com.njmd.framework.utils.CollectionsUtil.java Source code

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Here is the source code for com.njmd.framework.utils.CollectionsUtil.java

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/**
 * Copyright (c) 2005-2012 springside.org.cn
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 */
package com.njmd.framework.utils;

import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.apache.commons.beanutils.PropertyUtils;
import org.apache.commons.lang3.StringUtils;

/**
 * Collections. JDKColllectionsGuavaCollections2?, ??Collections3.
 * 
 * @author calvin
 */
public class CollectionsUtil {

    private CollectionsUtil() {
    }

    public static <T> List<T> subtract(final Collection<T> a, final Collection<T> b) {
        ArrayList<T> list = new ArrayList<T>(a);
        for (Iterator it = b.iterator(); it.hasNext();) {
            list.remove(it.next());
        }
        return list;
    }

    /**
     * ????(Getter), ??Map.
     * 
     * @param collection
     *            ???.
     * @param keyPropertyName
     *            ????MapKey??.
     * @param valuePropertyName
     *            ????MapValue??.
     */
    public static Map extractToMap(final Collection collection, final String keyPropertyName,
            final String valuePropertyName) {
        Map map = new HashMap();

        try {
            for (Object obj : collection) {
                map.put(PropertyUtils.getProperty(obj, keyPropertyName),
                        PropertyUtils.getProperty(obj, valuePropertyName));
            }
        } catch (Exception e) {
            throw ReflectionUtil.convertReflectionExceptionToUnchecked(e);
        }

        return map;
    }

    /**
     * ????(Getter), ??List.
     * 
     * @param collection
     *            ???.
     * @param propertyName
     *            ??????.
     */
    public static List extractToList(final Collection collection, final String propertyName) {
        List list = new ArrayList();

        try {
            for (Object obj : collection) {
                list.add(PropertyUtils.getProperty(obj, propertyName));
            }
        } catch (Exception e) {
            throw ReflectionUtil.convertReflectionExceptionToUnchecked(e);
        }

        return list;
    }

    /**
     * ????(Getter), ??.
     * 
     * @param collection
     *            ???.
     * @param propertyName
     *            ??????.
     * @param separator
     *            .
     */
    public static String extractToString(final Collection collection, final String propertyName,
            final String separator) {
        List list = extractToList(collection, propertyName);
        return StringUtils.join(list, separator);
    }
}