这段代码是什么意思

private MediaFilePath dayOverFilePath;
private String suffixStr = ".dat";
private String prefixStr = "";
private final Logger logger = Logger.getLogger(this.getClass());

@Override
public List<String> getFilePathListByDateFilter(String merchtNo,
String startDate, String endDate,String status) throws BusinessException {
if(status.equals("zf")){
prefixStr="";
}else{
prefixStr="REF";
}
List<Object> listo = new ArrayList<Object>();
List<String> list = new ArrayList<String>();
String filePath = dayOverFilePath.getFilePath() + merchtNo;
logger.debug("文件路径地址"+filePath);
String datestr = startDate.substring(0, startDate.length() - 2);

try {
File file = new File(filePath);
FileFilter filter = new PrefixFileFilter(prefixStr+merchtNo + datestr);

File[] files = file.listFiles(filter);

if(files != null ){
for (File tem : files) {
String fileName = tem.getName();
String subStr = fileName.substring((prefixStr+merchtNo).length(), fileName
.indexOf(suffixStr));

if (Long.parseLong(subStr) >= Long.parseLong(startDate)
&& Long.parseLong(subStr) <= Long.parseLong(endDate)) {

AccontCheck ac=new AccontCheck();
ac.setMerchtNo(merchtNo);
ac.setName(tem.getName());
ac.setDate(Long.parseLong(subStr));
listo.add(ac);
// list.add("/" + merchtNo + "/" + tem.getName());
}

}
//排序
ListSort listSort =new ListSort();
Collections.sort(listo,listSort);
for (int i = 0; i < listo.size(); i++) {
AccontCheck ac=(AccontCheck)listo.get(i);
list.add("/"+ac.getMerchtNo()+"/"+ac.getName());
}
} else {
logger.error("无此【"+merchtNo+"】的对账文件保存目录");
}
} catch (Exception e) {
logger.error(e.getMessage(), e);
throw new BusinessException("搜索文件错误！");
}

return list;
}