echoxul.view
Class ViewComponent

java.lang.Object
  nextapp.echo.Component
      echoxul.view.ViewComponent

All Implemented Interfaces:

java.io.Serializable

public class ViewComponent

extends nextapp.echo.Component

This component serves as a base class for implementing components which are derived from a View. Children should NOT be added to this component explicitly.

During the time between construction and initialization, the subclass or the user of the component must specify the resource location used to lookup the concrete View instance from the ViewCache. Setting the resource location multiple times prior to init() being called results in only the last setting being honored. This allows a subclass to specify a default during construction which can be overriden by the user of the component prior to init().

There are several ways to set the resource location:

• Using the constructor ViewComponent(String)
• Calling the setViewResource(String) method
• Calling the setView(View) method
• Calling the setViewContext(ViewContext) method

Both the constructor and the setViewResource(String) method expect a "resource location" string. This string is a path-like structure which will be resolved by the registered implementation of ViewCache (@see ViewCache). While different implementations of ViewCache can implement custom syntaxes, the following syntaxes will always be supported:

• A java resource reference to be retrieved from the classpath. The syntax of this definition consists of the string "res:" followed by the path (delimitted with forward slashes) to the resource. If the path portion begins with a forward slash, the resolution is done absolutely. Otherwise, the resolution is done relative to the package of the current view class (as defined by getClass()). The resource is always loaded from the ClassLoader which loaded the EchoXul runtime library (which will usually have the expected results).
  Examples:
  • Loading a resource "foo" from package "com.xyz": res:/com/xyz/foo
  • Loading a relative resource "foo" from the package containing the current class: res:foo
• Loading an external resource. The actual manner of storage and locations of external resources is defined by the ViewCache registered at runtime. However, every ViewCache provides an absolute location where all resources are located. Accessing resources in this location is simple a matter of specifying a path within this defined area. The path must start with a forward slash and cannot contain relative directory traversal segments (ie. ".." or "."). The default ViewCache loads its resources with the Servlet.getResource(...) method. This means that all resources are (by default) resolved relative to the web site root. In addition, the default implementation appends well known suffixes in its search for the resources. For example, a resource path of "/foo" would load the first resource found with the name "/foo", "/foo.xml", "/foo.xhtml", "/foo.xul".

Subclass init() methods must always call super.init() as their first step. After the base class init() method has been called, the call to getViewContext() will be guaranteed to succeed and allows access to the virtual component hierarchy.

Author:

Terry Laurenzo

See Also:

Serialized Form

Field Summary

Fields inherited from class nextapp.echo.Component

BACKGROUND_CHANGED_PROPERTY, CHILDREN_CHANGED_PROPERTY, ENABLED_CHANGED_PROPERTY, FONT_CHANGED_PROPERTY, FOREGROUND_CHANGED_PROPERTY, IDENTIFIER_CHANGED_PROPERTY, listenerList, LOCALE_CHANGED_PROPERTY, MODEL_CHANGED_PROPERTY, STYLE_BACKGROUND, STYLE_FONT, STYLE_FOREGROUND, UPDATE_PROPERTY, VISIBLE_CHANGED_PROPERTY

Constructor Summary

ViewComponent()
Default "do-nothing" constructor

ViewComponent(java.lang.String resourcePath)
Construct a ViewComponent with a default resourcePath

Method Summary

ViewContext	getViewContext() Return the ViewContext that this instance is wrapping.
protected void	init()
void	setResourcePath(java.lang.String resourcePath)
void	setView(View view)
void	setViewContext(ViewContext viewContext)

Methods inherited from class nextapp.echo.Component

add, add, addHierarchyListener, addPropertyChangeListener, applyStyle, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getBackground, getComponent, getComponentCount, getComponents, getEchoInstance, getFont, getForeground, getIdentifier, getLocale, getParent, indexOf, isAncestorOf, isEnabled, isRegistered, isShowing, isVisible, remove, remove, removeAll, removeHierarchyListener, removePropertyChangeListener, setBackground, setEnabled, setFont, setForeground, setIdentifier, setLocale, setVisible, update, validate

Methods inherited from class java.lang.Object

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

Constructor Detail

ViewComponent

public ViewComponent()

Default "do-nothing" constructor

ViewComponent

public ViewComponent(java.lang.String resourcePath)

Construct a ViewComponent with a default resourcePath

Parameters:

resourcePath -

Method Detail

setResourcePath

public void setResourcePath(java.lang.String resourcePath)

setViewContext

public void setViewContext(ViewContext viewContext)

setView

public void setView(View view)

init

protected void init()

getViewContext

public ViewContext getViewContext()

Return the ViewContext that this instance is wrapping. Only valid after init() has been executed.

Returns:

The ViewContext which this instance is wrapping.