org.directwebremoting.faces.JsfCreator Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of dwr Show documentation
DWR is easy Ajax for Java. It makes it simple to call Java code directly from Javascript. It gets rid of almost all the boiler plate code between the web browser and your Java code.
There is a newer version: 3.0.2-RELEASE
Show newest version
/*
 * Copyright 2005 Joe Walker
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.directwebremoting.faces;

import javax.faces.application.Application;
import javax.faces.context.FacesContext;
import javax.faces.el.ValueBinding;
import javax.faces.el.VariableResolver;

import org.apache.commons.logging.LogFactory;
import org.apache.commons.logging.Log;
import org.directwebremoting.create.AbstractCreator;
import org.directwebremoting.extend.Creator;
import org.directwebremoting.util.LocalUtil;

/**
 * This is a DWR creator implementation, to allow dwr beans to be allocated into
 * JSF scopes and into jeffs3 specific scope (i.e. the flow scope)
 * @author Pierpaolo Follia
 * @author Joe Walker [joe at getahead dot ltd dot uk]
 * @author Vinicius Melo [vdmelo at gmail dot com]
 */
public class JsfCreator extends AbstractCreator implements Creator
{
    /* (non-Javadoc)
     * @see org.directwebremoting.Creator#getType()
     */
    public Class getType()
    {
        if (instanceType == null)
        {
            try
            {
                instanceType = getInstance().getClass();
            }
            catch (InstantiationException ex)
            {
                log.error("Failed to instansiate object to detect type.", ex);
                return Object.class;
            }
        }

        return instanceType;
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.Creator#getInstance()
     */
    public Object getInstance() throws InstantiationException
    {
        FacesContext facesContext = FacesContext.getCurrentInstance();
        if (facesContext == null)
        {
            log.error("Object " + getManagedBeanName() + " cannot be created since the faces context is null");
            return null;
        }

        Application application = facesContext.getApplication();
        Object resolvedObject = null;

        if (isVBExpression(getManagedBeanName()))
        {
            ValueBinding vb = application.createValueBinding(getManagedBeanName());
            if (vb != null)
            {
                resolvedObject = vb.getValue(facesContext);
            }
        }
        else
        {
            VariableResolver resolver = application.getVariableResolver();
            resolvedObject = resolver.resolveVariable(facesContext, getManagedBeanName());
        }

        return resolvedObject;
    }

    /**
     * Determine whether String is a value binding expression or not.
     * @param expression The expression to test for value bindingness
     * @return true if the expression contains a VB expression
     */
    public static boolean isVBExpression(String expression)
    {
        if (expression == null)
        {
            return false;
        }

        int start = expression.indexOf("#{");
        int end = expression.indexOf('}');

        return start != -1 && start < end;
    }

    /**
     * @return Returns the managedBeanName.
     */
    public String getManagedBeanName()
    {
        return managedBeanName;
    }

    /**
     * @param managedBeanName The managedBeanName to set.
     */
    public void setManagedBeanName(String managedBeanName)
    {
        this.managedBeanName = managedBeanName;
    }

    /**
     * What sort of class do we create?
     * @param classname The name of the class
     */
    public void setClass(String classname)
    {
        try
        {
            this.instanceType = LocalUtil.classForName(classname);
        }
        catch (ClassNotFoundException ex)
        {
            throw new IllegalArgumentException("Creator.ClassNotFound");
        }
    }

    /**
     * The name of the bean to get from the FacesContext
     */
    private String managedBeanName;

    /**
     * The cached type of bean that we are creating
     */
    private Class instanceType;

    /**
     * The log stream
     */
    private static final Log log = LogFactory.getLog(JsfCreator.class);
}