新增 MapUtil.putSumValue(Map<String, BigDecimal>, String, Number)

[venusdrogon]

新增 MapUtil.putSumValue(Map<String, BigDecimal>, String, Number)

    /**
     * 将<code>key</code>和<code>value</code> 累加的形式put到 map中,如果<code>map</code>中存在<code>key</code>,那么累加<code>value</code>值;如果不存在那么直接put.
     * 
     * <p>
     * 常用于数据统计, 比如 {@link com.feilong.core.util.AggregateUtil#groupSum(Iterable, String, String)}
     * </p>
     * 
     * <h3>示例:</h3>
     * 
     * <blockquote>
     * 
     * <pre class="code">
     * 
     * Map{@code <String, BigDecimal>} map = new HashMap{@code <>}();
     * MapUtil.putSumValue(map, "1000001", 5);
     * MapUtil.putSumValue(map, "1000002", 5);
     * MapUtil.putSumValue(map, "1000002", 5);
     * LOGGER.debug(JsonUtil.format(map));
     * 
     * </pre>
     * 
     * <b>返回:</b>
     * 
     * <pre class="code">
     * {
     * "1000001": 5,
     * "1000002": 10
     * }
     * </pre>
     * 
     * </blockquote>
     * 
     * @param <K>
     *            the key type
     * @param map
     *            the map
     * @param key
     *            the key
     * @param value
     *            数值,不能为null,可以是负数
     * @return 如果 <code>map</code> 是null,抛出 {@link NullPointerException}<br>
     *         如果 <code>value</code> 是null,抛出 {@link NullPointerException}<br>
     * @see org.apache.commons.collections4.bag.HashBag
     * @see "java.util.Map#getOrDefault(Object, Object)"
     * @see <a href="http://stackoverflow.com/questions/81346/most-efficient-way-to-increment-a-map-value-in-java">most-efficient-way-to-
     *      increment-a-map-value-in-java</a>
     * @since 1.13.2
     */
    public static <K> Map<K, BigDecimal> putSumValue(Map<K, BigDecimal> map,K key,Number value){
        Validate.notNull(map, "map can't be null!");
        Validate.notNull(value, "value can't be null!");

        BigDecimal v = map.get(key);//这里不要使用 map.containsKey(key),否则会有2次  two potentially expensive operations
        map.put(key, null == v ? toBigDecimal(value) : NumberUtil.getAddValue(value, v));//Suggestion: you should care about code readability more than little performance gain in most of the time.
        return map;
    }