Android installed password application to force the start of technology

Foreword

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What is the password?

In the dial pad input *#*#<code>#*#*After, APP can monitor these inputs, and then do the appropriate action, such as starting applications, is not it a little show.

The following operating facie this show is how to achieve.

Results preview

Source

DialtactsActivity#showDialpadFragment

There are DialtactsActivity showDialpadFragment method for loading a display dial, so showDialpadFragment looks from the entrance, Android P based on the analysis.

private void showDialpadFragment(boolean animate) {
  //……
  final FragmentTransaction ft = getFragmentManager().beginTransaction();
  if (dialpadFragment == null) {
    dialpadFragment = new DialpadFragment();
    ft.add(R.id.dialtacts_container, dialpadFragment, TAG_DIALPAD_FRAGMENT);
  } else {
    ft.show(dialpadFragment);
  }
  //……
}

具体实现在 DialpapFragment 中，看到 DialpapFragment 实现了 TextWatcher，TextWatcher 有 3 个重要方法，分别为：beforeTextChanged，onTextChanged 和 afterTextChanged，重点看 afterTextChanged 方法。

DialpadFragment#afterTextChanged

public class DialpadFragment extends Fragment
        implements View.OnClickListener,
        View.OnLongClickListener,
        View.OnKeyListener,
        AdapterView.OnItemClickListener,
        TextWatcher,
        PopupMenu.OnMenuItemClickListener,
        DialpadKeyButton.OnPressedListener {
    //……
    @Override
    public void afterTextChanged(Editable input) {
        // When DTMF dialpad buttons are being pressed, we delay SpecialCharSequenceMgr sequence,
        // since some of SpecialCharSequenceMgr's behavior is too abrupt for the "touch-down"
        // behavior.
        if (!digitsFilledByIntent
                && SpecialCharSequenceMgr.handleChars(getActivity(), input.toString(), digits)) {
            // A special sequence was entered, clear the digits
            digits.getText().clear();
        }

        if (isDigitsEmpty()) {
            digitsFilledByIntent = false;
            digits.setCursorVisible(false);
        }

        if (dialpadQueryListener != null) {
            dialpadQueryListener.onDialpadQueryChanged(digits.getText().toString());
        }

        updateDeleteButtonEnabledState();
    }
    //……
}

这里调用了 SpecialCharSequenceMgr 辅助工具类的 handleChars 方法，看这个方法。

SpecialCharSequenceMgr#handleChars

public static boolean handleChars(Context context, String input, EditText textField) {
  // get rid of the separators so that the string gets parsed correctly
  String dialString = PhoneNumberUtils.stripSeparators(input);
  if (handleDeviceIdDisplay(context, dialString)
      || handleRegulatoryInfoDisplay(context, dialString)
      || handlePinEntry(context, dialString)
      || handleAdnEntry(context, dialString, textField)
      || handleSecretCode(context, dialString)) {
    return true;
  }
  if (MotorolaUtils.handleSpecialCharSequence(context, input)) {
    return true;
  }
  return false;
}

handleChars 方法中，会对各种特殊的 secret code 进行匹配处理，这里我们看 handleSecretCode。

SpecialCharSequenceMgr#handleSecretCode

static boolean handleSecretCode(Context context, String input) {
  // Secret code specific to OEMs should be handled first.
  if (TranssionUtils.isTranssionSecretCode(input)) {
    TranssionUtils.handleTranssionSecretCode(context, input);
    return true;
  }
  // Secret codes are accessed by dialing *#*#<code>#*#* or "*#<code_starting_with_number>#"
  if (input.length() > 8 && input.startsWith("*#*#") && input.endsWith("#*#*")) {
    String secretCode = input.substring(4, input.length() - 4);
    TelephonyManagerCompat.handleSecretCode(context, secretCode);
    return true;
  }
  return false;
}

再看下 TelephonyManagerCompat.handleSecretCode 方法。

TelephonyManagerCompat#handleSecretCode

public static void handleSecretCode(Context context, String secretCode) {
  // Must use system service on O+ to avoid using broadcasts, which are not allowed on O+.
  if (BuildCompat.isAtLeastO()) {
    if (!TelecomUtil.isDefaultDialer(context)) {
      LogUtil.e(
          "TelephonyManagerCompat.handleSecretCode",
          "not default dialer, cannot send special code");
      return;
    }
    context.getSystemService(TelephonyManager.class).sendDialerSpecialCode(secretCode);
  } else {
    // System service call is not supported pre-O, so must use a broadcast for N-.
    Intent intent =
        new Intent(SECRET_CODE_ACTION, Uri.parse("android_secret_code://" + secretCode));
    context.sendBroadcast(intent);
  }
}

可以看到在拨号中接收到*#*#<code>#*#* 这样的指令时，程序会对外发送广播，这就意味着我们能够接收这个广播然后可以做我们想做的事情。

接下来我们看看这个接受广播代码是怎么写。

应用

首先在 AndroidManifest 文件中注册广播接收器。

<receiver
    android:name=".SecretCodeReceiver">
    <intent-filter>
        <action android:name="android.provider.Telephony.SECRET_CODE" />
        <data android:scheme="android_secret_code" android:host="1010"  />
    </intent-filter>
</receiver>

接收广播，启动应用。

public class SecretCodeReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        if (intent != null && SECRET_CODE_ACTION.equals(intent.getAction())){
            Intent i = new Intent(Intent.ACTION_MAIN);
            i.setClass(context, MainActivity.class);
            i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            context.startActivity(i);
        }
    }
}

So long as the input in the dialing *#*#1010#*#*will be able to launch the corresponding application, OK, received power.

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