private String getMyPhoneNumber(){
    TelephonyManager mTelephonyMgr;
    mTelephonyMgr = (TelephonyManager)
        getSystemService(Context.TELEPHONY_SERVICE); 
    return mTelephonyMgr.getLine1Number();
}

private String getMy10DigitPhoneNumber(){
    String s = getMyPhoneNumber();
    return s != null && s.length() > 2 ? s.substring(2) : null;
}

代码摘自http://www.androidsnippets.com/get-my-phone-number

以下是我找到的解决方案的组合(这里是示例项目，如果你也想检查自动填充):

清单

    <uses-permission android:name="android.permission.READ_PHONE_STATE" />

build.gradle

    implementation "com.google.android.gms:play-services-auth:17.0.0"

MainActivity.kt

class MainActivity : AppCompatActivity() {
    private lateinit var googleApiClient: GoogleApiClient

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        tryGetCurrentUserPhoneNumber(this)
        googleApiClient = GoogleApiClient.Builder(this).addApi(Auth.CREDENTIALS_API).build()
        if (phoneNumber.isEmpty()) {
            val hintRequest = HintRequest.Builder().setPhoneNumberIdentifierSupported(true).build()
            val intent = Auth.CredentialsApi.getHintPickerIntent(googleApiClient, hintRequest)
            try {
                startIntentSenderForResult(intent.intentSender, REQUEST_PHONE_NUMBER, null, 0, 0, 0);
            } catch (e: IntentSender.SendIntentException) {
                Toast.makeText(this, "failed to show phone picker", Toast.LENGTH_SHORT).show()
            }
        } else
            onGotPhoneNumberToSendTo()

    }

    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        if (requestCode == REQUEST_PHONE_NUMBER) {
            if (resultCode == Activity.RESULT_OK) {
                val cred: Credential? = data?.getParcelableExtra(Credential.EXTRA_KEY)
                phoneNumber = cred?.id ?: ""
                if (phoneNumber.isEmpty())
                    Toast.makeText(this, "failed to get phone number", Toast.LENGTH_SHORT).show()
                else
                    onGotPhoneNumberToSendTo()
            }
        }
    }

    private fun onGotPhoneNumberToSendTo() {
        Toast.makeText(this, "got number:$phoneNumber", Toast.LENGTH_SHORT).show()
    }


    companion object {
        private const val REQUEST_PHONE_NUMBER = 1
        private var phoneNumber = ""

        @SuppressLint("MissingPermission", "HardwareIds")
        private fun tryGetCurrentUserPhoneNumber(context: Context): String {
            if (phoneNumber.isNotEmpty())
                return phoneNumber
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                val subscriptionManager = context.getSystemService(Context.TELEPHONY_SUBSCRIPTION_SERVICE) as SubscriptionManager
                try {
                    subscriptionManager.activeSubscriptionInfoList?.forEach {
                        val number: String? = it.number
                        if (!number.isNullOrBlank()) {
                            phoneNumber = number
                            return number
                        }
                    }
                } catch (ignored: Exception) {
                }
            }
            try {
                val telephonyManager = context.getSystemService(Context.TELEPHONY_SERVICE) as TelephonyManager
                val number = telephonyManager.line1Number ?: ""
                if (!number.isBlank()) {
                    phoneNumber = number
                    return number
                }
            } catch (e: Exception) {
            }
            return ""
        }
    }
}

首先在Intent中初始化你的符号

private val signInIntent = registerForActivityResult(ActivityResultContracts.StartIntentSenderForResult()) { result ->
        try {
            val phoneNumber = Identity.getSignInClient(requireContext()).getPhoneNumberFromIntent(result.data)
            // Note phone number will be in country code + phone number format           
        } catch (e: Exception) {
        }
    }

要打开谷歌播放意图，并显示与谷歌帐户相关联的电话号码，请使用此

val phoneNumberHintIntentRequest = GetPhoneNumberHintIntentRequest.builder()
            .build()
        Identity.getSignInClient(requireContext())
            .getPhoneNumberHintIntent(phoneNumberHintIntentRequest)
            .addOnSuccessListener { pendingIntent ->
                signInIntent.launch(IntentSenderRequest.Builder(pendingIntent).build())
            }.addOnFailureListener {
                it.printStackTrace()
            }

注意:

如果用户禁用电话号码共享，此操作将失败。如果是这样，用户必须从设置->谷歌->自动填充->电话号码共享 如果您正在使用播放服务不可用的模拟设备，这将不起作用

这是一个更简单的答案:

public String getMyPhoneNumber()
{
    return ((TelephonyManager) getSystemService(TELEPHONY_SERVICE))
            .getLine1Number();
}

这个问题没有保证的解决方案，因为电话号码不是物理地存储在所有sim卡上，也不是从网络广播到电话上。在一些需要物理地址验证的国家尤其如此，只有在验证之后才会分配号码。电话号码分配是在网络上进行的，并且可以在不改变SIM卡或设备的情况下进行更改(例如，这就是支持移植的方式)。

我知道这很痛苦，但最有可能的最好的解决方案是让用户输入一次他/她的电话号码并存储它。

有一个新的Android api，允许用户选择他们的电话号码，而不需要权限。来看看: https://android-developers.googleblog.com/2017/10/effective-phone-number-verification.html

// Construct a request for phone numbers and show the picker
private void requestHint() {
    HintRequest hintRequest = new HintRequest.Builder()
       .setPhoneNumberIdentifierSupported(true)
       .build();

    PendingIntent intent = Auth.CredentialsApi.getHintPickerIntent(
        apiClient, hintRequest);
    startIntentSenderForResult(intent.getIntentSender(),
        RESOLVE_HINT, null, 0, 0, 0);
}