禁用三星"Auto Network Switch"以进行 WiFi 连接

Question

在我们的应用程序中，我们处理启动与设备的WiFi连接，该设备广播自己的无线接入点（没有互联网连接）以进行直接通信。

它在我们所有的测试设备上都能很好地工作；然而，我们收到用户的报告，在某些三星设备（Galaxy S4、Galaxy Note 3）上，三星添加了一个名为"自动网络切换"的Wi-Fi设置，用于查找"不稳定"的网络，并将自动断开连接并恢复到移动数据。不幸的是，由于我们的设备没有互联网连接，三星报告称其网络不稳定，并立即断开连接。

我没有这两种设备可供测试，所以我很好奇是否有其他人知道这个问题，或者知道通过编程禁用或解决这个设置的方法？

我们用于连接的代码是：

/**
 * Attempt to connect to an open wifi network with the given SSID
 * @param ssid the SSID of the unsecured wireless network to connect to
 */
public static void connectToOpenNetwork (String ssid) {
    WifiManager mgr = getManager();
    WifiConfiguration configuration = getOpenWifiConfiguration(ssid);
    mgr.addNetwork(configuration);
    mgr.saveConfiguration();
    int res = findOpenNetworkId(ssid);
    if (res != INVALID_NETWORK_ID) {
        mgr.enableNetwork(res, true);
        mgr.reconnect();
    } else {
        Log.e(TAG, "Received request to connect to network " + ssid + " but the network was not found in the configurations.");
    }
}
/**
 * Get a WifiConfiguration object configured for an unsecured wireless network with the
 * given SSID.
 * @param ssid the SSID of the network to configure
 * @return a WifiConfiguration object that can be passed to
 * {@link WifiManager#addNetwork(android.net.wifi.WifiConfiguration)}
 */
private static WifiConfiguration getOpenWifiConfiguration (String ssid) {
    WifiConfiguration config = new WifiConfiguration();
    config.SSID = """ + ssid + """;
    config.allowedKeyManagement.set(WifiConfiguration.KeyMgmt.NONE);
    return config;
}

Answer 1

EDIT：因此，对于那些感兴趣的人来说，这似乎是三星Touchwiz基于4.3版本中添加的一个功能。在内部，该设置命名为"wifi_watchdog_connectivity_check"。我仍然使用下面的代码来查看我是否能够检查确定是否启用了设置，但否则我必须假设它是打开的。

因此，我发现，在你尝试连接后，操作系统从网络切换开，Wi-Fi配置处于"禁用"状态。因此，在问题发生后，您可以通过检查WifiManager中的配置状态来确定是否发生了问题。

WifiManager m = (WifiManger) getSystemService(Context.WIFI_SERVICE);
List<WifiConfiguration> networks = m.getConfiguredNetworks();
String mySsid = "My Network";
mySsid = """ + mySsid + """;
boolean isDisabled = false;
for (WifiConfiguration config : networks) {
    if (mySsid.equals(config.SSID)) {
        if (config.status = WifiConfiguration.Status.DISABLED) {
            isDisabled = true;
            break;
        }
    }
}
//If isDisabled is true, the network was disabled by the OS

然后，您可以尝试从系统设置应用程序解析设置的名称：

/** Gets the resources of another installed application */
private static Resources getExternalResources(Context ctx, String namespace) {
    PackageManager pm = ctx.getPackageManager();
    try {
        return (pm == null) ? null : pm.getResourcesForApplication(namespace);
    } catch (PackageManager.NameNotFoundException ex) {
        return null;
    }
}
/** Gets a resource ID from another installed application */
private static int getExternalIdentifier(Context ctx, String namespace, 
        String key, String type) {
    Resources res = getExternalResources(ctx, namespace);
    return (res == null) ? 0 : res.getIdentifier(key, type, namespace);
}
/** Gets a String resource from another installed application */
public static String getExternalString(Context ctx, String namespace, 
        String key, String defVal) {
    int resId = getExternalIdentifier(ctx, namespace, key, "string");
    if (resId != 0) {
        Resources res = getExternalResources(ctx, namespace);
        return res.getString(resId);
    } else {
        return defVal;
    }
}

然后使用它来获得字符串：

String autoNetworkSwitch = getExternalString(this, "com.android.settings",
        "wifi_watchdog_connectivity_check", "Unknown");

这将返回当前用户语言的本地化字符串（如果该字符串存在）。

---

对于任何对此结果感兴趣的人来说，事实证明，这个选项实际上是安卓系统的一个常见设置，但在这些三星设备上似乎更具攻击性。该设置是android.provider.Settings.java:中的隐藏设置

/**
 * Setting to turn off poor network avoidance on Wi-Fi. Feature is enabled by default and
 * the setting needs to be set to 0 to disable it.
 * @hide
 */
public static final String WIFI_WATCHDOG_POOR_NETWORK_TEST_ENABLED =
       "wifi_watchdog_poor_network_test_enabled";

其中对于API == 15 || API == 16在Settings$Secure中，或者对于API >= 17在Settings$Global中。这不是一个可以由第三方应用程序启用或禁用的设置；然而，它可以被检测到并被警告。我的解决方案是：

import static android.os.Build.VERSION.SDK_INT;
import static android.os.Build.VERSION_CODES.ICE_CREAM_SANDWICH_MR1;
import static android.os.Build.VERSION_CODES.JELLY_BEAN_MR1;
/**
 * Checks whether the "Avoid poor networks" setting (named "Auto network switch" on 
 * some Samsung devices) is enabled, which can in some instances interfere with Wi-Fi.
 *
 * @return true if the "Avoid poor networks" or "Auto network switch" setting is enabled
 */
public static boolean isPoorNetworkAvoidanceEnabled (Context ctx) {
    final int SETTING_UNKNOWN = -1;
    final int SETTING_ENABLED = 1;
    final String AVOID_POOR = "wifi_watchdog_poor_network_test_enabled";
    final String WATCHDOG_CLASS = "android.net.wifi.WifiWatchdogStateMachine";
    final String DEFAULT_ENABLED = "DEFAULT_POOR_NETWORK_AVOIDANCE_ENABLED";
    final ContentResolver cr = ctx.getContentResolver();
    int result;
    if (SDK_INT >= JELLY_BEAN_MR1) {
        //Setting was moved from Secure to Global as of JB MR1
        result = Settings.Global.getInt(cr, AVOID_POOR, SETTING_UNKNOWN);
    } else if (SDK_INT >= ICE_CREAM_SANDWICH_MR1) {
        result = Settings.Secure.getInt(cr, AVOID_POOR, SETTING_UNKNOWN);
    } else {
        //Poor network avoidance not introduced until ICS MR1
        //See android.provider.Settings.java
        return false;
    }
    //Exit here if the setting value is known
    if (result != SETTING_UNKNOWN) {
        return (result == SETTING_ENABLED);
    }
    //Setting does not exist in database, so it has never been changed.
    //It will be initialized to the default value.
    if (SDK_INT >= JELLY_BEAN_MR1) {
        //As of JB MR1, a constant was added to WifiWatchdogStateMachine to determine 
        //the default behavior of the Avoid Poor Networks setting.
        try {
            //In the case of any failures here, take the safe route and assume the 
            //setting is disabled to avoid disrupting the user with false information
            Class wifiWatchdog = Class.forName(WATCHDOG_CLASS);
            Field defValue = wifiWatchdog.getField(DEFAULT_ENABLED);
            if (!defValue.isAccessible()) defValue.setAccessible(true);
            return defValue.getBoolean(null);
        } catch (IllegalAccessException ex) {
            return false;
        } catch (NoSuchFieldException ex) {
            return false;
        } catch (ClassNotFoundException ex) {
            return false;
        } catch (IllegalArgumentException ex) {
            return false;
        }
    } else {
        //Prior to JB MR1, the default for the Avoid Poor Networks setting was
        //to enable it unless explicitly disabled
        return true;
    }
}

为了更好地衡量，您可以通过Intent:将用户引导到高级Wi-Fi设置

/**
 *  Ensure that an Activity is available to receive the given Intent
 */
public static boolean activityExists (Context ctx, Intent intent) {
    final PackageManager mgr = ctx.getPackageManager();
    final ResolveInfo info = mgr.resolveActivity(i, PackageManager.MATCH_DEFAULT_ONLY);
    return (info != null);
}
public static void showAdvancedWifiIfAvailable (Context ctx) {
    final Intent i = new Intent(Settings.ACTION_WIFI_IP_SETTINGS);
    if (activityExists(ctx, i)) {
        ctx.startActivity(i);
    }
}

有趣的琐事：这个Intent会显示与"设置">"Wi-Fi">"高级"相同的Activity，但会显示不同的标题（IP设置与高级Wi-Fi）。