while working on a security app which needed to get the phone number of who so ever my phone might get into their hands, I had to do this; 1. receive Boot completed and then try getting Line1_Number from telephonyManager which returns a string result. 2. compare the String result with my own phone number and if they don't match or string returns null then, 3. secretly send an SMS containing the string result plus a special sign to my office number. 4. if message sending fails, start a service and keep trying after each hour until sent SMS pending intent returns successful. With this steps I could get the number of the person using my lost phone. it doesn't matter if the person is charged.

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

不建议使用TelephonyManager，因为它要求应用程序在运行时需要READ_PHONE_STATE权限。

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

应该使用谷歌的播放服务进行身份验证，它将能够允许用户选择使用哪个phoneNumber，并处理多个SIM卡，而不是我们试图猜测哪一个是主SIM卡。

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

fun main() {
    val googleApiClient = GoogleApiClient.Builder(context)
        .addApi(Auth.CREDENTIALS_API).build()

    val hintRequest = HintRequest.Builder()
        .setPhoneNumberIdentifierSupported(true)
        .build()

    val hintPickerIntent = Auth.CredentialsApi.getHintPickerIntent(
        googleApiClient, hintRequest
    )

    startIntentSenderForResult(
        hintPickerIntent.intentSender, REQUEST_PHONE_NUMBER, null, 0, 0, 0
    )
}

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    super.onActivityResult(requestCode, resultCode, data)
    when (requestCode) {
        REQUEST_PHONE_NUMBER -> {
            if (requestCode == Activity.RESULT_OK) {
                val credential = data?.getParcelableExtra<Credential>(Credential.EXTRA_KEY)
                val selectedPhoneNumber = credential?.id
            }
        }
    }
}

只是想在以上回答中对以上解释做一点补充。这也会为其他人节省时间。

在我的情况下，这个方法没有返回任何手机号码，返回一个空字符串。这是由于我把我的号码移植到新的sim卡上的情况。所以如果我进入设置>关于电话>状态>我的电话号码，它显示我“未知”。

正如我之前回答的那样

使用以下代码:

TelephonyManager tMgr = (TelephonyManager)mAppContext.getSystemService(Context.TELEPHONY_SERVICE);
String mPhoneNumber = tMgr.getLine1Number();

在AndroidManifest.xml中，赋予以下权限:

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

但请记住，这个代码并不总是有效，因为手机号码取决于SIM卡和网络运营商/手机运营商。

另外，试着在电话->设置->关于->电话身份，如果你能在那里看到号码，从上面的代码获得电话号码的概率更高。如果您不能在设置中查看电话号码，那么您将无法通过此代码获得!

建议解决方案:

获取用户的电话号码作为用户的手动输入。 通过短信将代码发送到用户的手机号码。 请用户输入确认电话号码的代码。 保存在sharedpreference中。

在应用首次发布时一次性执行上述4个步骤。稍后，当需要电话号码时，使用共享首选项中可用的值。

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);
}