檔案編碼辨識工具

public class test {
   
    /**
     * byte陣列轉換成16進制字串
     *
     * @param src
     * @return
     */
    public static String bytesToHexString(byte[] src) {
       StringBuilder stringBuilder = new StringBuilder();
       if (src == null || src.length <= 0) {
           return null;
       }
       for (int i = 0; i < src.length; i++) {
           int v = src[i] & 0xFF;
           String hv = Integer.toHexString(v);
           if (hv.length() < 2) {
              stringBuilder.append(0);
           }
           stringBuilder.append(hv);
       }
       return stringBuilder.toString();
    }

    /**
     * 根據檔流讀取圖片檔真實類型
     *
     * @param is
     * @return
     */

    public static String getTypeByStream(FileInputStream is) {
       byte[] b = new byte[4];
       try {
           is.read(b, 0, b.length);
       } catch (IOException e) {
           e.printStackTrace();
       }
       String type = bytesToHexString(b).toUpperCase();
       if (type.contains("FFD8FF")) {
           return "jpg";
       } else if (type.contains("89504E47")) {
           return "png";
       } else if (type.contains("47494638")) {
           return "gif";
       } else if (type.contains("49492A00")) {
           return "tif";
       } else if (type.contains("424D")) {
           return "bmp";
       } else if (type.contains("494433")) {
           return "mp3";
       }
       return type;
    }

    public static void main(String[] args) throws Exception {
       String src = "2NE1";
       FileInputStream is = new FileInputStream(src);
       String type = getTypeByStream(is);
       System.out.println(type);
    }