Java tutorial
/* * Copyright 2011-2013 the original author or authors. * * 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.springframework.scala.beans; import java.awt.Image; import java.beans.BeanDescriptor; import java.beans.BeanInfo; import java.beans.EventSetDescriptor; import java.beans.IntrospectionException; import java.beans.Introspector; import java.beans.MethodDescriptor; import java.beans.PropertyDescriptor; import java.lang.reflect.Method; import java.util.Comparator; import java.util.Map; import java.util.TreeMap; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.util.Assert; import org.springframework.util.ReflectionUtils; /** * Implementation of {@link BeanInfo} for Scala classes. Decorates a standard {@link * BeanInfo} object by including Scala setter methods (ending in {@code _$eq} in the * collection of {@linkplain #getPropertyDescriptors() property descriptors}. * * @author Arjen Poutsma */ class ScalaBeanInfo implements BeanInfo { private static final Log logger = LogFactory.getLog(ScalaBeanInfo.class); private static final String SCALA_SETTER_SUFFIX = "_$eq"; private final BeanInfo delegate; private final PropertyDescriptor[] propertyDescriptors; public ScalaBeanInfo(Class<?> beanClass) throws IntrospectionException { this(Introspector.getBeanInfo(beanClass)); } public ScalaBeanInfo(BeanInfo delegate) throws IntrospectionException { Assert.notNull(delegate, "'delegate' must not be null"); this.delegate = delegate; this.propertyDescriptors = initPropertyDescriptors(delegate); } private static PropertyDescriptor[] initPropertyDescriptors(BeanInfo beanInfo) { Map<String, PropertyDescriptor> propertyDescriptors = new TreeMap<String, PropertyDescriptor>( new PropertyNameComparator()); for (PropertyDescriptor pd : beanInfo.getPropertyDescriptors()) { propertyDescriptors.put(pd.getName(), pd); } for (MethodDescriptor md : beanInfo.getMethodDescriptors()) { Method method = md.getMethod(); if (ReflectionUtils.isObjectMethod(method)) { continue; } if (isScalaSetter(method)) { addScalaSetter(propertyDescriptors, method); } else if (isScalaGetter(method)) { addScalaGetter(propertyDescriptors, method); } } return propertyDescriptors.values().toArray(new PropertyDescriptor[propertyDescriptors.size()]); } private static boolean isScalaGetter(Method method) { return method.getParameterTypes().length == 0 && !method.getReturnType().equals(Void.TYPE) && !(method.getName().startsWith("get") || method.getName().startsWith("is")); } public static boolean isScalaSetter(Method method) { return method.getParameterTypes().length == 1 && method.getReturnType().equals(Void.TYPE) && method.getName().endsWith(SCALA_SETTER_SUFFIX); } private static void addScalaSetter(Map<String, PropertyDescriptor> propertyDescriptors, Method writeMethod) { String propertyName = writeMethod.getName().substring(0, writeMethod.getName().length() - SCALA_SETTER_SUFFIX.length()); PropertyDescriptor pd = propertyDescriptors.get(propertyName); if (pd != null && pd.getWriteMethod() == null) { try { pd.setWriteMethod(writeMethod); } catch (IntrospectionException ex) { logger.debug("Could not add write method [" + writeMethod + "] for " + "property [" + propertyName + "]: " + ex.getMessage()); } } else if (pd == null) { try { pd = new PropertyDescriptor(propertyName, null, writeMethod); propertyDescriptors.put(propertyName, pd); } catch (IntrospectionException ex) { logger.debug("Could not create new PropertyDescriptor for " + "writeMethod [" + writeMethod + "] property [" + propertyName + "]: " + ex.getMessage()); } } } private static void addScalaGetter(Map<String, PropertyDescriptor> propertyDescriptors, Method readMethod) { String propertyName = readMethod.getName(); PropertyDescriptor pd = propertyDescriptors.get(propertyName); if (pd != null && pd.getReadMethod() == null) { try { pd.setReadMethod(readMethod); } catch (IntrospectionException ex) { logger.debug("Could not add read method [" + readMethod + "] for " + "property [" + propertyName + "]: " + ex.getMessage()); } } else if (pd == null) { try { pd = new PropertyDescriptor(propertyName, readMethod, null); propertyDescriptors.put(propertyName, pd); } catch (IntrospectionException ex) { logger.debug("Could not create new PropertyDescriptor for " + "readMethod [" + readMethod + "] property [" + propertyName + "]: " + ex.getMessage()); } } } public PropertyDescriptor[] getPropertyDescriptors() { return propertyDescriptors; } public BeanInfo[] getAdditionalBeanInfo() { return delegate.getAdditionalBeanInfo(); } public BeanDescriptor getBeanDescriptor() { return delegate.getBeanDescriptor(); } public int getDefaultEventIndex() { return delegate.getDefaultEventIndex(); } public int getDefaultPropertyIndex() { return delegate.getDefaultPropertyIndex(); } public EventSetDescriptor[] getEventSetDescriptors() { return delegate.getEventSetDescriptors(); } public Image getIcon(int iconKind) { return delegate.getIcon(iconKind); } public MethodDescriptor[] getMethodDescriptors() { return delegate.getMethodDescriptors(); } /** * Sorts property names alphanumerically to emulate the behavior of {@link * java.beans.BeanInfo#getPropertyDescriptors()}. */ private static class PropertyNameComparator implements Comparator<String> { public int compare(String left, String right) { byte[] leftBytes = left.getBytes(); byte[] rightBytes = right.getBytes(); for (int i = 0; i < left.length(); i++) { if (right.length() == i) { return 1; } int result = leftBytes[i] - rightBytes[i]; if (result != 0) { return result; } } return left.length() - right.length(); } } }