Android TelephonyManager双卡获取数据开启状态异常的可能原因

背景

应用内不指定subId获取数据状态可能会错误，因为可能拿到voice的能力，而非data。

代码逻辑

1、通过TelephonyManager的isDataEnabled()没有指定subId时，调用内部方法isDataEnabledForReason，传入getId()参数以指定subid，然后会执行到SubscriptionManager的getDefaultDataSubscriptionId()以获取默认值，

/**
 * Returns whether mobile data is enabled or not per user setting. There are other factors
 * that could disable mobile data, but they are not considered here.
 *
 * If this object has been created with {@link #createForSubscriptionId}, applies to the given
 * subId. Otherwise, applies to {@link SubscriptionManager#getDefaultDataSubscriptionId()}
 *
 * <p>Requires one of the following permissions:
 * {@link android.Manifest.permission#ACCESS_NETWORK_STATE},
 * {@link android.Manifest.permission#MODIFY_PHONE_STATE}, or
 * {@link android.Manifest.permission#READ_BASIC_PHONE_STATE
 * READ_BASIC_PHONE_STATE} or that the calling app has carrier
 * privileges (see {@link #hasCarrierPrivileges}).
 *
 * <p>Note that this does not take into account any data restrictions that may be present on the
 * calling app. Such restrictions may be inspected with
 * {@link ConnectivityManager#getRestrictBackgroundStatus}.
 *
 * @return true if mobile data is enabled.
 */
@RequiresPermission(anyOf = {android.Manifest.permission.ACCESS_NETWORK_STATE,
        android.Manifest.permission.MODIFY_PHONE_STATE,
        android.Manifest.permission.READ_PHONE_STATE,
        android.Manifest.permission.READ_BASIC_PHONE_STATE})
@RequiresFeature(PackageManager.FEATURE_TELEPHONY_DATA)
public boolean isDataEnabled() {
    try {
        return isDataEnabledForReason(DATA_ENABLED_REASON_USER);
    } catch (IllegalStateException ise) {
        // TODO(b/176163590): Remove this catch once TelephonyManager is booting safely.
        Log.e(TAG, "Error calling #isDataEnabled, returning default (false).", ise);
        return false;
    }
}

2、根据SubscriptionManager逻辑，会查询获取DefaultSubId的值，最终用的是SubscriptionController数据

/**
 * Returns the system's default data subscription id.
 *
 * On a voice only device or on error, will return INVALID_SUBSCRIPTION_ID.
 *
 * @return the default data subscription Id.
 */
public static int getDefaultDataSubscriptionId() {
    return sDefaultDataSubIdCache.query(null);
}

3、SubscriptionController的逻辑，未指定subid时拿到的会是voice的能力

使用方法和说明

在Android中，TelephonyManager类的isDataEnabled()方法用于检查移动数据连接是否启用。而subId（Subscription ID）是用于标识不同SIM卡的唯一ID。

Note：isDataEnable()可不传入参数，即默认的subId（使用getDefaultDataSubscriptionId()方法获取），也可以指定subId（如下代码示例）。

在多卡手机中，可以通过TelephonyManager的getSubId()方法获取当前活动的SIM卡的SubId，
然后可使用TelephonyManager.isDataEnabled()方法检查指定的subId对应的SIM卡的移动数据链接是否启用

代码示例：

TelephonyManager  mTelephonyManager = (TelephonyManager) getSystemService(context.TELEPHONY_SERVICE);

int subId = 1; //要检查的SIM的subId

if(mTelephonyManager.isDataEnabled(subId)) {
    //移动数据已启用
} else {
    //移动数据未启用
}