字符串添加换行

	private static String  lineSeparator(String str) {
		int p=0, i=0;
		StringBuffer sb2 = new StringBuffer(str);
		int size = 0;
		while((p = str.indexOf(",",p+1))>-1) {
			i++;
			if(i%3==0) {
				sb2.insert(p+size+1, System.lineSeparator());
				size+=2;
			}
		}
		return sb2.toString();
	}