在Android中使用片段时处理后退

Question

我在我的应用程序中使用导航抽屉使用Android滑动菜单,而在应用程序中使用碎片而不是活动.当我打开抽屉时,单击片段出现的项目.我使用以下代码从一个片段移动到另一个片段:

Fragment fragment = null;
fragment = new GalleryFragment(selectetdMainMenu.getCategoryID());
                    FragmentTransaction ft = getFragmentManager().beginTransaction();
                    ft.addToBackStack("menuFrag");
                    ft.add(R.id.frame_container, fragment, "menuFrag");
                    ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
                    ft.commit();

通过这种方式,我可以从一个片段转到另一个片段但是我无法按下后退按钮上的前一个片段.我设法提出这个代码来处理MainActivity中的反压,其中Drawer初始化:

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    super.onKeyDown(keyCode, event);
    if (keyCode == KeyEvent.KEYCODE_BACK) {
        Fragment fragment_byTag = fragmentManager.findFragmentByTag("menuFrag");
        Fragment menuFragment_by_tag = fragmentManager.findFragmentByTag("galleryFrag");
        Fragment commentsFrag_by_tag = fragmentManager.findFragmentByTag("commentsFrag");
        Fragment dealDetail = fragmentManager.findFragmentByTag("promoFrag");
            if(commentsFrag_by_tag != null){
                if (commentsFrag_by_tag.isVisible()) {
                    Log.e("comments back  ", " clicked");
                    //menuDetailsFrag.onBackPressed();
                    FragmentManager fragmentManager = getSupportFragmentManager();
                    fragmentManager.beginTransaction().remove(commentsFrag_by_tag).commit();
                    fragmentManager.beginTransaction().show(menuFragment_by_tag).commit();
                }
            }else if(menuFragment_by_tag.isVisible()){
                Log.e("menu back  ", " clicked");
                menuDetailsFrag.onBackPressed();
                FragmentManager fragmentManager = getSupportFragmentManager();
                fragmentManager.beginTransaction().remove(menuFragment_by_tag).commit();
                fragmentManager.beginTransaction().show(fragment_byTag).commit();
            }
        }



    return false;
}

这有时会起作用,但大部分时间都会失败.如果可以显示更好的导航方式,我将不胜感激.

Answer 1

我通常设置onKeyListener为Viewin onResume.从我所学到的,你必须要小心设置setFocusableInTouchMode()和requestFocus上View.

这是我用于此目的的示例:

@Override
public void onResume() {

    super.onResume();

    getView().setFocusableInTouchMode(true);
    getView().requestFocus();
    getView().setOnKeyListener(new View.OnKeyListener() {
        @Override
        public boolean onKey(View v, int keyCode, KeyEvent event) {

            if (event.getAction() == KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_BACK){

                // handle back button

                return true;

            }

            return false;
        }
    });
}

Answer 2

试试这些方法.对我来说,最有用的解决方案如下:

在MainActivity中:

getSupportFragmentManager().beginTransaction().replace(R.id.gif_contents, gifPageTwoFragment, "gifPageTwoFragment").addToBackStack("gifPageTwoFragment").commit();

在GifPageTwoFragment中:

@Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        getView().setFocusableInTouchMode(true);
        getView().requestFocus();
        getView().setOnKeyListener(new View.OnKeyListener() {
            @Override
            public boolean onKey(View v, int keyCode, KeyEvent event) {
                if (event.getAction() == KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_BACK) {
                    Log.e("gif--","fragment back key is clicked");
                    getActivity().getSupportFragmentManager().popBackStack("gifPageTwoFragment", FragmentManager.POP_BACK_STACK_INCLUSIVE);
                    return true;
                }
                return false;
            }
        });
    }