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'rapiddweller Common' is an open source Java library forked from Databene Commons by Volker Bergmann. It provides extensions to the Java core library by utility classes, abstract concepts and concrete implementations.
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/*
 * Copyright (C) 2004-2015 Volker Bergmann ([email protected]).
 * All rights reserved.
 *
 * 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 com.rapiddweller.common.accessor;

import com.rapiddweller.common.Accessor;
import com.rapiddweller.common.BeanUtil;
import com.rapiddweller.common.Composite;
import com.rapiddweller.common.ConfigurationError;
import com.rapiddweller.common.Context;
import com.rapiddweller.common.Escalator;
import com.rapiddweller.common.LoggerEscalator;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Map;

/**
 * Get values from Maps, Contexts, Composites and JavaBeans.
 * Created: 12.06.2007 18:36:11
 *
 * @param  the object type to access
 * @param  the type of the value to get from the object
 * @author Volker Bergmann
 */
public class FeatureAccessor implements Accessor {

  private static final Logger LOGGER = LogManager.getLogger(FeatureAccessor.class);

  private static final Escalator escalator = new LoggerEscalator();

  private String featureName;

  // constructors ----------------------------------------------------------------------------------------------------

  /**
   * Instantiates a new Feature accessor.
   *
   * @param featureName the feature name
   */
  public FeatureAccessor(String featureName) {
    this(featureName, true);
  }

  /**
   * Instantiates a new Feature accessor.
   *
   * @param featureName the feature name
   * @param strict      the strict
   */
  public FeatureAccessor(String featureName, boolean strict) {
    LOGGER.debug("FeatureAccessor({}, {})", featureName, strict);
    this.featureName = featureName;
  }

  /**
   * Gets feature name.
   *
   * @return the feature name
   */
  public String getFeatureName() {
    return featureName;
  }

  /**
   * Sets feature name.
   *
   * @param featureName the feature name
   */
  public void setFeatureName(String featureName) {
    this.featureName = featureName;
  }

  // Accessor interface implementation -------------------------------------------------------------------------------

  @Override
  @SuppressWarnings("unchecked")
  public V getValue(C target) {
    return (V) getValue(target, featureName);
  }

  // static convenience methods --------------------------------------------------------------------------------------

  /**
   * Gets value.
   *
   * @param target      the target
   * @param featureName the feature name
   * @return the value
   */
  public static Object getValue(Object target, String featureName) {
    LOGGER.debug("getValue({}, {})", target, featureName);
    return getValue(target, featureName, true);
  }

  /**
   * Gets value.
   *
   * @param target      the target
   * @param featureName the feature name
   * @param required    the required
   * @return the value
   */
  @SuppressWarnings("unchecked")
  public static Object getValue(Object target, String featureName, boolean required) {
    if (target == null) {
      return null;
    } else if (target instanceof Map) {
      return ((Map) target).get(featureName);
    } else if (target instanceof Context) {
      return ((Context) target).get(featureName);
    } else if (target instanceof Composite) {
      return ((Composite) target).getComponent(featureName);
    } else {
      // try generic get(String) method
      Method genericGetMethod = BeanUtil.findMethod(target.getClass(), "get", String.class);
      if (genericGetMethod != null) {
        return BeanUtil.invoke(target, genericGetMethod, new Object[] {featureName});
      }
      // try JavaBean property
      PropertyDescriptor propertyDescriptor = BeanUtil.getPropertyDescriptor(target.getClass(), featureName);
      if (propertyDescriptor != null && propertyDescriptor.getReadMethod() != null) {
        try {
          return propertyDescriptor.getReadMethod().invoke(target);
        } catch (Exception e) {
          throw new ConfigurationError("Unable to read property '" + featureName + "'", e);
        }
      } else {
        Class type = ((target instanceof Class) ? (Class) target : target.getClass());
        Field field = BeanUtil.getField(type, featureName);
        if (field != null) {
          return BeanUtil.getFieldValue(field, target, false);
        }
      }
    }
    // the feature has not been identified, yet - escalate or raise an exception
    if (required) {
      throw new UnsupportedOperationException(
          target.getClass() + " does not support a feature '" + featureName + "'");
    } else {
      escalator.escalate("Feature '" + featureName + "' not found in object " + target, FeatureAccessor.class, null);
    }
    return null;
  }

  // java.lang.Object overrides --------------------------------------------------------------------------------------

  @Override
  public String toString() {
    return getClass().getSimpleName() + '[' + featureName + ']';
  }
}