StringBuilder json = new StringBuilder();
			json.append('[');
			for(Video video : videos){ // {id:76,title:"xxxx",timelength:80}
				json.append('{');
				json.append("id:").append(video.getId()).append(',');
				json.append("title:\"").append(video.getTitle()).append("\",");
				json.append("timelength:").append(video.getTime());
				json.append('}').append(',');
			}
			json.deleteCharAt(json.length()-1);
			json.append(']');