File file=new File(Environment.getExternalStorageDirectory(), name);

                  try {

                     FileOutputStream  fos=new FileOutputStream(file);

                     fos.write(content.getBytes());

                     fos.close();

                       Toast.makeText(getApplicationContext(),"保存成功", 200).show();

                  }catch (Exception e) {

                       Toast.makeText(getApplicationContext(),"保存失败", 200).show();

                      e.printStackTrace();

                  }

File file = new File(Environment.getExternalStorageDirectory(), name);      

              try {

                  FileInputStream fis= new FileInputStream(file);

                  BufferedReader br =new BufferedReader(new InputStreamReader(fis));

                  //读取文档的数据

                  String content =br.readLine();

                  //拆分字符串

                  String [] str =content.split("=");

               //显示数据

                  if(!content.isEmpty()){

                     et_name.setText(str[0]);

                     et_password.setText(str[1]);

                  }

              } catch (Exception e) {               

                  e.printStackTrace();

              }            

           }

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE”/>

<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>