ELUtil.java

//
// Copyright © 2014, David Tesler (https://github.com/protobufel)
// All rights reserved.
//
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// modification, are permitted provided that the following conditions are met:
// * Redistributions of source code must retain the above copyright
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// names of its contributors may be used to endorse or promote products
// derived from this software without specific prior written permission.
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package com.github.protobufel.el;

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

import javax.el.ELContext;
import javax.el.ELException;

/**
 * EL Utilities.
 *
 * @author protobufel@gmail.com David Tesler
 */
public final class ELUtil {
  private ELUtil() {}

  public static Object invokeMethod(final ELContext context, final Method m, final Object base,
      final Object[] params) {
    final Class<?>[] parameterTypes = m.getParameterTypes();
    Object[] parameters = null;

    if (parameterTypes.length > 0) {
      if (m.isVarArgs() && (params.length < (parameterTypes.length - 1))) {
        throw new ELException(new IllegalArgumentException("wrong number of arguments"));
      }

      parameters = new Object[params.length];
      final int normalParamLength =
          m.isVarArgs() ? parameterTypes.length - 1 : parameterTypes.length;

      for (int i = 0; i < normalParamLength; i++) {
        parameters[i] = context.convertToType(params[i], parameterTypes[i]);
      }

      if (m.isVarArgs() && (params.length > normalParamLength)) {
        final Class<?> varArgsType = parameterTypes[normalParamLength];

        for (int i = normalParamLength; i < params.length; i++) {
          parameters[i] = context.convertToType(params[i], varArgsType);
        }
      }
    }

    try {
      return m.invoke(base, parameters);
    } catch (final IllegalAccessException iae) {
      throw new ELException(iae);
    } catch (final InvocationTargetException ite) {
      throw new ELException(ite.getCause());
    }
  }

}