/*
* Copyright 2002-2008 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.beans.support;
import java.beans.PropertyEditor;
import java.lang.reflect.Method;
import org.springframework.beans.PropertyEditorRegistry;
import org.springframework.beans.SimpleTypeConverter;
import org.springframework.beans.TypeConverter;
import org.springframework.beans.TypeMismatchException;
import org.springframework.util.MethodInvoker;
import org.springframework.util.ReflectionUtils;
/**
* Subclass of {@link MethodInvoker} that tries to convert the given
* arguments for the actual target method via a {@link TypeConverter}.
*
* <p>Supports flexible argument conversions, in particular for
* invoking a specific overloaded method.
*
* @author Juergen Hoeller
* @since 1.1
* @see org.springframework.beans.BeanWrapperImpl#convertIfNecessary
*/
public class ArgumentConvertingMethodInvoker extends MethodInvoker {
private TypeConverter typeConverter;
private boolean useDefaultConverter = true;
/**
* Set a TypeConverter to use for argument type conversion.
* <p>Default is a {@link org.springframework.beans.SimpleTypeConverter}.
* Can be overridden with any TypeConverter implementation, typically
* a pre-configured SimpleTypeConverter or a BeanWrapperImpl instance.
* @see org.springframework.beans.SimpleTypeConverter
* @see org.springframework.beans.BeanWrapperImpl
*/
public void setTypeConverter(TypeConverter typeConverter) {
this.typeConverter = typeConverter;
this.useDefaultConverter = false;
}
/**
* Return the TypeConverter used for argument type conversion.
* <p>Can be cast to {@link org.springframework.beans.PropertyEditorRegistry}
* if direct access to the underlying PropertyEditors is desired
* (provided that the present TypeConverter actually implements the
* PropertyEditorRegistry interface).
*/
public TypeConverter getTypeConverter() {
if (this.typeConverter == null && this.useDefaultConverter) {
this.typeConverter = getDefaultTypeConverter();
}
return this.typeConverter;
}
/**
* Obtain the default TypeConverter for this method invoker.
* <p>Called if no explicit TypeConverter has been specified.
* The default implementation builds a
* {@link org.springframework.beans.SimpleTypeConverter}.
* Can be overridden in subclasses.
*/
protected TypeConverter getDefaultTypeConverter() {
return new SimpleTypeConverter();
}
/**
* Register the given custom property editor for all properties of the given type.
* <p>Typically used in conjunction with the default
* {@link org.springframework.beans.SimpleTypeConverter}; will work with any
* TypeConverter that implements the PropertyEditorRegistry interface as well.
* @param requiredType type of the property
* @param propertyEditor editor to register
* @see #setTypeConverter
* @see org.springframework.beans.PropertyEditorRegistry#registerCustomEditor
*/
public void registerCustomEditor(Class requiredType, PropertyEditor propertyEditor) {
TypeConverter converter = getTypeConverter();
if (!(converter instanceof PropertyEditorRegistry)) {
throw new IllegalStateException(
"TypeConverter does not implement PropertyEditorRegistry interface: " + converter);
}
((PropertyEditorRegistry) converter).registerCustomEditor(requiredType, propertyEditor);
}
/**
* This implementation looks for a method with matching parameter types.
* @see #doFindMatchingMethod
*/
protected Method findMatchingMethod() {
Method matchingMethod = super.findMatchingMethod();
// Second pass: look for method where arguments can be converted to parameter types.
if (matchingMethod == null) {
// Interpret argument array as individual method arguments.
matchingMethod = doFindMatchingMethod(getArguments());
}
if (matchingMethod == null) {
// Interpret argument array as single method argument of array type.
matchingMethod = doFindMatchingMethod(new Object[] {getArguments()});
}
return matchingMethod;
}
/**
* Actually find a method with matching parameter type, i.e. where each
* argument value is assignable to the corresponding parameter type.
* @param arguments the argument values to match against method parameters
* @return a matching method, or <code>null</code> if none
*/
protected Method doFindMatchingMethod(Object[] arguments) {
TypeConverter converter = getTypeConverter();
if (converter != null) {
String targetMethod = getTargetMethod();
Method matchingMethod = null;
int argCount = arguments.length;
Method[] candidates = ReflectionUtils.getAllDeclaredMethods(getTargetClass());
int minTypeDiffWeight = Integer.MAX_VALUE;
Object[] argumentsToUse = null;
for (int i = 0; i < candidates.length; i++) {
Method candidate = candidates[i];
if (candidate.getName().equals(targetMethod)) {
// Check if the inspected method has the correct number of parameters.
Class[] paramTypes = candidate.getParameterTypes();
if (paramTypes.length == argCount) {
Object[] convertedArguments = new Object[argCount];
boolean match = true;
for (int j = 0; j < argCount && match; j++) {
// Verify that the supplied argument is assignable to the method parameter.
try {
convertedArguments[j] = converter.convertIfNecessary(arguments[j], paramTypes[j]);
}
catch (TypeMismatchException ex) {
// Ignore -> simply doesn't match.
match = false;
}
}
if (match) {
int typeDiffWeight = getTypeDifferenceWeight(paramTypes, convertedArguments);
if (typeDiffWeight < minTypeDiffWeight) {
minTypeDiffWeight = typeDiffWeight;
matchingMethod = candidate;
argumentsToUse = convertedArguments;
}
}
}
}
}
if (matchingMethod != null) {
setArguments(argumentsToUse);
return matchingMethod;
}
}
return null;
}
}