Java:检测csv或txt文件的定界符 [英] Java: Detect the delimiter of a csv or txt file
问题描述
我看到这个问题已经被问过好几次了,但是他们使用的是其他语言,我无法理解答案.
I saw that this question was already asked several times but they're on other language and I can't get a grasp on the answers.
我正在通过套接字接收.csv或.txt文件.有什么方法可以检测CSV或TXT文件中一行的定界符或分隔符"?
I am receiving a .csv or .txt file through a socket. Is there any way I can detect the delimiter or "splitter" of a line in the CSV or TXT file?
这是处理文件写入的服务器代码,
This is the server code that handles the file writing,
try{
final ServerSocket server = new ServerSocket(8998);
socket = server.accept();
File sdcard = Environment.getExternalStorageDirectory();
File myFile = new File(sdcard,"TestReceived"+curDate+".csv");
final BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream()));
final PrintWriter pw = new PrintWriter(new FileWriter(myFile));
String line;
String[] wordsarray;
int bc = 0;
int dc = 0;
int pq = 0;
int rq = 0;
int id = 0;
line = br.readLine();
wordsarray = line.split(",");
for (int x = 0; x<wordsarray.length; x++){
switch(wordsarray[x]){
case "COLUMN NAME A": id = x;
break;
case "COLUMN NAME B": bc = x;
break;
case "COLUMN NAME C": dc = x;
break;
case "COLUMN NAME D": pq = x;
break;
case "COLUMN NAME E": rq = x;
break;
}
}
pw.println(wordsarray[dc]+"\t"+wordsarray[rq]+"\t"+wordsarray[pq]+"\t"+wordsarray[bc]+"\t"+wordsarray[id]);
for (line = br.readLine(); line != null; line = br.readLine()) {
wordsarray = line.split(",");
pw.println(wordsarray[dc]+"\t"+wordsarray[rq]+"\t"+wordsarray[pq]+"\t"+wordsarray[bc]+"\t"+wordsarray[id]);
}
pw.flush();
pw.close();
br.close();
socket.close();
server.close();
}
catch (Exception e){
e.printStackTrace();
}
如果我在 line.split();
上加上逗号,并且文件具有不同的定界符,则会产生重复的行,我什至不知道为什么会发生这种情况
If I put a comma on line.split();
and the file has a different delimiter, it produces repeated lines and I don't even know why is that happening
COLUMN NAME A COLUMN NAME B COLUMN NAME C COLUMN NAME D COLUMN NAME E COLUMN NAME A COLUMN NAME B COLUMN NAME C COLUMN NAME D COLUMN NAME E COLUMN NAME A COLUMN NAME B COLUMN NAME C COLUMN NAME D COLUMN NAME E COLUMN NAME A COLUMN NAME B COLUMN NAME C COLUMN NAME D COLUMN NAME E COLUMN NAME A COLUMN NAME B COLUMN NAME C COLUMN NAME D COLUMN NAME E COLUMN NAME A COLUMN NAME B COLUMN NAME C COLUMN NAME D COLUMN NAME E
但是,如果文件具有匹配的逗号分隔符,则会产生正确的输出.
But If the file has a matching delimiter of comma it produces just the right output.
COLUMN NAME A COLUMN NAME B COLUMN NAME C COLUMN NAME D COLUMN NAME E
有什么方法可以自动检测文件的分隔符,这样我就不必担心文件使用的是哪个分隔符?还是有更好的解决方案?
Is there any way I can automatically detect the delimiter of a file so I won't have to worry which delimiter the file is using? Or is there a better solution for it?
推荐答案
使用 mark(...)
,阅读第一个
Use a BufferedReader
, place a mark(...)
, read the first line. If that line contains a \t
tab character, then your file is tab-separated, otherwise assume that it is comma-separated.
然后使用CSV/TSV解析器解析文件,例如 Apache Commons CSV .
Then parse the file using a CSV/TSV parser, e.g. Apache Commons CSV.
try (BufferedReader in = Files.newBufferedReader(Paths.get(filename))) {
in.mark(1024);
String line = in.readLine();
if (line == null)
throw new IOException("File is empty: " + filename);
CSVFormat fileFormat = (line.indexOf('\t') != -1 ? CSVFormat.TDF
: CSVFormat.RFC4180)
.withHeader();
in.reset();
for (CSVRecord record : fileFormat.parse(in)) {
String lastName = record.get("Last Name");
String firstName = record.get("First Name");
...
}
}
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