a "preview" feature of uploaded images and works also in combination with view scoped beans. This approach is however not recommended for "permanent" and/or "large" images as it doesn't offer the browser any opportunity to cache the images for reuse, ~10KB would typically be the max even less so if there are more such images on the same page.
When not rendered as data URI, the InputStream or byte[] property must point to
a stateless @ApplicationScoped bean (both JSF and CDI scopes are supported). The property will
namely be evaluated at the moment the browser requests the image content based on the URL as specified in HTML
<img src>, which is usually a different request than the one which rendered the JSF page.
E.g.
@Named
@RequestScoped
public class Bean {
private List<Image> images; // Image class should NOT have "content" property, or at least it be lazy loaded.
@Inject
private ImageService service;
@PostConstruct
public void init() {
images = service.list();
}
public List<Image> getImages() {
return images;
}
}
@Named
@ApplicationScoped
public class ImageStreamer {
@Inject
private ImageService service;
public byte[] getById(Long id) {
return service.getContent(id);
}
}
<ui:repeat value="#{bean.images}" var="image">
<o:graphicImage value="#{imageStreamer.getById(image.id)}" />
</ui:repeat>
A @RequestScoped and @SessionScoped bean would theoretically work, but this is wrong design
(a servlet is inherently also application scoped and stateless, not without reason). A @ViewScoped
wouldn't work because the image request doesn't share the JSF view state.
In case the property is a method expression taking arguments, each of those arguments will be converted to a string
HTTP request parameter and back to actual objects using the converters registered by class as available via
Application.createConverter(Class). So, most of standard types like Long are already implicitly
supported. In case you need to supply a custom object as argument for some reason, you need to explicitly register
a converter for it yourself via @FacesConverter(forClass).
In case your "image" entity supports it, you can also supply the "last modified" property which will be used in the
ETag and Last-Modified headers and in If-Modified-Since checks, hereby
improving browser caching. The lastModified attribute supports both Date and Long as
timestamp in milliseconds.
<ui:repeat value="#{bean.images}" var="image">
<o:graphicImage value="#{imageStreamer.getById(image.id)}" lastModified="#{image.lastModified}" />
</ui:repeat>
The bean class name and method name will end up in the image source URL. Although this is technically harmless and not tamperable by hackers, you might want to choose a "sensible" class and method name for this purpose.
Like <h:graphicImage>, the value attribute is ignored
when the name attribute is specified (for JSF resources). And, the value attribute of
<o:graphicImage> does not support URLs anymore. For that, just keep using
<h:graphicImage> or even plain <img>.
GraphicResource,
DynamicResource,
GraphicResourceHandler,
DefaultResourceHandlerHtmlGraphicImage.PropertyKeys| Modifier and Type | Field and Description |
|---|---|
static Map<String,String> |
ATTRIBUTE_NAMES |
static String |
COMPONENT_TYPE |
COMPONENT_FAMILYATTRS_WITH_DECLARED_DEFAULT_VALUES, BEANINFO_KEY, bindings, COMPOSITE_COMPONENT_TYPE_KEY, COMPOSITE_FACET_NAME, CURRENT_COMPONENT, CURRENT_COMPOSITE_COMPONENT, FACETS_KEY, HONOR_CURRENT_COMPONENT_ATTRIBUTES_PARAM_NAME, VIEW_LOCATION_KEY| Constructor and Description |
|---|
GraphicImage()
Constructs the GraphicImage component.
|
| Modifier and Type | Method and Description |
|---|---|
void |
encodeBegin(FacesContext context) |
void |
encodeEnd(FacesContext context) |
String |
getAlt()
Returns an empty string as default value instead of
null, so that the attribute is always rendered,
as mandated by HTML5. |
protected String |
getSrc(FacesContext context)
Returns the URL needed for the 'src' attribute.
|
getDefaultEventName, getDir, getEventNames, getHeight, getLang, getLongdesc, getOnclick, getOndblclick, getOnkeydown, getOnkeypress, getOnkeyup, getOnmousedown, getOnmousemove, getOnmouseout, getOnmouseover, getOnmouseup, getRole, getStyle, getStyleClass, getTitle, getUsemap, getWidth, isIsmap, setAlt, setDir, setHeight, setIsmap, setLang, setLongdesc, setOnclick, setOndblclick, setOnkeydown, setOnkeypress, setOnkeyup, setOnmousedown, setOnmousemove, setOnmouseout, setOnmouseover, setOnmouseup, setRole, setStyle, setStyleClass, setTitle, setUsemap, setWidthgetFamily, getUrl, getValue, getValueBinding, getValueExpression, setUrl, setValue, setValueBinding, setValueExpressionaddClientBehavior, addFacesListener, broadcast, clearInitialState, decode, encodeChildren, findComponent, getAttributes, getChildCount, getChildren, getClientBehaviors, getClientId, getFacesContext, getFacesListeners, getFacet, getFacetCount, getFacets, getFacetsAndChildren, getId, getListenersForEventClass, getParent, getPassThroughAttributes, getRenderer, getRendererType, getRendersChildren, invokeOnComponent, isRendered, isTransient, markInitialState, processDecodes, processRestoreState, processSaveState, processUpdates, processValidators, queueEvent, removeFacesListener, restoreAttachedState, restoreState, saveAttachedState, saveState, setId, setParent, setRendered, setRendererType, setTransient, subscribeToEvent, unsubscribeFromEventencodeAll, getClientId, getCompositeComponentParent, getContainerClientId, getCurrentComponent, getCurrentCompositeComponent, getNamingContainer, getPassThroughAttributes, getResourceBundleMap, getStateHelper, getStateHelper, getTransientStateHelper, getTransientStateHelper, initialStateMarked, isCompositeComponent, isInView, isVisitable, popComponentFromEL, processEvent, pushComponentToEL, restoreTransientState, saveTransientState, setInView, visitTreeclone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, waitaddClientBehavior, getClientBehaviorspublic static final String COMPONENT_TYPE
public void encodeBegin(FacesContext context) throws IOException
encodeBegin in class UIComponentBaseIOExceptionpublic void encodeEnd(FacesContext context) throws IOException
encodeEnd in class UIComponentBaseIOExceptionprotected String getSrc(FacesContext context) throws IOException
context - The involved faces context.IOException - When something fails at I/O level.public String getAlt()
null, so that the attribute is always rendered,
as mandated by HTML5.getAlt in class HtmlGraphicImageCopyright © 2012–2014 OmniFaces. All rights reserved.