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/*
* Copyright (c) 1997, 2018 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0, which is available at
* http://www.eclipse.org/legal/epl-2.0.
*
* This Source Code may also be made available under the following Secondary
* Licenses when the conditions for such availability set forth in the
* Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
* version 2 with the GNU Classpath Exception, which is available at
* https://www.gnu.org/software/classpath/license.html.
*
* SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
*/
package javax.faces.render;
import java.io.IOException;
import java.util.Iterator;
import javax.faces.component.UIComponent;
import javax.faces.context.FacesContext;
import javax.faces.convert.ConverterException;
/**
* A Renderer converts
* the internal representation of {@link UIComponent}s into the output
* stream (or writer) associated with the response we are creating for a
* particular request. Each Renderer knows how to render
* one or more {@link UIComponent} types (or classes), and advertises a
* set of render-dependent attributes that it recognizes for each
* supported {@link UIComponent}.
*
* Families of {@link Renderer}s are packaged as a {@link RenderKit},
* and together support the rendering of all of the {@link UIComponent}s
* in a view associated with a {@link FacesContext}. Within the set of
* {@link Renderer}s for a particular {@link RenderKit}, each must be
* uniquely identified by the rendererType property.
*
* Individual {@link Renderer} instances will be instantiated as requested
* during the rendering process, and will remain in existence for the
* remainder of the lifetime of a web application. Because each instance
* may be invoked from more than one request processing thread simultaneously,
* they MUST be programmed in a thread-safe manner.
*
*
* If the {@link javax.faces.event.ListenerFor} annotation is
* attached to the class definition of a Renderer, that
* class must also implement {@link
* javax.faces.event.ComponentSystemEventListener}, and the action
* pertaining to the processing of ResourceDependency on a
* Renderer described in {@link
* javax.faces.event.ListenerFor} must be taken.
* If the {@link javax.faces.application.ResourceDependency}
* annotation is attached to the class definition of a
* Renderer, the action pertaining to the processing of
* ResourceDependency on a Renderer described
* in {@link UIComponent#getChildren} must be taken.
*
*/
public abstract class Renderer {
/**
* The key in the component passthrough
* attributes {@code Map} for the localName of the element corresponding to the component.
*
* @since 2.2
*/
public static final String PASSTHROUGH_RENDERER_LOCALNAME_KEY = "elementName";
// ------------------------------------------------------ Rendering Methods
/**
* Decode any new state of the specified {@link UIComponent}
* from the request contained in the specified {@link FacesContext},
* and store that state on the {@link UIComponent}.
*
* During decoding, events may be enqueued for later processing
* (by event listeners that have registered an interest), by calling
* queueEvent() on the associated {@link UIComponent}.
*
*
* @param context {@link FacesContext} for the request we are processing
* @param component {@link UIComponent} to be decoded.
*
* @throws NullPointerException if context
* or component is null
*/
public void decode(FacesContext context, UIComponent component) {
if (null == context || null == component) {
throw new NullPointerException();
}
}
/**
* Render the beginning specified {@link UIComponent} to the
* output stream or writer associated with the response we are creating.
* If the conversion attempted in a previous call to
* getConvertedValue() for this component failed, the state
* information saved during execution
* of decode() should be used to reproduce the incorrect
* input.
*
* @param context {@link FacesContext} for the request we are processing
* @param component {@link UIComponent} to be rendered
*
* @throws IOException if an input/output error occurs while rendering
* @throws NullPointerException if context
* or component is null
*/
public void encodeBegin(FacesContext context,
UIComponent component)
throws IOException {
if (null == context || null == component) {
throw new NullPointerException();
}
}
/**
* Render the child components of this {@link UIComponent}, following
* the rules described for encodeBegin() to acquire the
* appropriate value to be rendered. This method will only be called
* if the rendersChildren property of this component
* is true.
*
* @param context {@link FacesContext} for the response we are creating
* @param component {@link UIComponent} whose children are to be rendered
*
* @throws IOException if an input/output error occurs while rendering
* @throws NullPointerException if context
* or component is null
*/
public void encodeChildren(FacesContext context, UIComponent component)
throws IOException {
if (context == null || component == null) {
throw new NullPointerException();
}
if (component.getChildCount() > 0) {
Iterator kids = component.getChildren().iterator();
while (kids.hasNext()) {
UIComponent kid = kids.next();
kid.encodeAll(context);
}
}
}
/**
* Render the ending of the current state of the specified
* {@link UIComponent}, following the rules described for
* encodeBegin() to acquire the appropriate value
* to be rendered.
*
* @param context {@link FacesContext} for the response we are creating
* @param component {@link UIComponent} to be rendered
*
* @throws IOException if an input/output error occurs while rendering
* @throws NullPointerException if context
* or component is null
*/
public void encodeEnd(FacesContext context,
UIComponent component)
throws IOException {
if (null == context || null == component) {
throw new NullPointerException();
}
}
/**
* Convert the component generated client id to a form suitable
* for transmission to the client.
*
* The default implementation returns the argument
* clientId unchanged.
*
* @param context {@link FacesContext} for the current request
* @param clientId the client identifier to be converted to client a
* specific format.
*
* @throws NullPointerException if context
* or clientId is null
*
* @return the converted {@code clientId}
*/
public String convertClientId(FacesContext context, String clientId) {
if ((context == null) || (clientId == null)) {
throw new NullPointerException();
}
return (clientId);
}
/**
* Return a flag indicating whether this {@link Renderer} is responsible
* for rendering the children the component it is asked to render.
* The default implementation returns false.
*
* @return the current value of the flag
*/
public boolean getRendersChildren() {
return false;
}
/**
* Attempt to convert previously stored state information into an
* object of the type required for this component (optionally using the
* registered {@link javax.faces.convert.Converter} for this component,
* if there is one). If conversion is successful, the new value
* should be returned from this method; if not, a
* {@link ConverterException} should be thrown.
*
* @param context {@link FacesContext} for the request we are processing
* @param component {@link UIComponent} to be decoded.
* @param submittedValue a value stored on the component during
* decode.
*
* @throws ConverterException if the submitted value
* cannot be converted successfully.
* @throws NullPointerException if context
* or component is null
*
* @return the converted value
*/
public Object getConvertedValue(FacesContext context,
UIComponent component,
Object submittedValue)
throws ConverterException {
if ((context == null) || (component == null)) {
throw new NullPointerException();
}
return submittedValue;
}
}