SystemServer(一)：恢复出厂设置后wifi、数据流量、gps设置关闭

SystemServer是在虚拟机启动后，开始初始化和运行。其它的系统服务在System Server进程的环境中运行。/base/services/java/com/android/server/SystemServer.java 

我们在initAndLoop（）方法中很快就定位到控制wifi开启或关闭的方法WifiService wifi = null; wifi.checkAndStartWifi();

跟踪到WifiService中的checkAndStartWifi（）；

public void checkAndStartWifi() {
/* Check if wi-fi needs to be enabled */
boolean wifiEnabled = mSettingsStore.isWifiToggleEnabled();
Slog.i(TAG, "WifiService starting up with Wi-Fi " +
(wifiEnabled ? "enabled" : "disabled"));

//FixL1860_Bug00000177,For setWifiEnabled may sometimes have exception.
//So Make sure WifiWatchdogStateMachine is created first.
mWifiWatchdogStateMachine = WifiWatchdogStateMachine.
makeWifiWatchdogStateMachine(mContext);

// If we are already disabled (could be due to airplane mode), avoid changing persist
// state here
//if (wifiEnabled) setWifiEnabled(wifiEnabled);
if (wifiEnabled) setWifiEnabledOnBoot(wifiEnabled);
}

到此我们已经查到了wifi开启或者关闭是由boolean wifiEnabled = mSettingsStore.isWifiToggleEnabled();控制的。

synchronized boolean isWifiToggleEnabled() {
if (!mCheckSavedStateAtBoot) {
mCheckSavedStateAtBoot = true;
if (testAndClearWifiSavedState()) return true;
}

if (mAirplaneModeOn) {
return mPersistWifiState == WIFI_ENABLED_AIRPLANE_OVERRIDE;
} else {
return mPersistWifiState != WIFI_DISABLED;
}
}

我们继续分析代码。发现mCheckSavedStateAtBoot是只我们修改过默认初始值后，手机再次重启将查询我们修改的值。

private boolean testAndClearWifiSavedState() {
final ContentResolver cr = mContext.getContentResolver();
int wifiSavedState = 0;
try {
wifiSavedState = Settings.Global.getInt(cr, Settings.Global.WIFI_SAVED_STATE);
if(wifiSavedState == 1)
Settings.Global.putInt(cr, Settings.Global.WIFI_SAVED_STATE, 0);
} catch (Settings.SettingNotFoundException e) {
;
}
System.out.println("wifiSavedState="+wifiSavedState);
return (wifiSavedState == 1);
}

这段代码会Settings.Global.getInt 数据库里的wifi状态值，当然我们现在是想定位到系统默认值，那么就不做深入分析了，有兴趣的朋友可以自己看看。回到上面isWifiToggleEnabled代码中去，继续分析，这么有一个判断如果是飞行模式则return
mPersistWifiState == WIFI_ENABLED_AIRPLANE_OVERRIDE;不是则return mPersistWifiState != WIFI_DISABLED;。那么这个mPersistWifiState是什么呢？

private int mPersistWifiState = WIFI_DISABLED;它定义的初始值是WIFI_DISABLED，如果异常我们先关闭掉wifi，如果没有异常（这是防止空指针报错赋值），当然我们初始化

WifiSettingsStore对象时，将重新赋值。

WifiSettingsStore(Context context) {
mContext = context;
mAirplaneModeOn = getPersistedAirplaneModeOn();
mPersistWifiState = getPersistedWifiState();
mScanAlwaysAvailable = getPersistedScanAlwaysAvailable();
}

private int getPersistedWifiState() {
final ContentResolver cr = mContext.getContentResolver();
try {
return Settings.Global.getInt(cr, Settings.Global.WIFI_ON);
} catch (Settings.SettingNotFoundException e) {
Settings.Global.putInt(cr, Settings.Global.WIFI_ON, WIFI_DISABLED);
return WIFI_DISABLED;
}
}

这边就是我们获取数据库默认值的方法了。Settings.Global.getInt(cr, Settings.Global.WIFI_ON); WIFI_ON又是什么呢？分析代码后发现其实是数据库的一个字符串。

/**
* Whether the Wi-Fi should be on.  Only the Wi-Fi service should touch this.
*/
public static final String WIFI_ON = "wifi_on"

如何快速定位到这个数据库就要看个人经验了，其实我这边是用了个比较懒的方法，我直接在服务器中搜索的这个字段。如果很快就看到了databaseHelper类了。呵呵，是不是很偷懒。哈哈。

loadBooleanSetting(stmt, Settings.Global.WIFI_ON,
R.bool.def_wifi_on);

这里就可以很清晰的看到wifi_on字段是有R.bool.def_wifi_on控制的。

private void loadBooleanSetting(SQLiteStatement stmt, String key, int resid) {
loadSetting(stmt, key,
mContext.getResources().getBoolean(resid) ? "1" : "0");
}

大致思路就分析到这里了，很多具体的步骤因为太烦躁也没什么难点就不看了，有兴趣的小伙伴可以自己去看看。

同样移动数据，GPS关闭都是由此数据库控制的。

移动数据：

由设置中的DataUsageSummary类setMobileDataEnabled(boolean enabled) 方法获取

mMobileDataEnabled = mConnService.getMobileDataEnabled();boolean值

public boolean getMobileDataEnabled() {
try {
return mService.getMobileDataEnabled();
} catch (RemoteException e) {
return true;
}
}

public boolean getMobileDataEnabled() {
// TODO: This detail should probably be in DataConnectionTracker's
//       which is where we store the value and maybe make this
//       asynchronous.
enforceAccessPermission();
boolean retVal = Settings.Global.getInt(mContext.getContentResolver(),
Settings.Global.MOBILE_DATA, 1) == 1;
if (VDBG) log("getMobileDataEnabled returning " + retVal);
return retVal;
}

</pre></p><p>MOBILE_DATA一样是DataBaseHelper创建的数据库中的字段，不同是他不是由bool值定义的，它SystemProperties一定的，如果没定义则默认返回false。</p><p><pre name="code" class="java">  // Mobile Data default, based on build
loadSetting(stmt, Settings.Global.MOBILE_DATA,
"true".equalsIgnoreCase(

bbea
SystemProperties.get("ro.com.android.mobiledata",
"false")) ? 1 : 0);

GPS：

设置中LocationSettings类。

private boolean getAGPSSwitch() {
int enable = Settings.Global.getInt(mContentResolver,
Settings.Global.ASSISTED_GPS_ENABLED, AGPS_OFF);
return enable == AGPS_ON ? true : false;
}

loadBooleanSetting(stmt, Settings.Global.ASSISTED_GPS_ENABLED,
R.bool.assisted_gps_enabled);