org.springframework.binding.method.MethodInvoker.java Source code

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Here is the source code for org.springframework.binding.method.MethodInvoker.java

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/*
 * Copyright 2004-2012 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.binding.method;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.binding.convert.ConversionService;
import org.springframework.binding.convert.service.DefaultConversionService;
import org.springframework.core.style.StylerUtils;
import org.springframework.util.CachingMapDecorator;

/**
 * A helper for invoking typed methods on arbitrary objects, with support for argument value type conversion from values
 * retrieved from an argument attribute source, and conversion of the result to a desired type.
 * 
 * @author Keith Donald
 * @author Jeremy Grelle
 */
public class MethodInvoker {

    private static final Log logger = LogFactory.getLog(MethodInvoker.class);

    /**
     * Conversion service for converting arguments to the necessary type if required.
     */
    private ConversionService conversionService = new DefaultConversionService();

    /**
     * A cache of invoked bean methods, keyed weakly.
     */
    private CachingMapDecorator<MethodKey, Method> methodCache = new CachingMapDecorator<MethodKey, Method>(true) {
        public Method create(MethodKey key) {
            return key.getMethod();
        }
    };

    /**
     * Sets the conversion service to convert argument values as needed.
     */
    public void setConversionService(ConversionService conversionService) {
        this.conversionService = conversionService;
    }

    /**
     * Invoke the method on the bean provided. Argument values are pulled from the provided argument source.
     * @param signature the definition of the method to invoke, including the method name and the method argument types
     * @param bean the bean to invoke
     * @param argumentSource the source for method arguments
     * @return the invoked method's return value
     * @throws MethodInvocationException the method could not be invoked
     */
    public Object invoke(MethodSignature signature, Object bean, Object argumentSource)
            throws MethodInvocationException {
        Parameters parameters = signature.getParameters();
        Object[] arguments = new Object[parameters.size()];
        for (int i = 0; i < parameters.size(); i++) {
            Parameter parameter = parameters.getParameter(i);
            Object argument = parameter.evaluateArgument(argumentSource);
            arguments[i] = applyTypeConversion(argument, parameter.getType());
        }
        Class<?>[] parameterTypes = parameters.getTypesArray();
        for (int i = 0; i < parameterTypes.length; i++) {
            if (parameterTypes[i] == null) {
                Object argument = arguments[i];
                if (argument != null) {
                    parameterTypes[i] = argument.getClass();
                }
            }
        }
        MethodKey key = new MethodKey(bean.getClass(), signature.getMethodName(), parameterTypes);
        try {
            Method method = methodCache.get(key);
            if (logger.isDebugEnabled()) {
                logger.debug("Invoking method with signature [" + key + "] with arguments "
                        + StylerUtils.style(arguments) + " on bean [" + bean + "]");

            }
            Object returnValue = method.invoke(bean, arguments);
            if (logger.isDebugEnabled()) {
                logger.debug("Invoked method with signature [" + key + "] returned value [" + returnValue + "]");
            }
            return returnValue;
        } catch (InvocationTargetException e) {
            throw new MethodInvocationException(signature, arguments, e.getTargetException());
        } catch (Exception e) {
            throw new MethodInvocationException(signature, arguments, e);
        }
    }

    /**
     * Apply type conversion on the supplied value
     * 
     * @param value the raw value to be converted
     * @param targetType the target type for the conversion
     * @return the converted result
     */
    protected Object applyTypeConversion(Object value, Class<?> targetType) {
        if (value == null || targetType == null) {
            return value;
        }
        return conversionService.getConversionExecutor(value.getClass(), targetType).execute(value);
    }
}