PropertyUtils.java

/**
 * Copyright (c) 2010-2016 by the respective copyright holders.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 */
package org.openhab.binding.weather.internal.utils;

import java.lang.reflect.Field;

import org.apache.commons.lang.StringUtils;
import org.apache.commons.lang.reflect.FieldUtils;
import org.apache.commons.lang.reflect.MethodUtils;
import org.openhab.binding.weather.internal.model.Weather;

/**
 * Methods to get the value from a property or a getter method of an object.
 *
 * @author Gerhard Riegler
 * @since 1.6.0
 */
public class PropertyUtils {
    private static final String WEATHER_PROPERTY = Weather.class.getSimpleName().toLowerCase() + ".";

    /**
     * Returns the object of the (nested) property.
     */
    public static Object getNestedObject(Object instance, String propertyName) throws IllegalAccessException {
        if (PropertyUtils.isWeatherProperty(propertyName)) {
            return instance;
        }

        while (PropertyResolver.hasNested(propertyName)) {
            instance = FieldUtils.readField(instance, PropertyResolver.first(propertyName), true);
            propertyName = PropertyResolver.removeFirst(propertyName);
        }
        return instance;
    }

    /**
     * Returns true, if the property is a property from the weather object.
     */
    public static boolean isWeatherProperty(String property) {
        return StringUtils.startsWith(property, WEATHER_PROPERTY);
    }

    /**
     * Returns true, if the specified instance has the specified getter method.
     */
    public static boolean hasProperty(Object instance, String property) {
        try {
            getPropertyValue(instance, property);
            return true;
        } catch (Exception ex) {
            return false;
        }
    }

    /**
     * Returns the type name of the property of the instance.
     */
    public static String getPropertyTypeName(Object instance, String property) throws IllegalAccessException {
        Object object = getNestedObject(instance, property);
        Field field = FieldUtils.getField(object.getClass(), PropertyResolver.last(property), true);
        return field.getType().getCanonicalName();
    }

    /**
     * Returns the getter value from the object instance, nested properties are
     * possible. If the propertyName is for example temperature.current, the
     * methods getTemperature().getCurrent() are called.
     */
    public static Object getPropertyValue(Object instance, String property) throws Exception {
        Object object = getNestedObject(instance, property);
        String getMethod = toGetterString(PropertyResolver.last(property));
        return MethodUtils.invokeMethod(object, getMethod, null);
    }

    /**
     * Converts the string to a getter property.
     */
    private static String toGetterString(String str) {
        StringBuilder sb = new StringBuilder();
        sb.append("get");
        sb.append(Character.toTitleCase(str.charAt(0)));
        sb.append(str.substring(1));
        return sb.toString();
    }

}