Mega Code Archive
Property access utility methods
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/*
* Copyright 2004, 2005, 2006 Odysseus Software GmbH
*
* 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.
*/
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
/**
* Property access utility methods.
*
* @author Christoph Beck
*/
public class PropertyUtils {
private static HashMap descriptorCache = new HashMap();
/**
* Get map with property descriptors for the specified bean class
*/
private static Map getPropertyDescriptors(Class clazz) {
HashMap map = (HashMap)descriptorCache.get(clazz);
if (map == null) {
BeanInfo beanInfo = null;
try {
beanInfo = Introspector.getBeanInfo(clazz);
} catch (IntrospectionException e) {
return Collections.EMPTY_MAP;
}
PropertyDescriptor[] descriptors = beanInfo.getPropertyDescriptors();
if (descriptors == null)
descriptors = new PropertyDescriptor[0];
map = new HashMap(descriptors.length);
for (int i = 0; i < descriptors.length; i++)
map.put(descriptors[i].getName(), descriptors[i]);
descriptorCache.put(clazz, map);
}
return map;
}
/**
* Get property names of the specified bean class
*/
public static Iterator getPropertyNames(Class clazz) {
return getPropertyDescriptors(clazz).keySet().iterator();
}
/**
* Get specified property descriptor
*/
public static PropertyDescriptor getPropertyDescriptor(Class clazz, String property) {
return (PropertyDescriptor)getPropertyDescriptors(clazz).get(property);
}
/**
* Get specified property value
*/
public static Object getProperty(Object bean, String property) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException {
PropertyDescriptor descriptor = getPropertyDescriptor(bean.getClass(), property);
if (descriptor == null)
throw new NoSuchMethodException("Cannot find property " + bean.getClass().getName() + "." + property);
Method method = descriptor.getReadMethod();
if (method == null)
throw new NoSuchMethodException("Cannot find getter for " + bean.getClass().getName() + "." + property);
return method.invoke(bean, null);
}
/**
* Get specified nested property value
*/
public static Object getNestedProperty(Object bean, String property) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException {
if (property.indexOf('.') > 0) {
String[] path = property.split("\\.");
for (int i = 0; i < path.length && bean != null; i++) {
bean = getProperty(bean, path[i]);
}
return bean;
} else {
return getProperty(bean, property);
}
}
/**
* Set specified property value
*/
public static void setProperty(Object bean, String property, Object value) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException {
PropertyDescriptor descriptor = getPropertyDescriptor(bean.getClass(), property);
if (descriptor == null)
throw new NoSuchMethodException("Cannot find property " + bean.getClass().getName() + "." + property);
Method method = descriptor.getWriteMethod();
if (method == null)
throw new NoSuchMethodException("Cannot find setter for " + bean.getClass().getName() + "." + property);
method.invoke(bean, new Object[]{ value });
}
/**
* Set nested property given by property path, starting at specified
* index. Dynamically create beans if necessary. Take care not to
* leave the bean changed if an exception occurs.
*/
private static void setNestedPropertyWithCreate(Object bean, String[] path, int start, Object value) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException, InstantiationException {
for (int i = start; i < path.length - 1; i++) {
Object object = getProperty(bean, path[i]);
if (object == null) {
PropertyDescriptor descr =
getPropertyDescriptor(bean.getClass(), path[i]);
object = descr.getPropertyType().newInstance();
setNestedPropertyWithCreate(object, path, i + 1, value);
setProperty(bean, path[i], object);
return;
}
bean = object;
}
setProperty(bean, path[path.length - 1], value);
}
/**
* Set specified nested property value
*/
public static void setNestedProperty(Object bean, String property, Object value) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException, InstantiationException {
int lastDot = property.lastIndexOf('.');
if (lastDot > 0) {
setNestedPropertyWithCreate(bean, property.split("\\."), 0, value);
} else {
setProperty(bean, property, value);
}
}
}
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