Renderer (Java EE 5 SDK)

javax.faces.render Class Renderer

java.lang.Object
  javax.faces.render.Renderer

public abstract class Renderer

extends Object

A Renderer converts the internal representation of UIComponents 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 UIComponent types (or classes), and advertises a set of render-dependent attributes that it recognizes for each supported UIComponent.

Families of Renderers are packaged as a RenderKit, and together support the rendering of all of the UIComponents in a view associated with a FacesContext. Within the set of Renderers for a particular RenderKit, each must be uniquely identified by the rendererType property.

Individual 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.

Renderer

public Renderer()

decode

public void decode(FacesContext context,
                   UIComponent component)

Decode any new state of the specified UIComponent from the request contained in the specified FacesContext, and store that state on the UIComponent.

During decoding, events may be enqueued for later processing (by event listeners that have registered an interest), by calling queueEvent() on the associated UIComponent.

参数:

context - FacesContext for the request we are processing

component - UIComponent to be decoded.

抛出异常:

NullPointerException - if context or component is null

encodeBegin

public void encodeBegin(FacesContext context,
                        UIComponent component)
                 throws IOException

Render the beginning specified 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.

参数:

context - FacesContext for the request we are processing

component - UIComponent to be rendered

抛出异常:

IOException - if an input/output error occurs while rendering

NullPointerException - if context or component is null

encodeChildren

public void encodeChildren(FacesContext context,
                           UIComponent component)
                    throws IOException

Render the child components of this 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.

参数:

context - FacesContext for the response we are creating

component - UIComponent whose children are to be rendered

抛出异常:

IOException - if an input/output error occurs while rendering

NullPointerException - if context or component is null

encodeEnd

public void encodeEnd(FacesContext context,
                      UIComponent component)
               throws IOException

Render the ending of the current state of the specified UIComponent, following the rules described for encodeBegin() to acquire the appropriate value to be rendered.

参数:

context - FacesContext for the response we are creating

component - UIComponent to be rendered

抛出异常:

IOException - if an input/output error occurs while rendering

NullPointerException - if context or component is null

convertClientId

public String convertClientId(FacesContext context,
                              String clientId)

Convert the component generated client id to a form suitable for transmission to the client.

The default implementation returns the argument clientId unchanged.

参数:

context - FacesContext for the current request

clientId - the client identifier to be converted to client a specific format.

抛出异常:

NullPointerException - if context or clientId is null

getRendersChildren

public boolean getRendersChildren()

Return a flag indicating whether this Renderer is responsible for rendering the children the component it is asked to render. The default implementation returns false.

getConvertedValue

public Object getConvertedValue(FacesContext context,
                                UIComponent component,
                                Object submittedValue)
                         throws ConverterException

Attempt to convert previously stored state information into an object of the type required for this component (optionally using the registered Converter for this component, if there is one). If conversion is successful, the new value should be returned from this method; if not, a ConverterException should be thrown.

参数:

context - FacesContext for the request we are processing

component - UIComponent to be decoded.

submittedValue - a value stored on the component during decode.

抛出异常:

ConverterException - if the submitted value cannot be converted successfully.

NullPointerException - if context or component is null

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