is a way to disable auto connect to wifi that don't need password? it is really annoying that my mobile phone will auto connect to wifi that don't need password such as those ones in shopping center, most of time they need you to fill up a form to register first before access granted, and I have to turn off wifi for this reason. Then when I go home, sometimes I forget to turn wifi back on and waste my moble plan data usage, is a way to fix this issue? I can't believe that Android doesn't have a mechanism to only connect to wifi you have previously provide password?
You can use ADB to disable it:
adb shell settings put global wifi_scan_always_enabled 0 
adb shell settings put global network_avoid_bad_wifi 1