Question

我正在使用NavigationDrawer和一个Activity，我正在替换FrameLayout中的Fragments。浏览NavigationDrawer并替换Activity内部的Fragments非常简单。当我从另一个片段替换片段时，我不确定如何处理。例如：

我展示了一个基本列表片段，当用户点击其中一个项目时，我会显示一个新的片段。现在，从这个新片段中，我可以选择显示另一个片段，这会产生更深层次的片段层次结构。我知道我可以通过 .addToBackStack()，如果是后退按钮，请致电

if (getFragmentManager().getBackStackEntryCount() > 0) {
        getFragmentManager().popBackStack();
    } else {
        super.onBackPressed();
    }

来自Activity的

，但随着Fragment层次结构越深入，它变得越复杂和越脏。是否有一篇好文章或建筑方法来处理像这样的案例？

Answer 1

在您的方案中，您应该使用嵌套片段。您可以将片段嵌入片段中。

要嵌套片段，只需在要添加片段的getChildFragmentManager()上调用Fragment即可。这将返回一个FragmentManager，您可以像往常一样从顶级活动中创建片段事务。例如，这里有一些代码可以在现有的Fragment类中添加片段：

Fragment videoFragment = new VideoPlayerFragment();
FragmentTransaction transaction = getChildFragmentManager().beginTransaction();
transaction.add(R.id.video_fragment, videoFragment).commit();

在嵌套片段中，您可以通过调用getParentFragment().来获取对父片段的引用，然后您的父背斜和子堆栈将被分开。

这是怎么做的。另一个问题是你应该考虑使用intent和新活动而不是10个嵌套片段？这是一篇关于子片段的文章。link Stack similar question

Answer 2

在主要活动中制作片段标签：

 //----------------Fragment TAGS-----------------------\\
    private final String FRAGMENT_BOOK_RIDE = "Frag Book Ride";
    private final String FRAGMENT_RIDE_HISTORY = "Frag Ride History";
    private final String FRAGMENT_PAYMENT = "Frag Payment";
    private final String FRAGMENT_PROFILES_SETTINGS = "Frag Profile & Settings";
    private final String FRAGMENT_HELP = "Frag Help";
    //-----------------------------------------------------\\

导航项目选择：

@SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here. \\
        int id = item.getItemId();

        switch (id) {
            case R.id.nav_book_ride:
                removeAllFragments();
                getSupportActionBar().setTitle(getResources().getString(R.string.app_name));
                getSupportFragmentManager().beginTransaction()
                        .replace(R.id.fragment_container_fl, new BookRideFragment(getApplicationContext())
                                , FRAGMENT_BOOK_RIDE)
                        .commit();
                break;
            case R.id.nav_ride_history:
                removeAllFragments();
                getSupportFragmentManager().beginTransaction()
                        .replace(R.id.fragment_container_fl, new RideHistoryFragment(getApplicationContext())
                                , FRAGMENT_RIDE_HISTORY)
                        .commit();
                break;
            case R.id.nav_payment:
                removeAllFragments();
                getSupportFragmentManager().beginTransaction()
                        .replace(R.id.fragment_container_fl, new PaymentFragment(getApplicationContext())
                                , FRAGMENT_PAYMENT)
                        .commit();
                break;
            case R.id.nav_settings:
                removeAllFragments();
                getSupportFragmentManager().beginTransaction()
                        .replace(R.id.fragment_container_fl, new ProfileSettingFragment(getApplicationContext())
                                , FRAGMENT_PROFILES_SETTINGS)
                        .commit();
                break;
            case R.id.nav_help:
                removeAllFragments();
                getSupportFragmentManager().beginTransaction()
                        .replace(R.id.fragment_container_fl, new HelpFragment(getApplicationContext())
                                , FRAGMENT_HELP)
                        .commit();
                break;
        }

        drawer.closeDrawer(GravityCompat.START);
        return true;
    }

处理backKey按：

@Override
    public void onBackPressed() {
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            backKeyMethods();
        }
    }

    /**
     * Custom back key method for managing fragment back key behavior
     */
    private void backKeyMethods() {
        RideHistoryFragment rideHistoryFragment = (RideHistoryFragment) getSupportFragmentManager().
                findFragmentByTag(FRAGMENT_RIDE_HISTORY);
        PaymentFragment paymentFragment = (PaymentFragment) getSupportFragmentManager().
                findFragmentByTag(FRAGMENT_PAYMENT);
        HelpFragment helpFragment = (HelpFragment) getSupportFragmentManager().
                findFragmentByTag(FRAGMENT_HELP);
        ProfileSettingFragment userProfileFragment = (ProfileSettingFragment) getSupportFragmentManager().
                findFragmentByTag(FRAGMENT_PROFILES_SETTINGS);

        if (rideHistoryFragment != null && rideHistoryFragment.isVisible()) {
            navigationView.setCheckedItem(R.id.nav_book_ride);
            getSupportFragmentManager().beginTransaction()
                    .replace(R.id.fragment_container_fl, new BookRideFragment(getApplicationContext())
                            , FRAGMENT_BOOK_RIDE)
                    .commit();
        } else if (paymentFragment != null && paymentFragment.isVisible()) {
            navigationView.setCheckedItem(R.id.nav_book_ride);
            getSupportFragmentManager().beginTransaction()
                    .replace(R.id.fragment_container_fl, new BookRideFragment(getApplicationContext())
                            , FRAGMENT_BOOK_RIDE)
                    .commit();
        } else if (userProfileFragment != null && userProfileFragment.isVisible()) {
            navigationView.setCheckedItem(R.id.nav_book_ride);
            getSupportFragmentManager().beginTransaction()
                    .replace(R.id.fragment_container_fl, new BookRideFragment(getApplicationContext())
                            , FRAGMENT_BOOK_RIDE)
                    .commit();
        } else if (helpFragment != null && helpFragment.isVisible()) {
            navigationView.setCheckedItem(R.id.nav_book_ride);
            getSupportFragmentManager().beginTransaction()
                    .replace(R.id.fragment_container_fl, new BookRideFragment(getApplicationContext())
                            , FRAGMENT_BOOK_RIDE)
                    .commit();
        } else if (getFragmentManager().getBackStackEntryCount() > 0) {
            getSupportFragmentManager().popBackStack();
        } else {
            super.onBackPressed();
        }
    }

    /**
     * Remove all fragments in Fragment BackStack
     */
    private void removeAllFragments() {
        FragmentManager fm = getSupportFragmentManager();
        for (int i = 0; i < fm.getBackStackEntryCount(); ++i) {
            fm.popBackStack();
        }
    }

每当你想要深入时使用addToBackStack（null），所以当你按下backKey时它将立即弹出片段。希望它有所帮助。

片段被活动中的另一个片段替换，如何导航？

2 个答案: