Java自动检测文件编码（字符集）

// 使用之前请调用getAllDetectableCharsets()检查是否满足要求，中文仅有{gb18030, big5,utf-*}
import com.ibm.icu.text.CharsetDetector;
import com.ibm.icu.text.CharsetMatch;

static HashSet<String> getWhiteList(String fileName) {
        if (fileName == null) {
            return null;
        }
        HashSet<String> rs = null;
        InputStreamReader isr = null;
        BufferedReader br = null;
        try {
            FileInputStream fis = new FileInputStream(fileName);
            BufferedInputStream bis = new BufferedInputStream(fis);// markSupported
            CharsetMatch charsetMatch = new CharsetDetector().setText(bis).detect();
            if (charsetMatch != null) {
                isr = new InputStreamReader(bis, charsetMatch.getName());
                System.out.println("Open '" + fileName + " ' with charset: " + charsetMatch.getName());
            } else {
                isr = new InputStreamReader(bis);
                System.out.println(
                        "Open '" + fileName + " ' with charset( default, because no charset is detected by IBM.ICU4J): "
                                + isr.getEncoding());
            }
            br = new BufferedReader(isr);
            String line = null;
            rs = new HashSet<String>();
            while ((line = br.readLine()) != null) {
                rs.add(line);
            }
        } catch (FileNotFoundException e) {
            System.out.println("WARNING: File '" + fileName + "' is not exist.");
        } catch (IOException e) {
            System.out.println("WARNING: IOException occured when read Whitelist.");
        } finally {
            try {
                if (br != null) {
                    br.close();
                }
            } catch (IOException e) {
                System.out.println("WARNING: IOException occured when close BufferedReader.");
            }
        }
        return rs;
    }