在玩android的时候，有时候需要这样的功能，在editText里输入字符，要实时的监控输入的内容，比如 我要获取手机的IMEI号码。最后要输入*#06#就可以获取到了。那这是如何做到呢？或者说Phone是如何实现这个功能的呢？
这主要用到了TextWatcher接口。
public class DialpadFragment extends Fragment
implements View.OnClickListener,
View.OnLongClickListener, View.OnKeyListener,
AdapterView.OnItemClickListener, TextWatcher,
PopupMenu.OnMenuItemClickListener,
DialpadImageButton.OnPressedListener
这个类是拨号界面的类。可以看到它就实现了TextWatcher
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
mWasEmptyBeforeTextChange = TextUtils.isEmpty(s);
}
@Override
public void onTextChanged(CharSequence input, int start, int before, int changeCount) {
if (mWasEmptyBeforeTextChange != TextUtils.isEmpty(input)) {
final Activity activity = getActivity();
if (activity != null) {
activity.invalidateOptionsMenu();
}
}
// DTMF Tones do not need to be played here any longer -
// the DTMF dialer handles that functionality now.
}
@Override
public void afterTextChanged(Editable input) {
// When DTMF dialpad buttons are being pressed, we delay SpecialCharSequencMgr sequence,
// since some of SpecialCharSequenceMgr‘s behavior is too abrupt for the "touch-down"
// behavior.
if (!mDigitsFilledByIntent &&
SpecialCharSequenceMgr.handleChars(getActivity(), input.toString(), mDigits)) {
// A special sequence was entered, clear the digits
mDigits.getText().clear();
}
if (isDigitsEmpty()) {
mDigitsFilledByIntent = false;
mDigits.setCursorVisible(false);
}
updateDialAndDeleteButtonEnabledState();
}
判断输入的内容就是这句SpecialCharSequenceMgr.handleChars(getActivity(), input.toString(), mDigits))
进入了这里
static boolean handleIMEIDisplay(Context context, String input, boolean useSystemWindow) {
if (input.equals(MMI_IMEI_DISPLAY)) {
int subscription = MSimTelephonyManager.getDefault().getPreferredVoiceSubscription();
int phoneType;
if (MSimTelephonyManager.getDefault().isMultiSimEnabled()) {
phoneType = ((MSimTelephonyManager)context.getSystemService(
Context.MSIM_TELEPHONY_SERVICE)).getCurrentPhoneType(subscription);
} else {
phoneType = ((TelephonyManager)context.getSystemService(
Context.TELEPHONY_SERVICE)).getCurrentPhoneType();
}
if (phoneType == TelephonyManager.PHONE_TYPE_GSM) {
showIMEIPanel(context, useSystemWindow);
return true;
} else if (phoneType == TelephonyManager.PHONE_TYPE_CDMA) {
showMEIDPanel(context, useSystemWindow);
return true;
}
}
return false;
}
最后通过
AlertDialog alert = new AlertDialog.Builder(context)
.setTitle(R.string.imei)
.setMessage(imeiStr)
.setPositiveButton(android.R.string.ok, null)
.setCancelable(false)
.show();
显示出对话框了。