How to know if users entered a wrong passcode (lock screen) in android app

问题

I am working on an Android App in which one of the activity has to be completed if user enter a wrong passcode in android lock screen. For example an email sent if user entered a wrong passcode..

I will appreciate any help. Thanks in advance.

Kshitij

回答1:

The lock screen are running in a total sandbox environment which makes it makes it inaccessible.You can create a different Application acting as the lock screen and disabling the default android version.

回答2:

You can do this by registering your app as Device Administrator.
Add watch-login tag to device admin metadata and then you will be able to handle onPasswordFailed and onPasswordSucceeded events.
create a file named device_admin.xml in your res/xml folder and put these tags inside it:

<?xml version="1.0" encoding="utf-8"?>
<device-admin xmlns:android="http://schemas.android.com/apk/res/android">
    <uses-policies>
        <watch-login />
    </uses-policies>
</device-admin>  

then you need to create a AdminReciever class that extends from DeviceAdminReceiver. inside this class you can handle onPasswordFailed and do what you need if user entered incorrect password. you can see full example here:
Password Enforcer Sample
NOTE
as far as i know, this works only with Password and PIN and Patterns is not supported.

来源：https://stackoverflow.com/questions/7782685/how-to-know-if-users-entered-a-wrong-passcode-lock-screen-in-android-app