android-屏蔽back键，保证在点击back键时dialog对话框不会消失

mSaveingProgressDialog.setOnKeyListener(mDialogOnKeylistener);    
DialogInterface.OnKeyListener mDialogOnKeylistener = new DialogInterface.OnKeyListener(){
    public boolean (DialogInterface dialog, int keyCode, KeyEvent event) {
        if (mSaveing) {
            if (KeyEvent.KEYCODE_BACK == keyCode) {
                return true;
            }
        }
        return false;
    }
} ;