android 开启6g热点，设定的band值为5，最终写入文件的band值却为7.

packages/apps/Settings/src/com/android/settings/wifi/tether/WifiTetherApBandPreferenceController.java

这个类在开启热点的界面负责设置热点的频段。

在解决一个热点的问题时，发现设置6G热点的时候明明设置的值为5 ，在保存到xml文件的时候就变为了7.   导致获取频段值时没有对应上。

在开启热点的界面里，选择频段时。会先将热点的配置保存在一个xml文件里面。开启热点时，会直接拿取配置文件的值进行开启热点。

这个配置文件在手机的  data/misc/apexdata/com.android.wifi/     下。里面有两个配置文件，一个是wifi的，一个是热点的。

设置的方法为     wifiManager.setSoftApConfiguration()

这个的实现是在packages/modules/Wifi/service/java/com/android/server/wifi/WifiServiceImpl.java

@Override
    public boolean setSoftApConfiguration(
            @NonNull SoftApConfiguration softApConfig, @NonNull String packageName) {
        int uid = Binder.getCallingUid();
        mWifiPermissionsUtil.checkPackage(uid, packageName);
        boolean privileged = mWifiPermissionsUtil.checkNetworkSettingsPermission(uid);
        if (!mWifiPermissionsUtil.checkConfigOverridePermission(uid)
                && !privileged) {
            // random apps should not be allowed to read the user specified config
            throw new SecurityException("App not allowed to read or update stored WiFi Ap config "
                    + "(uid = " + uid + ")");
        }
        mLog.info("setSoftApConfiguration uid=%").c(uid).flush();
        if (softApConfig == null) return false;
        if (WifiApConfigStore.validateApWifiConfiguration(softApConfig, privileged, mContext)) {
            mWifiApConfigStore.setApConfiguration(softApConfig);
            // Send the message for AP config update after the save is done.
            mActiveModeWarden.updateSoftApConfiguration(softApConfig);
            return true;
        } else {
            Log.e(TAG, "Invalid SoftAp Configuration");
            return false;
        }
    }

看这个  mWifiApConfigStore.setApConfiguration(softApConfig);

packages/modules/Wifi/service/java/com/android/server/wifi/WifiApConfigStore.java

public synchronized void setApConfiguration(SoftApConfiguration config) {
        SoftApConfiguration newConfig = config == null ? getDefaultApConfiguration()
                : new SoftApConfiguration.Builder(sanitizePersistentApConfig(config))
                        .setUserConfiguration(true).build();
        persistConfigAndTriggerBackupManagerProxy(
                updatePersistentRandomizedMacAddress(newConfig));
    }

关注   sanitizePersistentApConfig(config)

private SoftApConfiguration sanitizePersistentApConfig(SoftApConfiguration config) {
        SoftApConfiguration.Builder convertedConfigBuilder =
                new SoftApConfiguration.Builder(config);
        int[] bands = config.getBands();
        SparseIntArray newChannels = new SparseIntArray();
        // The bands length should always 1 in R. Adding SdkLevel.isAtLeastS for lint check only.
        for (int i = 0; i < bands.length; i++) {
            int channel = SdkLevel.isAtLeastS()
                    ? config.getChannels().valueAt(i) : config.getChannel();
            int newBand = bands[i];
            if (channel == 0 && mIsAutoAppendLowerBandEnabled
                    && ApConfigUtil.isBandSupported(newBand, mContext)) {
                // some countries are unable to support 5GHz only operation, always allow for 2GHz
                // when config doesn't force channel
                if ((newBand & SoftApConfiguration.BAND_2GHZ) == 0) {
                    newBand = ApConfigUtil.append24GToBandIf24GSupported(newBand, mContext);
                }
                // If the 6G configuration doesn't includes 5G band (2.4G have appended because
                // countries reason), it will cause that driver can't switch channel from 6G to
                // 5G/2.4G when coexistence happened (For instance: wifi connected to 2.4G or 5G
                // channel). Always append 5G into band configuration when configured band includes
                // 6G.
                if ((newBand & SoftApConfiguration.BAND_6GHZ) != 0
                        && (newBand & SoftApConfiguration.BAND_5GHZ) == 0) {
                    newBand = ApConfigUtil.append5GToBandIf5GSupported(newBand, mContext);
                }
            }
            newChannels.put(newBand, channel);
        }
        if (SdkLevel.isAtLeastS()) {
            convertedConfigBuilder.setChannels(newChannels);
        } else if (bands.length > 0 && newChannels.valueAt(0) == 0) {
            convertedConfigBuilder.setBand(newChannels.keyAt(0));
        }
        return convertedConfigBuilder.build();

看这个

if ((newBand & SoftApConfiguration.BAND_6GHZ) != 0
&& (newBand & SoftApConfiguration.BAND_5GHZ) == 0) {
newBand = ApConfigUtil.append5GToBandIf5GSupported(newBand, mContext);
}

packages/modules/Wifi/service/java/com/android/server/wifi/util/ApConfigUtil.java

public static @BandType int append5GToBandIf5GSupported(@BandType int targetBand,
            Context context) {
        if (isBandSupported(SoftApConfiguration.BAND_5GHZ, context)) {
            return targetBand | SoftApConfiguration.BAND_5GHZ;
        }
        return targetBand;
    }

这个方法里面会将传入的5  加上  2  就变为了  7

至于原因上面也做出了解释。

如果6G配置不包括5G频段（由于国家原因，附加了2.4G），则会导致共存时驱动器无法将信道从6G切换到5G/2.4G（例如：连接到2.4G或5G信道的wifi）。当配置的频段包括6G时，始终将5G附加到频段配置中。

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