Android Studio Code for Lock Screen
Pre-requisites: Eclipse IDE, Android SDK
Step 1: Create Android project
Launch Eclipse IDE and create a new Android application project called AndroidLockScreenDemo with package name com.example
Step 2: Create Activity class
Create a new Activity class called MyLockScreenActivity within the above package and add the following code!
MyLockScreenActivity.java
package com.example;import android.app.Activity;import android.app.admin.DevicePolicyManager;import android.content.ComponentName;import android.content.Context;import android.content.Intent;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.Toast;public class MyLockScreenActivity extends Activity implements OnClickListener { private static final int ADMIN_INTENT = 15; private static final String description = "Sample Administrator description"; private DevicePolicyManager mDevicePolicyManager; private ComponentName mComponentName; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_lock); mDevicePolicyManager = (DevicePolicyManager)getSystemService( Context.DEVICE_POLICY_SERVICE); mComponentName = new ComponentName(this, MyAdminReceiver.class); Button btnEnableAdmin = (Button) findViewById(R.id.btnEnable); Button btnDisableAdmin = (Button) findViewById(R.id.btnDisable); Button btnLock = (Button) findViewById(R.id.btnLock); btnEnableAdmin.setOnClickListener(this); btnDisableAdmin.setOnClickListener(this); btnLock.setOnClickListener(this); } @Override public void onClick(View v) { switch (v.getId()) { case R.id.btnEnable: Intent intent = new Intent(DevicePolicyManager.ACTION_ADD_DEVICE_ADMIN); intent.putExtra(DevicePolicyManager.EXTRA_DEVICE_ADMIN, mComponentName); intent.putExtra(DevicePolicyManager.EXTRA_ADD_EXPLANATION,description); startActivityForResult(intent, ADMIN_INTENT); break; case R.id.btnDisable: mDevicePolicyManager.removeActiveAdmin(mComponentName); Toast.makeText(getApplicationContext(), "Admin registration removed", Toast.LENGTH_SHORT).show(); break; case R.id.btnLock: boolean isAdmin = mDevicePolicyManager.isAdminActive(mComponentName); if (isAdmin) { mDevicePolicyManager.lockNow(); }else{ Toast.makeText(getApplicationContext(), "Not Registered as admin", Toast.LENGTH_SHORT).show(); } break; } } @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) { if (requestCode == ADMIN_INTENT) { if (resultCode == RESULT_OK) { Toast.makeText(getApplicationContext(), "Registered As Admin", Toast.LENGTH_SHORT).show(); }else{ Toast.makeText(getApplicationContext(), "Failed to register as Admin", Toast.LENGTH_SHORT).show(); } } }} |
activity_lock.xml
android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MyLockScreenActivity"> <TextView android:id="@+id/txt1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/hello_world"/> <Button android:id="@+id/btnEnable" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Enable" android:layout_below="@+id/txt1"/> <Button android:id="@+id/btnDisable" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Disable" android:layout_below="@+id/btnEnable"/> <Button android:id="@+id/btnLock" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Lock" android:layout_below="@+id/btnDisable"/></RelativeLayout> |
Step 3: Add lock policy and create receiver
Create a new folder called xml inside the project and add an XML file for exercising admin rights called admin.xml containing the following code!
<uses-policies> <force-lock /> </uses-policies></device-admin> |
You also need to create an empty Receiver class that will extend the DeviceAdminReceiver. I am going to name my class as MyAdminReceiver.
MyAdminReceiver.java
package com.example;import android.app.admin.DeviceAdminReceiver;public class MyAdminReceiver extends DeviceAdminReceiver{} |
In this case, one needs to update the AndroidManifest.xml file and add the Receiver entry as follows!
<?xml version="1.0" encoding="utf-8"?> package="com.example" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="8" android:targetSdkVersion="18" /> <application android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <activity android:name="com.example.MyLockScreenActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> <receiver android:name="MyAdminReceiver" android:permission="android.permission.BIND_DEVICE_ADMIN"> <meta-data android:name="android.app.device_admin" android:resource="@xml/admin"/> <intent-filter> <action android:name="android.app.action.DEVICE_ADMIN_ENABLED" /> </intent-filter> </receiver> </application></manifest> |
Save all changes and make sure no errors are present. Finally, run the application on an Android device and you should now be able to lock your screen through code! 
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