防止重名，需要重命名
public class FileRenameUtil {
public static StringBuffer fileRename(){
SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMddHHmmssSSS");
String time = sdf.format(new Date());
StringBuffer buf = new StringBuffer(time);
Random r = new Random();
for(int x=0;x<3;x++){//循环取得三个不大于10的随机整数
buf.append(r.nextInt(10));
}
return buf;
}
}