private static void recordFile(long time,boolean isBuffer)
            throws FileNotFoundException, IOException {
    	BufferedWriter bw = new BufferedWriter(new FileWriter("log",true));
    	bw.write("FILE_COUNT = "+FILE_COUNT+";对"+ ITEM_COUNT + "条数据 "+ ITEM_COUNT*4/(1024*1204) +"MB排序耗时:" + time + "s ");
    	if(isBuffer){
    		bw.write("  使用缓冲:"+BUFFER_SIZE*4/(1024*1204) +"MB");
    	}
    	bw.newLine();
    	bw.close();
    }