Package org.apache.commons.jelly.tags.define

Source Code of org.apache.commons.jelly.tags.define.BeanTag

/*
* $Header: /home/cvs/jakarta-commons-sandbox/jelly/src/java/org/apache/commons/jelly/tags/define/DynamicTag.java,v 1.7 2002/05/17 15:18:12 jstrachan Exp $
* $Revision: 1.7 $
* $Date: 2002/05/17 15:18:12 $
*
* ====================================================================
*
* The Apache Software License, Version 1.1
*
* Copyright (c) 1999-2002 The Apache Software Foundation.  All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in
*    the documentation and/or other materials provided with the
*    distribution.
*
* 3. The end-user documentation included with the redistribution, if
*    any, must include the following acknowlegement:
*       "This product includes software developed by the
*        Apache Software Foundation (http://www.apache.org/)."
*    Alternately, this acknowlegement may appear in the software itself,
*    if and wherever such third-party acknowlegements normally appear.
*
* 4. The names "The Jakarta Project", "Commons", and "Apache Software
*    Foundation" must not be used to endorse or promote products derived
*    from this software without prior written permission. For written
*    permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache"
*    nor may "Apache" appear in their names without prior written
*    permission of the Apache Group.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation.  For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
* $Id: DynamicTag.java,v 1.7 2002/05/17 15:18:12 jstrachan Exp $
*/
package org.apache.commons.jelly.tags.define;

import java.lang.reflect.Method;
import java.lang.reflect.InvocationTargetException;
import java.util.Iterator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Set;

import org.apache.commons.beanutils.ConvertingWrapDynaBean;

import org.apache.commons.collections.BeanMap;

import org.apache.commons.jelly.DynaBeanTagSupport;
import org.apache.commons.jelly.JellyContext;
import org.apache.commons.jelly.JellyException;
import org.apache.commons.jelly.MissingAttributeException;
import org.apache.commons.jelly.Script;
import org.apache.commons.jelly.TagSupport;
import org.apache.commons.jelly.XMLOutput;
import org.apache.commons.jelly.expression.Expression;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
* This tag is bound onto a Java Bean class. When the tag is invoked a bean will be created
* using the tags attributes.
* The bean may also have an invoke method called invoke(), run(), execute() or some such method
* which will be invoked after the bean has been configured.</p>
*
* @author <a href="mailto:jstrachan@apache.org">James Strachan</a>
* @author <a href="mailto:jason@zenplex.com">Jason van Zyl</a>
* @version $Revision: 1.7 $
*/
public class BeanTag extends DynaBeanTagSupport {

    /** The Log to which logging calls will be made. */
    private static final Log log = LogFactory.getLog(BeanTag.class);

    /** Empty arguments for Method.invoke() */
    private static final Object[] emptyArgs = {};
   
    /** the bean class */
    private Class beanClass;
   
    /** the current bean instance */
    private Object bean;
   
    /** the method to invoke on the bean */
    private Method method;   

    /**
     * the tag attribute name that is used to declare the name
     * of the variable to export after running this tag
     */
    private String variableNameAttribute;

    /** the current variable name that the bean should be exported as */
    private String var;

    /** the set of attribute names we've already set */
    private Set setAttributesSet = new HashSet();

    /** the attribute definitions */
    private Map attributes;   
       
    public BeanTag(Class beanClass, Map attributes, String variableNameAttribute, Method method) {
        this.beanClass = beanClass;
        this.method = method;
        this.attributes = attributes;
        this.variableNameAttribute = variableNameAttribute;
    }

    public void beforeSetAttributes() throws Exception {
        // create a new dynabean before the attributes are set
        bean = beanClass.newInstance();
        setDynaBean( new ConvertingWrapDynaBean( bean ) );

        setAttributesSet.clear();                   
    }

    public void setAttribute(String name, Object value) throws Exception {       
        boolean isVariableName = false;
        if (variableNameAttribute != null ) {
            if ( variableNameAttribute.equals( name ) ) {
                if (value == null) {
                    var = null;
                }
                else {
                    var = value.toString();
                }
                isVariableName = true;
            }
        }
        if (! isVariableName) {
           
            // #### strictly speaking we could
            // know what attributes are specified at compile time
            // so this dynamic set is unnecessary           
            setAttributesSet.add(name);
           
            // we could maybe implement attribute specific validation here
           
            super.setAttribute(name, value);
        }
    }

    // Tag interface
    //-------------------------------------------------------------------------                   
    public void doTag(XMLOutput output) throws Exception {

        // lets find any attributes that are not set and
        for ( Iterator iter = attributes.values().iterator(); iter.hasNext(); ) {
            Attribute attribute = (Attribute) iter.next();
            String name = attribute.getName();
            if ( ! setAttributesSet.contains( name ) ) {
                if ( attribute.isRequired() ) {
                    throw new MissingAttributeException(name);
                }
                // lets get the default value
                Object value = null;
                Expression expression = attribute.getDefaultValue();
                if ( expression != null ) {
                    value = expression.evaluate(context);
                }
               
                // only set non-null values?
                if ( value != null ) {
                    super.setAttribute(name, value);
                }
            }
        }
       
        invokeBody(output);

        // export the bean if required
        if ( var != null ) {
            context.setVariable(var, bean);
        }
       
        // now, I may invoke the 'execute' method if I have one
        if ( method != null ) {
            try {
                method.invoke( bean, emptyArgs );
            }
            catch (IllegalAccessException e) {
                methodInvocationError(bean, method, e);
            }
            catch (IllegalArgumentException e) {
                methodInvocationError(bean, method, e);
            }
            catch (InvocationTargetException e) {
                // methodInvocationError(bean, method, e);

                Throwable inner = e.getTargetException();

                if ( inner instanceof Exception )
                {
                    throw (Exception) inner;
                }
                else
                {
                    throw new JellyException( inner );
                }
            }
        }
    }
   
    /**
     * Report the state of the bean when method invocation fails
     * so that the user can determine any problems that might
     * be occuring while using dynamic jelly beans.
     *
     * @param bean Bean on which <code>method</code was invoked
     * @param method Method that was invoked
     * @param e Exception throw when <code>method</code> was invoked
     */
    private void methodInvocationError(Object bean, Method method, Exception e) throws Exception {
        log.error("Could not invoke " + method, e);
        BeanMap beanMap = new BeanMap(bean);
       
        log.error("Bean properties:");
        for (Iterator i = beanMap.keySet().iterator(); i.hasNext();) {
            String property = (String) i.next();
            Object value = beanMap.get(property);
            log.error(property + " -> " + value);
        }
       
        log.error(beanMap);
        throw e;
    }
   
    // Properties
    //-------------------------------------------------------------------------                   
    /**
     * @return the bean that has just been created
     */
    public Object getBean() {
        return bean;
    }
}
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