blocks|key|2939156|text|目前还不可能知道这类信息，去年已经有一个问题开始要求它(https://issuetracker.google.com/issues/111315641)。由于Android试图简化开发人员在其应用程序中实现身份验证的路径，BiometricPrompt实现中缺少选项(参见BiometricPrompt实现的Android+)。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2939157|entityMap|0|LINK|mutability|MUTABLE|url|https://issuetracker.google.com/issues/111315641^0|S|1C|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

There is no mean of knowing this type of information for now, an issue had been opened last year to ask for it (<a href="https://issuetracker.google.com/issues/111315641" rel="nofollow noreferrer">https://issuetracker.google.com/issues/111315641</a>). As Android tried to simplify the path for developer to implement authentication in their apps, there is a lack of options in the BiometricPrompt implementation (see the Android document for BiometricPrompt implementation).

blocks|key|2939235|text|在您的情况下，您可以简单地将标题字符串更改为“生物识别身份验证”，以及其他字符串。关于一个例子，请看下面的博客文章。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2939236|您的代码可能如下所示。但我还建议您使用strings.xml资源文件，而不是在代码中对字符串进行硬编码。例如，在将来，您可能需要翻译服务。|offset|length|style|CODE|2939237|biometricPrompt+=+new+BiometricPrompt.Builder(context)
++++++++.setTitle("Biometric+Authentication")
++++++++.setSubtitle("Login+via+biometrics")
++++++++.setDescription("Use+the+Biometrics+Sensor")
++++++++.setNegativeButton("Cancel",+context.getMainExecutor(),
++++++++++++++++new+DialogInterface.OnClickListener()+{
++++++++++++++++++++@Override
++++++++++++++++++++public+void+onClick(DialogInterface+dialogInterface,+int+i)+{
++++++++++++++++++++++++Log.d(TAG,"Cancelled");
++++++++++++++++++++}
++++++++++++++++})
++++++++.build();|code-block|syntax|javascript|2939238|更广泛地说，在API团队决定开发人员是否应该知道用户的生物特征偏好之前，必须评估其对隐私的影响。现在还不清楚为什么开发人员需要这些信息。已经发表了两篇关于强和弱生物特征以及如何实现它们的博客文章(博客一，博客二)。除了这种区别(即强与弱)之外，用户喜欢或最终使用什么形式因素似乎不相关。|BOLD|2939239|entityMap|0|LINK|mutability|MUTABLE|url|https://medium.com/androiddevelopers/migrating-from-fingerprintmanager-to-biometricprompt-4bc5f570dccd|1|https://android-developers.googleblog.com/2019/10/one-biometric-api-over-all-android.html^0|0|J|B|0|0|25|1|27|1|2Q|3|0|2U|3|1|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|10|8|@$D|11|E|12|F|G]]|9|@]|A|$]]|$1|H|3|I|5|J|7|13|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|14|8|@$D|15|E|16|F|O]|$D|17|E|18|F|O]]|9|@$D|19|E|1A|1|1B]|$D|1C|E|1D|1|1E]]|A|$]]|$1|P|3|-4|5|6|7|1F|8|@]|9|@]|A|$]]]|Q|$R|$5|S|T|U|A|$V|W]]|X|$5|S|T|U|A|$V|Y]]]]

In your case you can simply change your title String to "Biometric Authentication", and so with the other Strings. For an example see the blog posts pointed to below.

Your code might look as follows. But I'd also recommend you use the <code>strings.xml</code> resource file instead of hard-coding your Strings in the code. For example, in the future, you may want translation services.

<pre><code>biometricPrompt = new BiometricPrompt.Builder(context)
 .setTitle("Biometric Authentication")
 .setSubtitle("Login via biometrics")
 .setDescription("Use the Biometrics Sensor")
 .setNegativeButton("Cancel", context.getMainExecutor(),
 new DialogInterface.OnClickListener() {
 @Override
 public void onClick(DialogInterface dialogInterface, int i) {
 Log.d(TAG,"Cancelled");
 }
 })
 .build();
</code></pre>

More broadly, the privacy implications must be evaluated before the API team makes a decision whether developers should know a user's biometric preferences. It's really not clear why a developer should need this information. Two blog posts have been published that touch on the subject of Strong vs Weak biometrics and how to implement them (<a href="https://medium.com/androiddevelopers/migrating-from-fingerprintmanager-to-biometricprompt-4bc5f570dccd" rel="nofollow noreferrer">blog one</a>, <a href="https://android-developers.googleblog.com/2019/10/one-biometric-api-over-all-android.html" rel="nofollow noreferrer">blog two</a>). Beyond that distinction (i.e. Strong vs Weak), what form-factors a user prefers or ends up using doesn't seem pertinent.

blocks|key|1388781|text|setAllowedAuthenticators|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1388782|public+BiometricPrompt.Builder+setAllowedAuthenticators+(int+authenticators)|code-block|syntax|javascript|1388783|可选:指定BiometricPrompt可调用的验证器类型以验证用户。可用的身份验证器类型是在身份验证器中定义的，可以通过按位OR组合。默认为：|1388784|用于非密码身份验证的Authenticators#BIOMETRIC_WEAK，或|unordered-list-item|1388785|用于基于密码的身份验证的Authenticators#BIOMETRIC_STRONG。|1388786|如果使用此方法，并且在BiometricPrompt#authenticate(.)时没有任何指定类型的身份验证器可用调用时，将取消身份验证，并使用适当的错误代码调用AuthenticationCallback#onAuthenticationError(int，CharSequence)。|1388787|这个方法应该比setDeviceCredentialAllowed(boolean)更好，如果两者都使用，则重写后者。使用此方法启用设备凭据身份验证(使用Authenticators#DEVICE_CREDENTIAL)将替换提示符上的否定按钮，因此调用setNegativeButton(java.lang.CharSequence、java.util.concurrent.Executor、setNegativeButton)也是错误的。|style|BOLD|1388788|authenticators|1388789|表示提示符可能调用的所有有效身份验证器类型的位字段。值要么是0，要么是BiometricManager.Authenticators.BIOMETRIC_STRONG，BiometricManager.Authenticators.BIOMETRIC_WEAK，和BiometricManager.Authenticators.DEVICE_CREDENTIAL的组合。|blockquote|1388790|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.android.com/reference/android/hardware/biometrics/BiometricPrompt.Builder#setAllowedAuthenticators(int)^0|0|O|0|0|0|0|0|0|0|7|Z|0|0|E|0|0^^$0|@$1|2|3|4|5|6|7|18|8|@]|9|@$A|19|B|1A|1|1B]]|C|$]]|$1|D|3|E|5|F|7|1C|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|1D|8|@]|9|@]|C|$]]|$1|K|3|L|5|M|7|1E|8|@]|9|@]|C|$]]|$1|N|3|O|5|M|7|1F|8|@]|9|@]|C|$]]|$1|P|3|Q|5|6|7|1G|8|@]|9|@]|C|$]]|$1|R|3|S|5|6|7|1H|8|@$A|1I|B|1J|T|U]]|9|@]|C|$]]|$1|V|3|W|5|6|7|1K|8|@$A|1L|B|1M|T|U]]|9|@]|C|$]]|$1|X|3|Y|5|Z|7|1N|8|@]|9|@]|C|$]]|$1|10|3|-4|5|6|7|1O|8|@]|9|@]|C|$]]]|11|$12|$5|13|14|15|C|$16|17]]]]

<a href="https://developer.android.com/reference/android/hardware/biometrics/BiometricPrompt.Builder#setAllowedAuthenticators(int)" rel="nofollow noreferrer">In Android R was added a method called setAllowedAuthenticators</a>

<pre><code>public BiometricPrompt.Builder setAllowedAuthenticators (int authenticators)
</code></pre>

Optional: Specifies the type(s) of authenticators that may be invoked by BiometricPrompt to authenticate the user. Available authenticator types are defined in Authenticators and can be combined via bitwise OR. Defaults to:

<ul>
<li>Authenticators#BIOMETRIC_WEAK for non-crypto authentication, or</li>
<li>Authenticators#BIOMETRIC_STRONG for crypto-based authentication.</li>
</ul>

If this method is used and no authenticator of any of the specified types is available at the time BiometricPrompt#authenticate(...) is called, authentication will be canceled and AuthenticationCallback#onAuthenticationError(int, CharSequence) will be invoked with an appropriate error code.

<hr>

This method should be preferred over setDeviceCredentialAllowed(boolean) and overrides the latter if both are used. Using this method to enable device credential authentication (with Authenticators#DEVICE_CREDENTIAL) will replace the negative button on the prompt, making it an error to also call setNegativeButton(java.lang.CharSequence, java.util.concurrent.Executor, android.content.DialogInterface.OnClickListener).

<hr>

authenticators 

<blockquote>
 A bit field representing all valid authenticator types that may be
 invoked by the prompt. Value is either 0 or a combination of
 BiometricManager.Authenticators.BIOMETRIC_STRONG,
 BiometricManager.Authenticators.BIOMETRIC_WEAK, and
 BiometricManager.Authenticators.DEVICE_CREDENTIAL
</blockquote>

blocks|key|2939263|text|虽然不是一个完美的解决方案，但您可以使用PackageManager+API来确定设备是否具有验证器硬件，例如：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2939264|if+(context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_FACE))
{
}|code-block|syntax|javascript|2939265|我创建了一个助手类，如下所示：|2939266|class+BiometricAuthenticator
{
+public+enum+BiometricType
+{
++FINGERPRINT,
++FACE,+
++IRIS,
++NONE
+}

+public+static+boolean+hasBiometricAuthenticator(Context+context)
+{
++++int+biometry+=+BiometricManager.BIOMETRIC_ERROR_UNSUPPORTED;
++++if+(VERSION.SDK_INT+>=+30)
++++++++biometry+=+BiometricManager.from(context).canAuthenticate(Authenticators.BIOMETRIC_STRONG+%7C+Authenticators.BIOMETRIC_WEAK);
++++else
++++++++biometry+=+BiometricManager.from(context).canAuthenticate();

++++switch+(biometry)
++++{
++++++++case+BiometricManager.BIOMETRIC_ERROR_HW_UNAVAILABLE:
++++++++case+BiometricManager.BIOMETRIC_ERROR_NONE_ENROLLED:
++++++++case+BiometricManager.BIOMETRIC_ERROR_NO_HARDWARE:
+++++++++++++return+(false);
++++++++case+BiometricManager.BIOMETRIC_SUCCESS:
+++++++++++++return+true;
++++}
++++return+(false);
+}

+/**
++*+biometricType()
++*
++*+returns+type+of+biometry+supported
++*/
+public+static+BiometricType+biometricType(Context+context)
+{
++++if+(VERSION.SDK_INT+<+23)
++++++++return+BiometricType.NONE;

++++PackageManager+packageManager+=+context.getPackageManager();

++++//+SDK+29+adds+FACE+and+IRIS+authentication
++++if+(VERSION.SDK_INT+>=+29)
++++{
++++++++if+(packageManager.hasSystemFeature(PackageManager.FEATURE_FACE))
++++++++++++return+BiometricType.FACE;
++++++++if+(packageManager.hasSystemFeature(PackageManager.FEATURE_IRIS))
++++++++++++return+BiometricType.IRIS;
++++++++if+(packageManager.hasSystemFeature(PackageManager.FEATURE_FINGERPRINT))
++++++++++++return+BiometricType.FINGERPRINT;
++++++++return+BiometricType.NONE;
++++}

++++//+SDK+23-28+offer+FINGERPRINT+only
++++return+(packageManager.hasSystemFeature(PackageManager.FEATURE_FINGERPRINT)+?+BiometricType.FINGERPRINT+:+BiometricType.NONE);
+}
}|2939267|这允许您确定是否存在生物鉴别器(hasBiometricAuthenticator)，如果存在，则将身份验证器的类型作为BiometricType枚举返回。|offset|length|style|CODE|2939268|理论上，一个设备可以有多个身份验证器，而biometricType()将返回API30%2B设备上的FACE、IRIS，然后按偏好顺序进行指纹识别。|2939269|希望Google将来能公开更好的API，但这些技巧至少有助于在对话框中获得适当的提示。|2939270|entityMap^0|0|0|0|0|G|P|1O|D|0|K|F|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Y|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|Z|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|10|8|@$M|11|N|12|O|P]|$M|13|N|14|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|6|7|15|8|@$M|16|N|17|O|P]]|9|@]|A|$]]|$1|S|3|T|5|6|7|18|8|@]|9|@]|A|$]]|$1|U|3|-4|5|6|7|19|8|@]|9|@]|A|$]]]|V|$]]

While not a perfect solution, you can use the PackageManager API to determine whether a device has the authenticator hardware, e.g.:
<pre><code>if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_FACE))
{
}
</code></pre>
I've created a helper class as follows:
<pre><code>class BiometricAuthenticator
{
 public enum BiometricType
 {
 FINGERPRINT,
 FACE, 
 IRIS,
 NONE
 }

 public static boolean hasBiometricAuthenticator(Context context)
 {
 int biometry = BiometricManager.BIOMETRIC_ERROR_UNSUPPORTED;
 if (VERSION.SDK_INT &gt;= 30)
 biometry = BiometricManager.from(context).canAuthenticate(Authenticators.BIOMETRIC_STRONG | Authenticators.BIOMETRIC_WEAK);
 else
 biometry = BiometricManager.from(context).canAuthenticate();

 switch (biometry)
 {
 case BiometricManager.BIOMETRIC_ERROR_HW_UNAVAILABLE:
 case BiometricManager.BIOMETRIC_ERROR_NONE_ENROLLED:
 case BiometricManager.BIOMETRIC_ERROR_NO_HARDWARE:
 return (false);
 case BiometricManager.BIOMETRIC_SUCCESS:
 return true;
 }
 return (false);
 }

 /**
 * biometricType()
 *
 * returns type of biometry supported
 */
 public static BiometricType biometricType(Context context)
 {
 if (VERSION.SDK_INT &lt; 23)
 return BiometricType.NONE;

 PackageManager packageManager = context.getPackageManager();

 // SDK 29 adds FACE and IRIS authentication
 if (VERSION.SDK_INT &gt;= 29)
 {
 if (packageManager.hasSystemFeature(PackageManager.FEATURE_FACE))
 return BiometricType.FACE;
 if (packageManager.hasSystemFeature(PackageManager.FEATURE_IRIS))
 return BiometricType.IRIS;
 if (packageManager.hasSystemFeature(PackageManager.FEATURE_FINGERPRINT))
 return BiometricType.FINGERPRINT;
 return BiometricType.NONE;
 }

 // SDK 23-28 offer FINGERPRINT only
 return (packageManager.hasSystemFeature(PackageManager.FEATURE_FINGERPRINT) ? BiometricType.FINGERPRINT : BiometricType.NONE);
 }
}
</code></pre>
This allows you to determine if a biometric authenticator is present (<code>hasBiometricAuthenticator</code>), and if so, return the type of authenticator as a <code>BiometricType</code> enum.
A device could theoretically have multiple authenticators, and <code>biometricType()</code> will return FACE, IRIS, then FINGERPRINT in that order of preference on API30+ devices.
Hopefully Google will expose better API in the future, but these tricks will at least help get appropriate prompts on the dialog

As we all know, from android 9.0, android introduced BiometricPrompt Api to provide standard authentication experience across growing range of biometric sensors (E.g Fingerprint,Face ID etc).

Now with this new BiometricPrompt Api user can get authenticated via fingerprint, face scanner or iris scanned (depend on their biometric preference). BiometricPrompt api will take care of this and it will notify us via various callbacks.

Below is my code to display Biometric Prompt.

<pre><code> biometricPrompt = new BiometricPrompt.Builder(context)
 .setTitle("FingerPrint Authentication")
 .setSubtitle("Login via Fingerprint")
 .setDescription("Touch Fingerprint Sensor")
 .setNegativeButton("Cancel", context.getMainExecutor(),
 new DialogInterface.OnClickListener() {
 @Override
 public void onClick(DialogInterface dialogInterface, int i) {
 Log.d(TAG,"Cancelled");
 }
 })
 .build();
</code></pre>

Now if you see my code, i am setting title as a Fingerprint Authentication. Now in device setting, if user had set a Biometric Preference as a Face ID instead of FingerPrint then this biometricPrompt will authenticate user via faceID and fingerprint sensor wont work even if user keep touching sensor. This would create confusion as Biometric title is saying that "Fingerprint authentication" and user is actually getting authenticated via faceID

Is there any way by which we can know what Biometric preference user has selected (e.g Fingerprint or FaceID)? So based upon that preference i can show appropriate message on BiometricPrompt so user wont get confused.

I already explored all api from BiometricPrompt but could find anything related to BiometricPreference.

Any help would be highly appreciated.

How to check user's Bio-Metric Preference through Biometric api?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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大家都知道，从Android9.0开始，安卓引入了BiometricPrompt Api，为越来越多的生物识别传感器(如指纹、人脸ID等)提供标准的认证体验。现在，通过这种新的BiometricPrompt，Api用户可以通过指纹、人脸扫描仪或虹膜扫描(取决于他们的生物特征偏好)进行身份验证。BiometricProm...

问如何通过生物识别api检查用户的生物计量偏好？
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