Android Lollipop 工具栏在打开/关闭抽屉和后退按钮之间切换

Question

我有标准的抽屉导航，但现在我正在尝试使用工具栏修改它。

之前我的代码是这样的:MainActivity.java

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Log.v("MAIN", "CREATE");
    initViews();
    setListeners();

    getFragmentManager().addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
        @Override
        public void onBackStackChanged() {
            shouldDisplayHomeUp();
        }
    });

    mNavigationDrawerFragment = (NavigationDrawerFragment)
            getFragmentManager().findFragmentById(R.id.navigation_drawer);
    mTitle = getTitle();

    // Set up the drawer.
    mNavigationDrawerFragment.setUp(
            R.id.navigation_drawer,
            (DrawerLayout) findViewById(R.id.drawer_layout));
}

NavigationDrawerFragment.java

public void setUp(int fragmentId, DrawerLayout drawerLayout) {
    mFragmentContainerView = getActivity().findViewById(fragmentId);
    mDrawerLayout = drawerLayout;

    mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);

    ((MainActivity) getActivity()).getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    ((MainActivity) getActivity()).getSupportActionBar().setHomeButtonEnabled(true);

    mDrawerToggle = new ActionBarDrawerToggle(getActivity(), mDrawerLayout,
            ((MainActivity) getActivity()).getToolbar(),
            R.string.navigation_drawer_open,
            R.string.navigation_drawer_close) {
        @Override
        public void onDrawerClosed(View drawerView) {
            super.onDrawerClosed(drawerView);
            if (!isAdded()) {
                return;
            }

            getActivity().invalidateOptionsMenu(); // calls onPrepareOptionsMenu()
        }

        @Override
        public void onDrawerOpened(View drawerView) {
            super.onDrawerOpened(drawerView);
            if (!isAdded()) {
                return;
            }

            if (!mUserLearnedDrawer) {
                // The user manually opened the drawer; store this flag to prevent auto-showing
                // the navigation drawer automatically in the future.
                mUserLearnedDrawer = true;
                SharedPreferences sp = PreferenceManager
                        .getDefaultSharedPreferences(getActivity());
                sp.edit().putBoolean(PREF_USER_LEARNED_DRAWER, true).apply();
            }
            if (mDrawerListView != null) {

            }
            getActivity().invalidateOptionsMenu(); // calls onPrepareOptionsMenu()
        }

        @Override
        public void onDrawerSlide(View drawerView, float slideOffset) {
            super.onDrawerSlide(drawerView, slideOffset);
        }
    };

    // If the user hasn't 'learned' about the drawer, open it to introduce them to the drawer,
    // per the navigation drawer design guidelines.
    if (!mUserLearnedDrawer && !mFromSavedInstanceState) {
        mDrawerLayout.openDrawer(mFragmentContainerView);
    }

    // Defer code dependent on restoration of previous instance state.

    mDrawerToggle.setDrawerIndicatorEnabled(true);

    mDrawerLayout.post(new Runnable() {
        @Override
        public void run() {
            mDrawerToggle.syncState();
        }
    });

    mDrawerLayout.setDrawerListener(mDrawerToggle);
}

现在我修改了我的代码:MainActivity.java

 @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mToolbar = (Toolbar) findViewById(R.id.toolbar);

    if (mToolbar != null) {
        setSupportActionBar(mToolbar);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    }

    initViews();
    setListeners();

    mNavigationDrawerFragment = (NavigationDrawerFragment)
            getFragmentManager().findFragmentById(R.id.navigation_drawer);
    mTitle = getTitle();

    // Set up the drawer.
    mNavigationDrawerFragment.setUp(
            R.id.navigation_drawer,
            (DrawerLayout) findViewById(R.id.drawer_layout));


    shouldDisplayHomeUp();

    getFragmentManager().addOnBackStackChangedListener(new FragmentManager.OnBackStackChangedListener() {
        @Override
        public void onBackStackChanged() {
            mBackCount++;
            shouldDisplayHomeUp();
        }
    });
}

NavigationDrawerFragment.java

public void setUp(int fragmentId, DrawerLayout drawerLayout) {
    mFragmentContainerView = getActivity().findViewById(fragmentId);
    mDrawerLayout = drawerLayout;

    mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);

    mDrawerToggle = new ActionBarDrawerToggle(getActivity(), mDrawerLayout,
            ((MainActivity) getActivity()).getToolbar(),
            R.string.navigation_drawer_open,
            R.string.navigation_drawer_close) {
        @Override
        public void onDrawerClosed(View drawerView) {
            super.onDrawerClosed(drawerView);
            if (!isAdded()) {
                return;
            }

            getActivity().invalidateOptionsMenu(); // calls onPrepareOptionsMenu()
        }

        @Override
        public void onDrawerOpened(View drawerView) {
            super.onDrawerOpened(drawerView);
            if (!isAdded()) {
                return;
            }

            if (!mUserLearnedDrawer) {
                // The user manually opened the drawer; store this flag to prevent auto-showing
                // the navigation drawer automatically in the future.
                mUserLearnedDrawer = true;
                SharedPreferences sp = PreferenceManager
                        .getDefaultSharedPreferences(getActivity());
                sp.edit().putBoolean(PREF_USER_LEARNED_DRAWER, true).apply();
            }
            if (mDrawerListView != null) {

            }
            getActivity().invalidateOptionsMenu(); // calls onPrepareOptionsMenu()
        }

        @Override
        public void onDrawerSlide(View drawerView, float slideOffset) {
            super.onDrawerSlide(drawerView, slideOffset);
        }
    };

    // If the user hasn't 'learned' about the drawer, open it to introduce them to the drawer,
    // per the navigation drawer design guidelines.
    if (!mUserLearnedDrawer && !mFromSavedInstanceState) {
        mDrawerLayout.openDrawer(mFragmentContainerView);
    }

    // Defer code dependent on restoration of previous instance state.

    mDrawerToggle.setDrawerIndicatorEnabled(true);

    mDrawerLayout.post(new Runnable() {
        @Override
        public void run() {
            mDrawerToggle.syncState();
        }
    });

    mDrawerLayout.setDrawerListener(mDrawerToggle);
}

和shouldDisplayHomeUp函数:

public void shouldDisplayHomeUp (){
    boolean canBack = getFragmentManager().getBackStackEntryCount() > 0;
    mNavigationDrawerFragment.getDrawerToggle().setDrawerIndicatorEnabled(!canBack);
}

但是后退箭头没有显示

我试过打电话

getSupportActionBar().setDisplayHomeAsUpEnabled(canBack);
getSupportActionBar().setHomeButtonEnabled(canBack);

所以出现了后退箭头但是点击它没有效果

Answer 1

来自文档:

To allow Up navigation with the app icon in the action bar, call setDisplayHomeAsUpEnabled():

@Override public void onCreate(Bundle savedInstanceState) {
     ...
     getActionBar().setDisplayHomeAsUpEnabled(true); }

This adds a left-facing caret alongside the app icon and enables it as an action button such that when the user presses it, your activity receives a call to onOptionsItemSelected(). The ID for the action is android.R.id.home.

这意味着您将必须在 onOptionsItemSelected 上执行您的返回例程并检查 R.id.home。为避免在单击汉堡包菜单时调用例程，请在 onOptionsItemSelected 上检查 canback。

http://developer.android.com/training/implementing-navigation/ancestral.html#up

编辑

要实现您想要的效果，您必须实现自己的导航例程。

    mToolbar.setNavigationOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if(shouldBack()) {
               //call onbackpressed or something
                if(displayBackAgain)
                    return; //return after so you don't call syncState();       
            }else if (mNavigationDrawerFragment.isDrawerOpen())
                mNavigationDrawerFragment.closeDrawer();
            else
                mNavigationDrawerFragment.openDrawer();
            mNavigationDrawerFragment.getActionBarDrawerToggle().syncState();
        }
    });
}

要启用后退按钮图标，只需调用 getSupportActionBar().setDisplayHomeAsUpEnabled(true); 即可禁用它，只需调用 mNavigationDrawerFragment.getActionBarDrawerToggle().syncState();