executionresolver.java

非常接近C/S操作方式的Java Ajax框架－ZK 用ZK框架使你的B/S应用程序更漂亮更易操作。 官网：www.zkoss.org

/* ExecutionResolver.java

{{IS_NOTE
	Purpose:
		
	Description:
		
	History:
		Fri Jun 24 12:22:23     2005, Created by tomyeh
}}IS_NOTE

Copyright (C) 2005 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
	This program is distributed under GPL Version 2.0 in the hope that
	it will be useful, but WITHOUT ANY WARRANTY.
}}IS_RIGHT
*/
package org.zkoss.zk.ui.impl;

import java.util.Collections;

import javax.servlet.jsp.el.VariableResolver;
import javax.servlet.jsp.el.ELException;

import org.zkoss.zk.ui.Execution;
import org.zkoss.zk.ui.Page;
import org.zkoss.zk.ui.Component;
import org.zkoss.zk.ui.UiException;
import org.zkoss.zk.ui.sys.ExecutionCtrl;
import org.zkoss.zk.ui.sys.Variables;

/**
 * Represents a variable resolver.
 *
 * @author tomyeh
 */
public class ExecutionResolver implements VariableResolver {
	/** The parent resolver. */
	private final VariableResolver _parent;
	private final Execution _exec;
	private Object _self;

	/** Constructs a resolver with a parent and a page.
	 * @param parent the parent resolver (null means ignored).
	 * @param exec the current execution
	 */
	public ExecutionResolver(Execution exec, VariableResolver parent) {
		if (exec == null) throw new NullPointerException();
		_exec = exec;
		_parent = parent;
	}

	/** Sets the self variable.
	 * The self variable also acts as the context to resolve other variables.
	 */
	public void setSelf(Object self) {
		_self = self;
	}

	//-- VariableResolver --//
	public Object resolveVariable(String name) throws ELException {
		if ("self".equals(name))
			return _self;
		if ("pageScope".equals(name)) {
			if (_self instanceof Component)
				return ((Component)_self).getAttributes(Component.PAGE_SCOPE);
			if (_self instanceof Page)
				return ((Page)_self).getAttributes();
			final Page page = ((ExecutionCtrl)_exec).getCurrentPage();
			return page != null ? page.getAttributes(): Collections.EMPTY_MAP;
		}
		if ("page".equals(name)) {
			if (_self instanceof Component)
				return ((Component)_self).getPage();
			if (_self instanceof Page)
				return (Page)_self;
			return ((ExecutionCtrl)_exec).getCurrentPage();
		}
		if ("spaceOwner".equals(name)) {
			if (_self instanceof Component)
				return ((Component)_self).getSpaceOwner();
			if (_self instanceof Page)
				return (Page)_self;
			return null;
		}
		if ("desktopScope".equals(name))
			return _exec.getDesktop().getAttributes();
		if ("desktop".equals(name))
			return _exec.getDesktop();
		if ("spaceScope".equals(name)) {
			if (_self instanceof Component)
				return ((Component)_self).getAttributes(Component.SPACE_SCOPE);
			if (_self instanceof Page)
				return ((Page)_self).getAttributes();
			return Collections.EMPTY_MAP;
		}
		if ("componentScope".equals(name)) {
			if (_self instanceof Component)
				return ((Component)_self).getAttributes(Component.COMPONENT_SCOPE);
			return Collections.EMPTY_MAP;
		}
		if ("requestScope".equals(name))
			return _exec.getAttributes();
		if ("arg".equals(name))
			return _exec.getArg();

		if (!Variables.isReserved(name)){
			Page page = null;
			if (_self instanceof Component) {
				final Component comp = (Component)_self;
				final Object o = comp.getVariable(name, false);
				if (o != null)
					return o;
				page = comp.getPage();
			} else if (_self instanceof Page) {
				page = (Page)_self;
			}
			if (page == null)
				page = ((ExecutionCtrl)_exec).getCurrentPage();
			if (page != null) {
				final Object o = page.getVariable(name);
				if (o != null)
					return o;
			}
		}
		return _parent != null ? _parent.resolveVariable(name): null;
	}
}