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Spring Framework example source code file (ArgumentConvertingMethodInvoker.java)

This example Spring Framework source code file (ArgumentConvertingMethodInvoker.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Spring Framework tags/keywords

argumentconvertingmethodinvoker, bean, illegalstateexception, javabean, method, method, methodinvoker, object, object, propertyeditorregistry, propertyeditorregistry, reflection, simpletypeconverter, string, typeconverter, typeconverter, typemismatchexception

The Spring Framework ArgumentConvertingMethodInvoker.java source code

/*
 * 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 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;
	}

}

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