enable usb debugging by code

http://www.linuxidc.com/Linux/2011-10/46146.htm

packages/apps/Settings/src/com/android/settings/DevelopmentSettings.java

Settings.Secure.putInt(getContentResolver(), Settings.Secure.ADB_ENABLED,  0 );

frameworks/base/services/java/com/android/server/NotificationManagerService.java

void  observe() {
    ContentResolver resolver = mContext.getContentResolver();
    resolver.registerContentObserver(Settings.Secure.getUriFor(
            Settings.Secure.ADB_ENABLED), false ,  this );
    update();
}

@Override   public   void  onChange( boolean  selfChange) {
    update();
}

public   void  update() {
    ContentResolver resolver = mContext.getContentResolver();
    mAdbEnabled = Settings.Secure.getInt(resolver,
                Settings.Secure.ADB_ENABLED, 0 ) !=  0 ;
    updateAdbNotification();
}

boolean enableAdb = (Settings.Secure.getInt(getContentResolver(), Settings.Secure.ADB_ENABLED, 0) > 0);
    if (!enableAdb) {
    Settings.Secure.putInt(getContentResolver(), Settings.Secure.ADB_ENABLED, 1);
    }

/system/app

AndroidManifest.xml

<uses-permission android:name="android.permission.WRITE_SETTINGS"></uses-permission>
<uses-permission android:name="android.permission.WRITE_SECURE_SETTINGS" />