/*
* 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.tags.core;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.jelly.JellyTagException;
import org.apache.commons.jelly.MissingAttributeException;
import org.apache.commons.jelly.TagSupport;
import org.apache.commons.jelly.XMLOutput;
import org.apache.commons.jelly.util.ClassLoaderUtils;
/**
* A Tag which can invoke a static method on a class, without an
* instance of the class being needed.
* <p>
* Like the {@link InvokeTag}, this tag can take a set of
* arguments using the {@link ArgTag}.
* </p>
* <p>
* The following attributes are required:<br />
* <ul>
* <li>var - The variable to assign the return of the method call to</li>
* <li>method - The name of the static method to invoke</li>
* <li>className - The name of the class containing the static method</li>
* </ul>
* </p>
*
* @author <a href="mailto:robert@bull-enterprises.com>Robert McIntosh</a>
* @version $Revision: 1.9 $
*/
public class InvokeStaticTag extends TagSupport implements ArgTagParent {
/** the variable exported */
private String var;
/** the variable where the method's exception is exported */
private String exceptionVar;
/** the method to invoke */
private String methodName;
/** the object to invoke the method on */
private String className;
private List paramTypes = new ArrayList();
private List paramValues = new ArrayList();
public InvokeStaticTag() {
}
/**
* Sets the name of the variable exported by this tag
*
* @param var The variable name
*/
public void setVar(String var) {
this.var = var;
}
/** Sets the name of a variable that exports the exception thrown by
* the method's invocation (if any)
*/
public void setExceptionVar(String var) {
this.exceptionVar = var;
}
/**
* Sets the name of the method to invoke
*
* @param method The method name
*/
public void setMethod(String methodName) {
this.methodName = methodName;
}
/**
* Sets the fully qualified class name containing the static method
*
* @param className The name of the class
*/
public void setClassName(String className) {
this.className = className;
}
/**
* Adds an argument to supply to the method
*
* @param type The Class type of the argument
* @param value The value of the argument
*/
public void addArgument(Class type, Object value) {
paramTypes.add(type);
paramValues.add(value);
}
// Tag interface
//-------------------------------------------------------------------------
public void doTag(XMLOutput output) throws JellyTagException {
try {
if ( null == methodName) {
throw new MissingAttributeException( "method" );
}
invokeBody(output);
Object[] values = paramValues.toArray();
Class[] types = (Class[])(paramTypes.toArray(new Class[paramTypes.size()]));
Method method = loadClass().getMethod( methodName, types );
Object result = method.invoke( null, values );
if(null != var) {
context.setVariable(var, result);
}
ArgTag parentArg = (ArgTag)(findAncestorWithClass(ArgTag.class));
if(null != parentArg) {
parentArg.setValue(result);
}
}
catch (ClassNotFoundException e) {
throw createLoadClassFailedException(e);
}
catch (NoSuchMethodException e) {
throw createLoadClassFailedException(e);
}
catch (IllegalAccessException e) {
throw createLoadClassFailedException(e);
}
catch (InvocationTargetException e) {
if(null != exceptionVar) {
context.setVariable(exceptionVar,e.getTargetException());
} else {
throw new JellyTagException("method " + methodName +
" threw exception: "+ e.getTargetException().getMessage(),
e.getTargetException() );
}
}
finally {
paramTypes.clear();
paramValues.clear();
}
}
// Tag interface
//-------------------------------------------------------------------------
/**
* Loads the class using either the class loader which loaded me or the
* current threads context class loader
*/
protected Class loadClass() throws ClassNotFoundException {
return ClassLoaderUtils.loadClass(className, getClass());
}
/**
* Factory method to create a new JellyTagException instance from a given
* failure exception
* @param e is the exception which occurred attempting to load the class
* @return JellyTagException
*/
protected JellyTagException createLoadClassFailedException(Exception e) {
return new JellyTagException(
"Could not load class: " + className + ". Reason: " + e, e
);
}
}