/*
* Copyright 2002,2004 The Apache Software Foundation.
*
* 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.apache.commons.jelly.impl;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashSet;
import java.util.Iterator;
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.JellyTagException;
import org.apache.commons.jelly.MissingAttributeException;
import org.apache.commons.jelly.Tag;
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: 155420 $
*/
public class DynamicBeanTag extends DynaBeanTagSupport implements BeanSource {
/** The Log to which logging calls will be made. */
private static final Log log = LogFactory.getLog(DynamicBeanTag.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;
/**
*
* @param beanClass Class of the bean that will receive the setter events
* @param attributes
* @param variableNameAttribute
* @param method method of the Bean to invoke after the attributes have been set. Can be null.
*/
public DynamicBeanTag(Class beanClass, Map attributes, String variableNameAttribute, Method method) {
this.beanClass = beanClass;
this.method = method;
this.attributes = attributes;
this.variableNameAttribute = variableNameAttribute;
}
public void beforeSetAttributes() throws JellyTagException {
// create a new dynabean before the attributes are set
try {
bean = beanClass.newInstance();
setDynaBean( new ConvertingWrapDynaBean( bean ) );
} catch (InstantiationException e) {
throw new JellyTagException("Could not instantiate dynabean",e);
} catch (IllegalAccessException e) {
throw new JellyTagException("Could not instantiate dynabean",e);
}
setAttributesSet.clear();
}
public void setAttribute(String name, Object value) throws JellyTagException {
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 JellyTagException {
// 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);
}
}
}
// If the dynamic bean is itself a tag, let it execute itself
if (bean instanceof Tag)
{
Tag tag = (Tag) bean;
tag.setBody(getBody());
tag.setContext(getContext());
tag.setParent(getParent());
((Tag) bean).doTag(output);
return;
}
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) {
methodInvocationException(bean, method, e);
}
catch (IllegalArgumentException e) {
methodInvocationException(bean, method, e);
}
catch (InvocationTargetException e) {
// methodInvocationError(bean, method, e);
Throwable inner = e.getTargetException();
throw new JellyTagException(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 methodInvocationException(Object bean, Method method, Exception e) throws JellyTagException {
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 new JellyTagException(e);
}
// Properties
//-------------------------------------------------------------------------
/**
* @return the bean that has just been created
*/
public Object getBean() {
return bean;
}
}