public static void main(String[] args) throws Exception {
FileInputStream fin = new FileInputStream(new File("G://demo.txt"));
FileOutputStream fout =new FileOutputStream("G://11.txt");
//InputStreamReader in = new InputStreamReader(fin); ----------------------------------这里注释掉
OutputStreamWriter out = new OutputStreamWriter(fout,"gb2312");
int b;
while((b=fin.read()) != -1){
fout.write(b);
}