安卓7.1/7.0/6.x WiFi和信号图标出现感叹号的解决方法

1、简单的单机机器解决：

adb shell settings delete global captive_portal_server  
adb shell settings put global captive_portal_detection_enabled 0

2、系统源码着手：

路径：frameworks/base/packages/SettingsProvider

/res/values/defaults.xml:

<integer name="def_captive_portal_detection_enabled">0</integer>

/src/com/android/providers/settings/DatabaseHelper.java:

@method:private void loadGlobalSettings(SQLiteStatement stmt) {
  loadIntegerSetting(stmt, Global.CAPTIVE_PORTAL_DETECTION_ENABLED,
                    R.integer.def_captive_portal_detection_enabled);