btn_ok.setOnClickListener(new OnClickListener() {

                              @Override

                              public void onClick(View v) {

                                        String user = et_user.getText().toString().trim();

                                        String pwd = et_pwd.getText().toString().trim();

                                        if(user.isEmpty()||pwd.isEmpty()){

                                                  Toast.makeText(getApplicationContext(), "不能為空", 200).show();

                                        }else{

                                                  String name="data.txt";

                                                  String content=user+"="+pwd;

                                                  try {

                                                   FileOutputStream fos=openFileOutput(name, MODE_PRIVATE);

                                                   fos.write(content.getBytes());

                                                   fos.close();

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

                                                  } catch (Exception e) {

                                                            // TODO Auto-generated catch block

                                                            e.printStackTrace();

                                                  }

                                        }

                              }

                    });

btn_show.setOnClickListener(new OnClickListener() {

                              @Override

                              public void onClick(View v) {

                                        String name="data.txt";

                                        try {

                                                  FileInputStream fis=openFileInput(name);

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

                                                  //讀取文檔的數據

                                                  String content = br.readLine();

                                                  //拆分字符串

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

                                                  //顯示的數據

                                                  if(!content.isEmpty()){

                                                            et_user.setText(strs[0]);

                                                            et_pwd.setText(strs[1]);

                                                  }

                                        } catch (Exception e) {

                                                  // TODO Auto-generated catch block

                                                  e.printStackTrace();

                                        }          

                              }

                    });