本文转载自：http://blog.csdn.net/morixinguan/article/details/56675914
frameworks/base/packages/SettingsProvider/src/com/android/providers/settings/DatabaseHelper.java +2519
if (SystemProperties.getBoolean("ro.lockscreen.disable.default", false) == true)
改为
if (SystemProperties.getBoolean("ro.lockscreen.disable.default", true) == true)