判断编码问题

自己写了一个（第一个），然后客户提供了一个，均分享。

public String GetCharset(File file) {
		String charset = "SJIS";
		byte[] first3Bytes = new byte[3];
		try {
			boolean checked = false;
			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;
	}

第二个：

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.UnsupportedEncodingException;

import org.mozilla.universalchardet.UniversalDetector;

public class EncodingTest {

    public static void main(String[] args) throws UnsupportedEncodingException {
        String sourceFilename = "source.txt";
        FileInputStream fis= null;
        try {
            fis =   new FileInputStream(sourceFilename);
        } catch (FileNotFoundException e1) {
            e1.printStackTrace();
            return;
        }

        UniversalDetector detector = new UniversalDetector(null);
        try {
            while (true) {
                byte[] bytes = new byte[1024];
                int nread;
                nread = fis.read(bytes);
                if(nread <= 0){
                    break;
                }
                
                detector.handleData(bytes, 0, nread);
                
                if(detector.isDone() == true){
                    break;
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
            return;
        }

        detector.dataEnd();
        
        if(fis != null){
            try {
                fis.close();
            } catch (IOException e) {
                e.printStackTrace();
                return;
            }
        }

        String encoding = detector.getDetectedCharset();
        System.out.println("Encoding = " + encoding);
    }

}