Get filename as UTF-8? (ä,ü,ö … is always '?&#

问题:

I have to read the name of some files and put them in a list as a string. Its not so hard I just have some Problems with some characters like ä,ö,ü ... they are always as a '?' in my string.

Whats the Problem? Well the encoding. Ok this should be easy... thats what i thought. So I tried to use functions like:

new String(insert.getBytes("UTF-8") or new String(insert.getBytes("ISO-8859-1"), "UTF-8") because the most of the files are ISO-8859-1

Its not helping. This is my code:

...
File[] fileList = dir.listFiles();
String insert;
for(File f : fileList) {
...
insert=f.getName().substring(0,f.getName().length()-4);
                insert=insert.charAt(0)+insert.substring(1,insert.length()).toLowerCase().replaceFirst("([0-9]*(_s?(i)?(_dat)?)*$)", "").replaceFirst("_", " ");
...
System.out.println("test UTF8: " + new String(insert.getBytes("UTF-8"))); //not helping
System.out.println("test ISO , UTF8: " + new String(insert.getBytes("ISO-8859-1"), "UTF-8")); //not helping
...
names.add(insert);
}

At the end there are a lot of strings with '?' characters in my list. How to fix the problem? And whats the best way if there are not only ISO-8859-1 files? (lets say there are a lot of unknown encoded files)

Thank You!

回答1:

Given the extended comments back and forth under the question, it now looks like this is either a font problem or (perhaps more likely) a filename encoding problem.

I asked Lissy to run the following command to let us figure out what the problem is. If she is sure that the filename contain "ä" in them, but that character does not appear when she ls the filename, then this command will tell us whether this is a font or encoding problem.

touch filenäme
ls filen*me

If this shows "filenäme" in the output of ls then we know the problem is with the creation/copy of the files onto this system. This could happen if the program which created the files didn't realize what the filesystem encoding was or was too stupid to do the right thing. The convmv program will probably be the best way to fix this.

convmv -f ENCODING -t utf8 -r .

The question is what is the proper encoding. Possibilities include UTF-16, cp850, or perhaps iso8859-1. convmv --list will show you the list of currently known (to your system) encodings. Since the listed command above only shows you what it might do, it is safe to run several times with different encodings until you find one which works for all files.

If this is a font problem, we'll have to look into that

回答2:

Unexpected question marks, spalts, etc in a String are a sign that something somewhere doesn't recognize a particular character when converting from one character set to another.

In your case, the problem could be occurring in a couple of places:

• It could be occurring when your Java program is reading the file names from the directory (in the dir.listFiles() call).

• It could be happening when you print the characters to the console stream.

In either case, the root cause is most likely a mismatch between what Java thinks the locale settings should be and the settings that the operating system and/or command shell are using.

As an experiment, try to list a directory containing the problematic file names from the command line. Do you see question marks or other splats there?

A second experiment to perform is to modify your Java program to dump one of the problem Strings as a sequence of numbers representing the character codes for each of the characters. Do you see the character codes for an ASCII / Unicode '?'.

回答3:

The encoding of the content of the file name has nothing to do with the encoding of the file name itself.

You should get correct results from System.out.println(insert)

If you don't, it means that the shell has a different character encoding that the default character encoding for your system (this rarely happens; it would usually be the result of an explicit command to switch encodings in the shell).

If the file names are displayed correctly when you list the directory in the shell, I would expect them to be displayed correctly without specifying an encoding in your Java program.

---

If the shell is incapable of displaying the character (it is substituting the replacement character 0xFFFD (�) for these unprintable characters), there's nothing you can do from your Java application to change that. You need to change the terminal character encoding, install the right fonts, etc.; that is a operating system issue, not a Java issue.

At the same time, even if your terminal can't display the correct results, the Java program should be handling the character encodings correctly without your intervention.

The library behind the File API is figuring out the correct character encoding for your system and doing the necessary decoding into characters. Likewise, the database driver should negotiate with the database to determine the correct encoding, and do any necessary encoding into bytes on behalf of your application.

回答4:

In a comment you wrote:

@mdrg: well, theres a Problem. I have to read the name of the files and then put them into a database. And there are a lot of '?' , that shouldnt be... – Lissy 27 mins ago

My guess is that the column you're inserting the filenames into specifies US-ASCII as the encoding and replaces characters outside that range with a replacement character, which in your case is the question mark.

So you have to find out the encoding for the column in your database table where you store the filenames. Various products have various syntaxes for retrieving that information.

回答5:

In Java 1.6 you can use System.console() instead of System.out.println() to display accentuated characters to console.

public class Test {
  public static void main(String args[]){
   String s = "caractères français :  à é \u00e9"; // Unicode for "é"
   System.console().writer().println(s);
  }
}

and the output is

C:\temp>java Test
caractères français :  à é é