com.feilong.lib.beanutils.FluentPropertyBeanIntrospector Maven / Gradle / Ivy
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 com.feilong.lib.beanutils;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Method;
import java.util.Locale;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
*
* An implementation of the BeanIntrospector interface which can
* detect write methods for properties used in fluent API scenario.
*
*
* A fluent API allows setting multiple properties using a single
* statement by supporting so-called method chaining: Methods for
* setting a property value do not return void, but an object which can
* be called for setting another property. An example of such a fluent API could
* look as follows:
*
*
* public class FooBuilder {
* public FooBuilder setFooProperty1(String value) {
* ...
* return this;
* }
*
* public FooBuilder setFooProperty2(int value) {
* ...
* return this;
* }
* }
*
*
* Per default, PropertyUtils does not detect methods like this
* because, having a non-void return type, they violate the Java Beans
* specification.
*
*
* This class is more tolerant with regards to the return type of a set method.
* It basically iterates over all methods of a class and filters them for a
* configurable prefix (the default prefix is set). It then
* generates corresponding PropertyDescriptor objects for the
* methods found which use these methods as write methods.
*
*
* An instance of this class is intended to collaborate with a
* {@link DefaultBeanIntrospector} object. So best results are achieved by
* adding this instance as custom {@code BeanIntrospector} after the
* DefaultBeanIntrospector object. Then default introspection finds
* read-only properties because it does not detect the write methods with a
* non-void return type. {@code FluentPropertyBeanIntrospector}
* completes the descriptors for these properties by setting the correct write
* method.
*
*
* @version $Id$
* @since 1.9
*/
public class FluentPropertyBeanIntrospector implements BeanIntrospector{
/** The default prefix for write methods. */
public static final String DEFAULT_WRITE_METHOD_PREFIX = "set";
/** The Constant log. */
private static final Logger LOGGER = LoggerFactory.getLogger(FluentPropertyBeanIntrospector.class);
//---------------------------------------------------------------
/** The prefix of write methods to search for. */
private final String writeMethodPrefix;
/**
*
* Creates a new instance of FluentPropertyBeanIntrospector and
* initializes it with the prefix for write methods used by the classes to
* be inspected.
*
* @param writePrefix
* the prefix for write methods (must not be null)
* @throws IllegalArgumentException
* if the prefix is null
*/
public FluentPropertyBeanIntrospector(final String writePrefix){
if (writePrefix == null){
throw new IllegalArgumentException("Prefix for write methods must not be null!");
}
writeMethodPrefix = writePrefix;
}
/**
*
* Creates a new instance of FluentPropertyBeanIntrospector and
* sets the default prefix for write methods.
*/
public FluentPropertyBeanIntrospector(){
this(DEFAULT_WRITE_METHOD_PREFIX);
}
/**
* Returns the prefix for write methods this instance scans for.
*
* @return the prefix for write methods
*/
public String getWriteMethodPrefix(){
return writeMethodPrefix;
}
/**
* Performs introspection. This method scans the current class's methods for
* property write methods which have not been discovered by default
* introspection.
*
* @param icontext
* the introspection context
* @throws IntrospectionException
* if an error occurs
*/
@Override
public void introspect(final IntrospectionContext icontext) throws IntrospectionException{
for (final Method m : icontext.getTargetClass().getMethods()){
if (m.getName().startsWith(getWriteMethodPrefix())){
final String propertyName = propertyName(m);
final PropertyDescriptor pd = icontext.getPropertyDescriptor(propertyName);
try{
if (pd == null){
icontext.addPropertyDescriptor(createFluentPropertyDescritor(m, propertyName));
}else if (pd.getWriteMethod() == null){
pd.setWriteMethod(m);
}
}catch (final IntrospectionException e){
LOGGER.info("Error when creating PropertyDescriptor for " + m + "! Ignoring this property.");
LOGGER.debug("Exception is:", e);
}
}
}
}
/**
* Derives the name of a property from the given set method.
*
* @param m
* the method
* @return the corresponding property name
*/
private String propertyName(final Method m){
final String methodName = m.getName().substring(getWriteMethodPrefix().length());
return (methodName.length() > 1) ? Introspector.decapitalize(methodName) : methodName.toLowerCase(Locale.ENGLISH);
}
/**
* Creates a property descriptor for a fluent API property.
*
* @param m
* the set method for the fluent API property
* @param propertyName
* the name of the corresponding property
* @return the descriptor
* @throws IntrospectionException
* if an error occurs
*/
private PropertyDescriptor createFluentPropertyDescritor(final Method m,final String propertyName) throws IntrospectionException{
return new PropertyDescriptor(propertyName(m), null, m);
}
}