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// -----------------------------------------------------------------------------
// LinkSet
// Copyright: 2010 Lukasz Bownik (lukasz.bownik@gmail.com)
//
// This file is part of LinkSet.
//
// LinkSet is free software; you can redistribute it and/or modify
// it under the terms of the Lesser GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// LinkSet is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// Lesser GNU General Public License for more details.
//
// You should have received a copy of the Lesser GNU General Public License
// along with LinkSet; if not, write to the Free Software
// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
// -----------------------------------------------------------------------------
package org.linkset;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
/*******************************************************************************
* A class dispatching commands.
*
* @author Łukasz Bownik
******************************************************************************/
public final class CommandExecutor {
/***************************************************************************
* A constructor
*
* @param target
* an objects that defines command execution methods.
**************************************************************************/
public CommandExecutor(final Object target) {
this.target = target;
for (final Method method : target.getClass().getDeclaredMethods()) {
final Executor executor = method.getAnnotation(Executor.class);
if (executor != null) {
final Class<?> parameters[] = method.getParameterTypes();
if (parameters.length != 1) {
throw new RuntimeException("Executor " + method
+ " must have only 1 parameter");
}
if (!parameters[0].equals(executor.cmdClass())) {
throw new RuntimeException("Executor " + method
+ " must have a parameter fo type: "
+ executor.cmdClass());
}
if (method.getReturnType().equals(Void.class)) {
throw new RuntimeException("Executor " + method
+ " must return value 'Null' suggested.");
}
method.setAccessible(true);
final Method prevoius = this.map.put(executor.cmdClass(),
method);
if (prevoius != null) {
throw new RuntimeException("Multiple executors found for: "
+ executor.cmdClass());
}
}
}
}
/***************************************************************************
* A method that executes a supplied command.
*
* @param command
* a command to execute
* @return return value of a command execution method.
* @throws a
* throwable thrown by command execution method.
**************************************************************************/
public Object execute(final Object command) throws Throwable {
final Method method = this.map.get(command.getClass());
if (method != null) {
try {
final Object result = method.invoke(this.target, command);
return result;
} catch (final InvocationTargetException e) {
throw e.getTargetException();
}
} else {
throw new RuntimeException("No executor found for: "
+ command.getClass());
}
}
/***************************************************************************
*
**************************************************************************/
private final HashMap<Class<?>, Method> map = new HashMap<Class<?>, Method>();
private final Object target;
}
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