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问题:

I trying to change NFC settings (on/off) programmatically on Android 2.3.3.

On the phone, under the "Wireless & network settings",
you can choose to set whether you want to use NFC to read and exchange tags or not.

So I would like to toggle this setting in my application.
But I can't seem to find an api for this.

I'm looking for some code that would probably look like this:

WifiManager wifi = (WifiManager) context.getSystemService(Context.WIFI_SERVICE);
wifi.setWifiEnabled( on/off );

回答1:

You can not turn it on/off manually but you can send the user to the preferences if it is off:

    if (!nfcForegroundUtil.getNfc().isEnabled())
    {
        Toast.makeText(getApplicationContext(), "Please activate NFC and press Back to return to the application!", Toast.LENGTH_LONG).show();
        startActivity(new Intent(android.provider.Settings.ACTION_WIRELESS_SETTINGS));
    }

Method getNfc() just returns the nfcadapter:

nfc = NfcAdapter.getDefaultAdapter(activity.getApplicationContext());

回答2:

It's not possible programatically without rooting device. But you can start NFC Settings Activity by intent action Settings.ACTION_NFC_SETTINGS for api level 16 and above. For api < 16 use Settings.ACTION_WIRELESS_SETTINGS

Previous selected answer suggests to use WIFI_SETTINGS but we can directly move to NFC_SETTINGS

Here's the example :

android.nfc.NfcAdapter mNfcAdapter= android.nfc.NfcAdapter.getDefaultAdapter(v.getContext());

            if (!mNfcAdapter.isEnabled()) {

                AlertDialog.Builder alertbox = new AlertDialog.Builder(v.getContext());
                alertbox.setTitle("Info");
                alertbox.setMessage(getString(R.string.msg_nfcon));
                alertbox.setPositiveButton("Turn On", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                            Intent intent = new Intent(Settings.ACTION_NFC_SETTINGS);
                            startActivity(intent);
                        } else {
                            Intent intent = new Intent(Settings.ACTION_WIRELESS_SETTINGS);
                            startActivity(intent);
                        }
                    }
                });
                alertbox.setNegativeButton("Close", new DialogInterface.OnClickListener() {

                    @Override
                    public void onClick(DialogInterface dialog, int which) {

                    }
                });
                alertbox.show();

            }

回答3:

if you want to do it programmatically, apperently this Q holds the answer:

How can I enable NFC reader via API?

Edit

it didn't hold the answer, but it held the key to the answer, on which I based my code I answered with in the Q.

I will paste it here as well in case anyone's interested.

I got it working through reflection

This code works on API 15, haven't checked it against other verions yet

public boolean changeNfcEnabled(Context context, boolean enabled) {
    // Turn NFC on/off
    final boolean desiredState = enabled;
    mNfcAdapter = NfcAdapter.getDefaultAdapter(context);

    if (mNfcAdapter == null) {
        // NFC is not supported
        return false;
    }

    new Thread("toggleNFC") {
        public void run() {
            Log.d(TAG, "Setting NFC enabled state to: " + desiredState);
            boolean success = false;
            Class<?> NfcManagerClass;
            Method setNfcEnabled, setNfcDisabled;
            boolean Nfc;
            if (desiredState) {
                try {
                    NfcManagerClass = Class.forName(mNfcAdapter.getClass().getName());
                    setNfcEnabled   = NfcManagerClass.getDeclaredMethod("enable");
                    setNfcEnabled.setAccessible(true);
                    Nfc             = (Boolean) setNfcEnabled.invoke(mNfcAdapter);
                    success         = Nfc;
                } catch (ClassNotFoundException e) {
                } catch (NoSuchMethodException e) {
                } catch (IllegalArgumentException e) {
                } catch (IllegalAccessException e) {
                } catch (InvocationTargetException e) {
                }
            } else {
                try {
                    NfcManagerClass = Class.forName(mNfcAdapter.getClass().getName());
                    setNfcDisabled  = NfcManagerClass.getDeclaredMethod("disable");
                    setNfcDisabled.setAccessible(true);
                    Nfc             = (Boolean) setNfcDisabled.invoke(mNfcAdapter);
                    success         = Nfc;
                } catch (ClassNotFoundException e) {
                } catch (NoSuchMethodException e) {
                } catch (IllegalArgumentException e) {
                } catch (IllegalAccessException e) {
                } catch (InvocationTargetException e) {
                }
            }
            if (success) {
                Log.d(TAG, "Successfully changed NFC enabled state to "+ desiredState);
            } else {
                Log.w(TAG, "Error setting NFC enabled state to "+ desiredState);
            }
        }
    }.start();
    return false;
}//end method

This requires 2 permissions though, put them in the manifest:

 <!-- change NFC status toggle -->
    <uses-permission android:name="android.permission.NFC" />
    <uses-permission android:name="android.permission.WRITE_SECURE_SETTINGS" />

The NFC button's state switches accordingly when the code is used, so there are no issues when doing it manually in the seetings menu.

To clarify: This code doesn't work on normal devices. There are ways around, but at least it requires root.