acromusashi.stream.bean.FieldExtractor.java Source code

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Here is the source code for acromusashi.stream.bean.FieldExtractor.java

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/**
* Copyright (c) Acroquest Technology Co, Ltd. All Rights Reserved.
* Please read the associated COPYRIGHTS file for more details.
*
* THE SOFTWARE IS PROVIDED BY Acroquest Technolog Co., Ltd.,
* WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
* BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDER BE LIABLE FOR ANY
* CLAIM, DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING
* OR DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
*/
package acromusashi.stream.bean;

import java.util.Map;

import org.apache.commons.lang.StringUtils;
import org.springframework.beans.BeanWrapperImpl;

/**
 * ?EL???
 * 
 * @author kimura
 */
public class FieldExtractor {
    /**
     * Constructor
     */
    private FieldExtractor() {
    }

    /**
     * Extract field 
     * 
     * @param target is used to get object data.
     * @param key is used to get key value.
     * @param delimeter key delimeter
     * @return is used to return object data.
     */
    public static Object extract(Object target, String key, String delimeter) {
        if (target == null) {
            return target;
        }

        String keyHead = extractKeyHead(key, delimeter); // the return value of keyHead 
        String keyTail = extractKeyTail(key, delimeter); // the return value of keyTail 

        Object innerObject = null;

        // checking if the "Object: target" is Map or not
        if (target instanceof Map) {
            Map<?, ?> targetMap = (Map<?, ?>) target;
            innerObject = targetMap.get(keyHead); // get the object inside "keyHead"
        } else {
            BeanWrapperImpl baseWapper = new BeanWrapperImpl(target); // this is the reflection for getting the field value.
            innerObject = baseWapper.getPropertyValue(keyHead); // get the value from the field if the "keyHead" is not Map
        }

        if (innerObject == null) {
            return innerObject;
        }

        if (StringUtils.isEmpty(keyTail) == true) {
            return innerObject;
        } else {
            return extract(innerObject, keyTail, delimeter); // recursive method for calling self function again.
        }
    }

    /**
     * Extract the value of keyHead.
     * 
     * @param key is used to get string.
     * @param delimeter key delimeter
     * @return the  value of keyHead .
     */
    public static String extractKeyHead(String key, String delimeter) {
        int index = key.indexOf(delimeter);
        if (index == -1) {
            return key;
        }

        String result = key.substring(0, index);
        return result;
    }

    /**
     * Extract the value of keyTail.
     * 
     * @param key is used to get string.
     * @param delimeter key delimeter
     * @return the  value of keyTail .
     */
    public static String extractKeyTail(String key, String delimeter) {
        int index = key.indexOf(delimeter);
        if (index == -1) {
            return null;
        }
        String result = key.substring(index + delimeter.length());
        return result;
    }
}