首先，不同編碼的文本，是根據文本的前兩個字節來定義其編碼格式的。定義如下：
ANSI： 無格式定義；
Unicode： 前兩個字節為FFFE；
Unicode big endian： 前兩字節為FEFF；
UTF-8： 前兩字節為EFBB；
知道了各種編碼格式的區別，寫代碼就容易了.
- public static String get_charset( File file ) {
- String charset = "GBK";
- byte[] first3Bytes = new byte[3];
- try {
- boolean;
- BufferedInputStream bis = new BufferedInputStream( new FileInputStream( file ) );
- bis.mark( 0 );
- int read = bis.read( first3Bytes, 0, 3 );
- if ( read == -1 ) return charset;
- if ( first3Bytes[0] == (byte) 0xFF && first3Bytes[1] == (byte) 0xFE ) {
- charset = "UTF-16LE";
- checked = true;
- }
- else if ( first3Bytes[0] == (byte) 0xFE && first3Bytes[1] == (byte) 0xFF ) {
- charset = "UTF-16BE";
- checked = true;
- }
- else if ( first3Bytes[0] == (byte) 0xEF && first3Bytes[1] == (byte) 0xBB && first3Bytes[2] == (byte) 0xBF ) {
- charset = "UTF-8";
- checked = true;
- }
- bis.reset();
- if ( !checked ) {
-
- int loc = 0;
-
- while ( (read = bis.read()) != -1 ) {
- loc++;
- if ( read >= 0xF0 ) break;
- if ( 0x80 <= read && read <= 0xBF )
- break;
- if ( 0xC0 <= read && read <= 0xDF ) {
- read = bis.read();
- if ( 0x80 <= read && read <= 0xBF )
-
- continue;
- else break;
- }
- else if ( 0xE0 <= read && read <= 0xEF ) {
- read = bis.read();
- if ( 0x80 <= read && read <= 0xBF ) {
- read = bis.read();
- if ( 0x80 <= read && read <= 0xBF ) {
- charset = "UTF-8";
- break;
- }
- else break;
- }
- else break;
- }
- }
-
- }
-
- bis.close();
- } catch ( Exception e ) {
- e.printStackTrace();
- }
-
- return charset;
- }
From: http://ajava.org/code/I18N/14816.html