String strDistrictName = "fengyuzaitu";

       try { 

            FileOutputStream fos = new FileOutputStream("/storage/sdcard0/Android/data/test.txt"); 

            OutputStreamWriter osw = new OutputStreamWriter(fos, "gb2312"); 

            osw.write(strDistrictName); 

            osw.flush(); 

        } catch (Exception e) { 

            e.printStackTrace(); 

        }