javax.mvc.engine

Interface ViewEngine

public interface ViewEngine

View engines are responsible for processing views and are discovered using CDI. Implementations must look up all instances of this interface, and process a view as follows:

1. Gather the set of candidate view engines by calling supports(String) and discarding engines that return false.
2. Sort the resulting set of candidates using priorities. View engines can be decorated with Priority to indicate their priority; otherwise the priority is assumed to be PRIORITY_APPLICATION.
3. If more than one candidate is available, choose one in an implementation-defined manner.
4. Fire a BeforeProcessViewEvent event.
5. Call method processView(ViewEngineContext) to process view.
6. Fire a AfterProcessViewEvent event.

The default view engines for JSPs and Facelets use file extensions to determine support. Namely, the default JSP view engine supports views with extensions jsp and jspx, and the one for Facelets supports views with extension xhtml.

Since:

1.0

Author:

Santiago Pericas-Geertsen

See Also:

Priority, BeforeProcessViewEvent

Field Summary

Fields

Modifier and Type	Field and Description
static String	DEFAULT_VIEW_FOLDER Default value for property VIEW_FOLDER.
static int	PRIORITY_APPLICATION Recommended priority for all application-provided view engines (default).
static int	PRIORITY_BUILTIN Priority for all built-in view engines.
static int	PRIORITY_FRAMEWORK Recommended priority for all view engines provided by frameworks built on top of MVC implementations.
static String	VIEW_FOLDER Name of property that can be set to override the root location for views in an archive.

Method Summary

Modifier and Type	Method and Description
void	processView(ViewEngineContext context) Process a view given a ViewEngineContext.
boolean	supports(String view) Returns true if this engine can process the view or false otherwise.

Field Detail

VIEW_FOLDER

static final String VIEW_FOLDER

Name of property that can be set to override the root location for views in an archive.

See Also:

Application.getProperties(), Constant Field Values

DEFAULT_VIEW_FOLDER

static final String DEFAULT_VIEW_FOLDER

Default value for property VIEW_FOLDER.

See Also:

Constant Field Values

PRIORITY_BUILTIN

static final int PRIORITY_BUILTIN

Priority for all built-in view engines.

See Also:

Constant Field Values

PRIORITY_FRAMEWORK

static final int PRIORITY_FRAMEWORK

Recommended priority for all view engines provided by frameworks built on top of MVC implementations.

See Also:

Constant Field Values

PRIORITY_APPLICATION

static final int PRIORITY_APPLICATION

Recommended priority for all application-provided view engines (default).

See Also:

Constant Field Values

Method Detail

supports

boolean supports(String view)

Returns true if this engine can process the view or false otherwise.

Parameters:

view - the view.

Returns:

outcome of supports test.

processView

void processView(ViewEngineContext context)
          throws ViewEngineException

Process a view given a ViewEngineContext. Processing a view involves merging the model and template data and writing the result to an output stream.

Following the Java EE threading model, the underlying view engine implementation must support this method being called by different threads. Any resources allocated during view processing must be released before the method returns.

Parameters:

context - the context needed for processing.

Throws:

ViewEngineException - if an error occurs during processing.