启动应用程序时弹出 Android 默认锁定屏幕

Question

一些应用程序，如 CRED，在启动应用程序时显示 Android 默认锁定屏幕。进入锁屏后pin/fingerprint，我们就可以进入app了。

那么如何弹出用户可以输入他们的锁屏图案的屏幕/pin/fingerprint?

我想 Android 中有一些内置的 class/framework 可以这样做，但我找不到。

Answer 1

Call createConfirmDeviceCredentialIntent() on the KeyguardManager system service。 returns 一个 Intent 可以与 startActivityForResult() 一起使用。如果您在 onActivityResult() 中获得 RESULT_OK，则用户已通过身份验证，可以安全地继续。

例如，这个 activity 有一个触发上述流程的操作栏项目：

/***
 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 profiled in this book）

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