将集合和数组转化成字符串

	/**
	 * 把一个集合转化成一个字符串，null或size为0时转化为空串
	 */
	public static String collToStr(Collection c, String delimiter) {
		if (c == null || c.size() == 0) {
			return "";
		}

		Iterator it = c.iterator();

		StringBuilder sb = new StringBuilder(cleanToStr(it.next()));

		while (it.hasNext()) {
			sb.append(delimiter);
			sb.append(cleanToStr(it.next()));
		}

		return sb.toString();
	}

	/**
	 * 把一个数组转化成一个字符串，null或size为0时转化为空串
	 */
	public static String arrayToStr(Object[] os, String delimiter) {
		if (os == null || os.length == 0) {
			return "";
		}

		StringBuilder sb = new StringBuilder(cleanToStr(os[0]));

		for(int i = 1; i< os.length; i++){
			sb.append(delimiter);
			sb.append(cleanToStr(os[i]));
		}

		return sb.toString();
	}