Проверьте это.Это сработало для меня.
LockScreenActivity.java
package com.kns;
import android.app.Activity;
import android.app.ActivityManager;
import android.app.admin.DevicePolicyManager;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class LockScreenActivity extends Activity implements OnClickListener {
private Button lock;
private Button disable;
private Button enable;
static final int RESULT_ENABLE = 1;
DevicePolicyManager deviceManger;
ActivityManager activityManager;
ComponentName compName;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
deviceManger = (DevicePolicyManager)getSystemService(
Context.DEVICE_POLICY_SERVICE);
activityManager = (ActivityManager)getSystemService(
Context.ACTIVITY_SERVICE);
compName = new ComponentName(this, MyAdmin.class);
setContentView(R.layout.main);
lock =(Button)findViewById(R.id.lock);
lock.setOnClickListener(this);
disable = (Button)findViewById(R.id.btnDisable);
enable =(Button)findViewById(R.id.btnEnable);
disable.setOnClickListener(this);
enable.setOnClickListener(this);
}
@Override
public void onClick(View v) {
if(v == lock){
boolean active = deviceManger.isAdminActive(compName);
if (active) {
deviceManger.lockNow();
}
}
if(v == enable){
Intent intent = new Intent(DevicePolicyManager
.ACTION_ADD_DEVICE_ADMIN);
intent.putExtra(DevicePolicyManager.EXTRA_DEVICE_ADMIN,
compName);
intent.putExtra(DevicePolicyManager.EXTRA_ADD_EXPLANATION,
"Additional text explaining why this needs to be added.");
startActivityForResult(intent, RESULT_ENABLE);
}
if(v == disable){
deviceManger.removeActiveAdmin(compName);
updateButtonStates();
}
}
private void updateButtonStates() {
boolean active = deviceManger.isAdminActive(compName);
if (active) {
enable.setEnabled(false);
disable.setEnabled(true);
} else {
enable.setEnabled(true);
disable.setEnabled(false);
}
}
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
switch (requestCode) {
case RESULT_ENABLE:
if (resultCode == Activity.RESULT_OK) {
Log.i("DeviceAdminSample", "Admin enabled!");
} else {
Log.i("DeviceAdminSample", "Admin enable FAILED!");
}
return;
}
super.onActivityResult(requestCode, resultCode, data);
}
}
MyAdmin.java
package com.kns;
import android.app.admin.DeviceAdminReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.widget.Toast;
public class MyAdmin extends DeviceAdminReceiver{
static SharedPreferences getSamplePreferences(Context context) {
return context.getSharedPreferences(
DeviceAdminReceiver.class.getName(), 0);
}
static String PREF_PASSWORD_QUALITY = "password_quality";
static String PREF_PASSWORD_LENGTH = "password_length";
static String PREF_MAX_FAILED_PW = "max_failed_pw";
void showToast(Context context, CharSequence msg) {
Toast.makeText(context, msg, Toast.LENGTH_SHORT).show();
}
@Override
public void onEnabled(Context context, Intent intent) {
showToast(context, "Sample Device Admin: enabled");
}
@Override
public CharSequence onDisableRequested(Context context, Intent intent) {
return "This is an optional message to warn the user about disabling.";
}
@Override
public void onDisabled(Context context, Intent intent) {
showToast(context, "Sample Device Admin: disabled");
}
@Override
public void onPasswordChanged(Context context, Intent intent) {
showToast(context, "Sample Device Admin: pw changed");
}
@Override
public void onPasswordFailed(Context context, Intent intent) {
showToast(context, "Sample Device Admin: pw failed");
}
@Override
public void onPasswordSucceeded(Context context, Intent intent) {
showToast(context, "Sample Device Admin: pw succeeded");
}
}
main.xml
<textview android:layout_width="fill_parent" android:layout_height="wrap_content" android:text="To Lock Screen First Enable it.." android:textsize="15sp"></textview>
<button android:id="@+id/lock" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Lock The Phone"></button>
<button android:id="@+id/btnEnable" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Enable"></button>
<button android:id="@+id/btnDisable" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Disable"></button></linearlayout>
icies.xml
<?xml version="1.0" encoding="utf-8"?>
<device-admin xmlns:android="http://schemas.android.com/apk/res/android">
<uses-policies>
<limit-password>
<watch-login>
<reset-password>
<force-lock>
<wipe-data>
</wipe-data></force-lock></reset-password></watch-login></limit-password></uses-policies>
</device-admin>
Этот файл policy.xml может находиться либо в макете, либо в папке xml.Вам нужно позаботиться только о теге метаданных в файле Androidmanifest .
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.kns" android:versioncode="1" android:versionname="1.0">
<uses-sdk android:minsdkversion="8">
<application android:icon="@drawable/icon" android:label="@string/app_name">
<activity android:name=".LockScreenActivity" android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN">
<category android:name="android.intent.category.LAUNCHER">
</category></action></intent-filter>
</activity>
<receiver android:name=".MyAdmin" android:permission="android.permission.BIND_DEVICE_ADMIN">
<meta-data android:name="android.app.device_admin" android:resource="@layout/policies">
<intent-filter>
<action android:name="android.app.action.DEVICE_ADMIN_ENABLED">
</action></intent-filter>
</meta-data></receiver>
</application>
</uses-sdk></manifest>
Перед блокировкой экрана необходимо включить администраторРазрешение
Тогда вы получите это ..
После включения вы заблокируете экран .. вот так
