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'databene commons' is an open source Java library by Volker Bergmann.
It provides extensions to the Java core library by utility classes, abstract concepts
and concrete implementations.
/*
* Copyright (C) 2004-2014 Volker Bergmann ([email protected]).
* All rights reserved.
*
* 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.databene.commons.bean;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.HashMap;
import java.util.Map;
import org.databene.commons.ArrayUtil;
import org.databene.commons.ConfigurationError;
import org.databene.commons.StringUtil;
/**
* Creates {@link ObservableBean} implementations from interfaces.
*
* Created at 17.07.2008 14:57:53
* @since 0.4.5
* @author Volker Bergmann
*/
public class ObservableFactory {
@SuppressWarnings("unchecked")
public static E create(Class type) {
if (!type.isInterface())
throw new ConfigurationError("Not an interface: " + type);
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
ObservableBeanInvocationHandler handler = new ObservableBeanInvocationHandler(type);
E bean = (E) Proxy.newProxyInstance(classLoader, new Class[] { type }, handler);
return bean;
}
private static class ObservableBeanInvocationHandler implements InvocationHandler {
private Map propertyValues = new HashMap();
private PropertyChangeSupport support;
private Class type;
public ObservableBeanInvocationHandler(Class type) {
this.type = type;
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
if (support == null)
this.support = new PropertyChangeSupport(proxy);
String methodName = method.getName();
if (methodName.startsWith("get") && ArrayUtil.isEmpty(args)) {
String propertyName = methodName.substring(3);
propertyName = StringUtil.uncapitalize(propertyName);
return propertyValues.get(propertyName);
} else if (methodName.startsWith("set")) {
String propertyName = methodName.substring(3);
propertyName = StringUtil.uncapitalize(propertyName);
Object oldValue = propertyValues.get(propertyName);
propertyValues.put(propertyName, args[0]);
support.firePropertyChange(propertyName, oldValue, args[0]);
} else if ("addPropertyChangeListener".equals(methodName)) {
if (args.length == 2)
support.addPropertyChangeListener((String) args[0], (PropertyChangeListener) args[1]);
else
support.addPropertyChangeListener((PropertyChangeListener) args[0]);
} else if ("removePropertyChangeListener".equals(methodName)) {
if (args.length == 2)
support.removePropertyChangeListener((String) args[0], (PropertyChangeListener) args[1]);
else
support.removePropertyChangeListener((PropertyChangeListener) args[0]);
} else if ("equals".equals(methodName)) {
Object other = args[0];
if (proxy == other)
return true;
if (other == null)
return false;
if (!proxy.getClass().equals(other.getClass()))
return false;
ObservableBeanInvocationHandler otherHandler = (ObservableBeanInvocationHandler) Proxy.getInvocationHandler(proxy);
return (this.propertyValues.equals(otherHandler.propertyValues));
} else if ("hashCode".equals(methodName)) {
return propertyValues.hashCode();
} else if ("toString".equals(methodName)) {
return type.getName() + propertyValues;
} else
throw new UnsupportedOperationException("Operation not supported: " + method);
return null;
}
}
}