对于我的项目,我需要从FTP服务器下载一个zip文件,该服务器每年发布一次新的zip文件大约13次。我需要按照服务器的命名约定下载最新文件:
Prefix + release number (one or two digits) + year (two digits) + suffix + ".zip"
例如:
ALFP1016F.zip
前缀总是相同(ALFP),后缀是F或P(代表“完整”或“部分”;我只需要以后缀F结尾的文件)。最重要的是,我需要忽略的目录中还有其他几个文件,因为它们有不同的前缀。然后,我需要按照此优先级顺序获取数组中的最新文件:
例如,如果我有这个文件名列表(full server directory):
1stpage712.pdf
1stpage914.pdf
ALFP1015F.zip
ALFP1015P.zip
ALFP716F.zip
ALFP716P.zip
FSFP816F.zip
FSFP816P.zip
我的预期产量是
ALFP716F.zip
因为16是最近的一年,7是该年度最新的版本号
这是我到目前为止所做的:
//necessary imports
import org.apache.commons.net.ftp.FTP;
import org.apache.commons.net.ftp.FTPClient;
import org.apache.commons.net.ftp.FTPFile;
//initialize FTP client
ftpClient = new FTPClient();
try {
//connect to server
ftpClient.connect(server, port);
ftpClient.login(username, password);
ftpClient.enterLocalPassiveMode();
ftpClient.setFileType(FTP.BINARY_FILE_TYPE);
//list all names from server
String[] filenames = ftpClient.listNames();
//return expected file name
String expectedFileName = returnMostRecent(filenames);
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (ftpClient.isConnected()) {
ftpClient.logout();
ftpClient.disconnect();
System.out.println("Disconnected from server");
}
} catch (IOException ex) { ex.printStackTrace(); }
}
我在编写returnMostRecent(String[])
方法方面做了一次悲惨的尝试,但结果却发现了一个难以理解的混乱,不值得在这里发布。
如何对此数组进行排序并按照优先顺序有效地返回最新文件?
答案 0 :(得分:5)
如果你使用Java8,你可以这样做:
String file = Arrays.stream(filenames)
.filter(s -> s.startsWith("ALFP") && s.endsWith("F.zip"))
.max(getReleaseComparator())
.orElse(null);
其中,发布比较器基于从文件名中提取数字并进行比较
答案 1 :(得分:3)
我没有对此进行测试,但我认为它应该可行。
private String returnMostRecent(String[] fileNames) {
String file = null;
double version = -1;
for(String name : listNames)
{
// skip files that don't match
if (!name.matches("ALFP[0-9]*F.zip"))
continue;
// get digits only
String digits = name.replaceAll("\\D+","");
// format digits to <year>.<version>
String vstr = digits.substring(digits.length-2,digits.length()) + ".";
if (digits.length() < 4)
vstr += "0";
vstr = digits.substring(0, digits.length()-2);
double v = Double.parseDouble(vstr);
if (v > version)
{
version = v;
file = name;
}
}
return file;
}
答案 2 :(得分:2)
我会建议这种方法:
final String[] filesArr = { "1stpage712.txt", "1stpage712.pdf", "1stpage914.pdf", "ALFP1015F.zip", "ALFP1015P.zip", "ALFP716F.zip",
"ALFP716P.zip", "FSFP816F.zip", "FSFP816P.zip" };
// turn the array into a list.
final List<String> filesList = new ArrayList<String>();
// add to the list only the good candidates
for (int i = 0; i < filesArr.length; i++) {
if (filesArr[i].matches("ALFP\\d+F.zip")) {
System.out.println("candidate");
filesList.add(filesArr[i]);
}
}
System.out.println(filesList);
Collections.sort(filesList, new Comparator<String>() {
@Override
public int compare(String o1, String o2) {
final SimpleDateFormat df = new SimpleDateFormat("mmyy");
// get the date of the file
final String dat1 = o1.substring(o1.indexOf("ALFP"), o1.indexOf("ALFP") + 3);
final String dat2 = o2.substring(o2.indexOf("ALFP"), o2.indexOf("ALFP") + 3);
Date date1;
Date date2;
try {
date1 = df.parse(dat1);
date2 = df.parse(dat2);
return date1.compareTo(date2);
} catch (final ParseException e) {
System.out.println("Error parsing date..");
return 0;
}
}
});
// since the sort is made by date chronologically, the 1st element is the oldest and the last element is
// the newest
System.out.println("The file is: " + filesList.get(filesList.size() - 1));
}
答案 3 :(得分:2)
我会建议这个解决方案:
private static String returnMostRecent(String[] fileNames)
{
int lastTwoDigits = Calendar.getInstance().get(Calendar.YEAR) % 100;
int fullFileRel = 0;
int partialFileRel = 0;
for(String myStr : fileNames)
{
if(myStr.startsWith("ALFP"))
{
System.out.println(myStr);
if(myStr.endsWith(""+lastTwoDigits+"F.zip"))
{
String temp = myStr.substring(4,myStr.length()-7);
System.out.println("temp : "+temp);
int releaseNum = Integer.parseInt(temp);
System.out.println("releaseNum : "+releaseNum);
if(releaseNum > fullFileRel)
fullFileRel = releaseNum;
}
if(myStr.endsWith(""+lastTwoDigits+"P.zip"))
{
String temp = myStr.substring(4,myStr.length()-7);
System.out.println("temp : "+temp);
int releaseNum = Integer.parseInt(temp);
System.out.println("releaseNum : "+releaseNum);
if(releaseNum > fullFileRel)
partialFileRel = releaseNum;
}
}
}
System.out.println("full Rel :"+fullFileRel);
System.out.println("partial Rel :"+partialFileRel);
if(fullFileRel > partialFileRel)
return "ALFP"+fullFileRel+""+lastTwoDigits+"F.zip";
else
return "ALFP"+partialFileRel+""+lastTwoDigits+"P.zip";
}
答案 4 :(得分:1)
您可以使用正则表达式并执行类似的操作来解析年份和版本:
<script type="text/javascript">
var PageApiCtor = {
TempProfilePicUrl: '@Url.Action("TempPic", "Member")',
CropUrl: '@Url.Action("CropAndSave", "Member")',
DeletePicUrl: '@Url.Action("DeletePic", "Member")',
NoPicUrl: '@Url.Content("~/Content/images/no-pic.gif")',
LastProfileRef: undefined
};
答案 5 :(得分:1)
这是Java 1.5兼容的解决方案,AlphaNumComparator