启动应用时弹出 Android 默认锁屏

Question

CRED 等一些应用在启动应用时会显示 Android 默认锁定屏幕。输入锁屏密码/指纹后，我们就可以进入应用了。

那么如何弹出这样的屏幕，用户可以在其中输入他们的锁屏图案/pin/指纹？

我猜在 Android 中有一些内置的类/框架可以这样做，但我无法找到。

Answer 1

Call createConfirmDeviceCredentialIntent() on the KeyguardManager system service。这将返回一个Intent，您可以将其与startActivityForResult() 一起使用。如果在onActivityResult() 中得到RESULT_OK，则用户已通过身份验证，可以安全继续。

例如，这个activity有一个触发上述流程的action bar item：

/***
 Copyright (c) 2018 CommonsWare, LLC
 Licensed under the Apache License, Version 2.0 (the "License"); you may not
 use this file except in compliance with the License. You may obtain    a copy
 of the License at http://www.apache.org/licenses/LICENSE-2.0. Unless required
 by applicable law or agreed to in writing, software distributed under the
 License is distributed on an "AS IS" BASIS,    WITHOUT WARRANTIES OR CONDITIONS
 OF ANY KIND, either express or implied. See the License for the specific
 language governing permissions and limitations under the License.

 Covered in detail in the book _The Busy Coder's Guide to Android Development_
 https://commonsware.com/Android
 */

package com.commonsware.android.auth.check;

import android.annotation.TargetApi;
import android.app.Activity;
import android.app.KeyguardManager;
import android.content.Intent;
import android.os.Build;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.ImageView;
import android.widget.Toast;

public class MainActivity extends Activity {
  private static final int REQUEST_CODE=1337;
  private KeyguardManager mgr;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mgr=(KeyguardManager)getSystemService(KEYGUARD_SERVICE);

    ImageView device=findViewById(R.id.device);
    ImageView keyguard=findViewById(R.id.keyguard);

    if (Build.VERSION.SDK_INT>=Build.VERSION_CODES.M) {
      if (mgr.isDeviceSecure()) {
        device.setImageResource(R.drawable.ic_lock_black_24dp);
      }
      else {
        device.setImageResource(R.drawable.ic_lock_open_black_24dp);
      }
    }
    else {
      device.setImageResource(R.drawable.ic_help_black_24dp);
    }

    if (mgr.isKeyguardSecure()) {
      keyguard.setImageResource(R.drawable.ic_lock_black_24dp);
    }
    else {
      keyguard.setImageResource(R.drawable.ic_lock_open_black_24dp);
    }
  }

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    if (Build.VERSION.SDK_INT>=Build.VERSION_CODES.LOLLIPOP) {
      getMenuInflater().inflate(R.menu.actions, menu);
    }

    return super.onCreateOptionsMenu(menu);
  }

  @Override
  public boolean onOptionsItemSelected(MenuItem item) {
    if (item.getItemId()==R.id.auth) {
      authenticate();

      return true;
    }

    return super.onOptionsItemSelected(item);
  }

  @Override
  protected void onActivityResult(int requestCode, int resultCode,
                                  Intent data) {
    if (requestCode==REQUEST_CODE) {
      if (resultCode==RESULT_OK) {
        Toast.makeText(this, "Authenticated!", Toast.LENGTH_SHORT).show();
      }
      else {
        Toast.makeText(this, "WE ARE UNDER ATTACK!", Toast.LENGTH_SHORT).show();
      }
    }
  }

  @TargetApi(Build.VERSION_CODES.LOLLIPOP)
  private void authenticate() {
    Intent i=mgr.createConfirmDeviceCredentialIntent("title", "description");

    if (i==null) {
      Toast.makeText(this, "No authentication required!", Toast.LENGTH_SHORT).show();
    }
    else {
      startActivityForResult(i, REQUEST_CODE);
    }
  }
}

（取自this sample app，this book）