File file = new File(path);
InputStream in= new java.io.FileInputStream(file);
byte[] b = new byte[3];
in.read(b);
in.close();
if (b[0] == -17 && b[1] == -69 && b[2] == -65)
System.out.println(file.getName() + ":编码为UTF-8");
else
System.out.println(file.getName() + ":可能是GBK,也可能是其他编码");