Application: gvSIG desktop

package org.gvsig.expressionevaluator.impl;

import java.lang.reflect.Method;

import org.apache.commons.lang3.StringUtils;

/**

 *

 * @author jjdelcerro

 */

public class InstanceUtils {

    public static Object callmethod(Object instance, String methodName, Object args[]) throws Exception {

        if( StringUtils.isBlank(methodName) ) {

            throw new NullPointerException("A method name was expected to invoke and a null was received");

        }

        if( instance==null ) {

            throw new NullPointerException("An object pointer was expected to invoke method "+methodName+" and a null was received");

        }

        Class<?> theClass = instance.getClass();

        Method method = getMethod(theClass, methodName, createParameterTypesAccurate(args));

        if( method == null ) {

            method = getMethod(theClass, methodName, createParameterTypesFuzzy(theClass, methodName, args));

        }

        if( method == null ) {

            method = getMethod(theClass, methodName, createParameterTypesAllObjects(args));

        }

        if( method == null ) {

            method = getMethod(theClass, methodName, createParameterTypesFromMethodNameAndParametersCount(theClass, methodName, args));

        }

        Object value = method.invoke(instance, args);

        return value;

    }

    private static Method getMethod(Class theClass, String methodName, Class[] parameterTypes) {

        if( parameterTypes==null ) {

            return null;

        }

        try {

            return theClass.getMethod(methodName, parameterTypes);

        } catch(NoSuchMethodException ex) {

        }

        return null;

    }

    private static Class[] createParameterTypesAccurate(Object[] parameters) {

        Class[] parameterTypes = new Class[parameters.length];

        for (int i = 0; i < parameters.length; i++) {

            Object parameter = parameters[i];

            parameters[i] = parameter;

            if( parameter==null ) {

                parameterTypes[i] = null;

            } else {

                parameterTypes[i] = parameter.getClass();

            }

        }

        return parameterTypes;

    }

    private static Class[] createParameterTypesAllObjects(Object[] parameters) {

        Class[] parameterTypes = new Class[parameters.length];

        for (int i = 0; i < parameters.length; i++) {

            Object parameter = parameters[i];

            parameters[i] = parameter;

            if( parameter==null ) {

                parameterTypes[i] = null;

            } else {

                parameterTypes[i] = Object.class;

            }

        }

        return parameterTypes;

    }

    private static Class[] createParameterTypesFromMethodNameAndParametersCount(Class theClass, String methodName, Object[] parameters) {

        for (Method m : theClass.getMethods()) {

            if( StringUtils.equals(m.getName(), methodName) && parameters.length == m.getParameterTypes().length) {

                return m.getParameterTypes();

            }

        }

        return null;

    }

    private static Class[] createParameterTypesFuzzy(Class theClass, String methodName, Object[] parameters) {

        for (Method m : theClass.getMethods()) {

            if( StringUtils.equals(m.getName(), methodName) && parameters.length == m.getParameterTypes().length) {

                int n = 0;

                Class[] parameterTypes = new Class[parameters.length];

                for (Class<?> expectedType : m.getParameterTypes()) {

                    Class<? extends Object> paramType = parameters[n].getClass();

                    if( expectedType == paramType ) {

                        parameterTypes[n++] = expectedType;

                        continue;

                    }

                    if( expectedType == Object.class ) {

                        parameterTypes[n++] = Object.class;

                        continue;

                    }

                    //

                    // Aqui probablemente habria que hacer algunas otras 

                    // comprobaciones, por ejemplo, si expected es double y

                    // recibimos un entero, long o float... ? deberiamos

                    // aceptar ? ? Habria que convertir el valor a double ?

                    //

                    parameterTypes = null;

                    break;

                }

                if( parameterTypes!=null ) {

                    return parameterTypes;

                }

            }

        }

        return null;

    }

}