抽屉式布局返回箭头功能

Question

我已经成功确定，在NavDrawer中更改汉堡和箭头图标，需要切换此代码：

mDrawerToggle.syncState();

然而，当我点击返回按钮时，它仍然打开导航抽屉菜单，实际上我想返回到之前的活动。我知道我可以简单地设置一个onClick监听器，但我认为Android有一种更本地的方法来导航到先前的屏幕。这是我的代码：' onCreate:

    mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
    mDrawerToggle = new ActionBarDrawerToggle(
            this,                  /* host Activity */
            mDrawerLayout,         /* DrawerLayout object */
            toolbar,  /* nav drawer icon to replace 'Up' caret */
            R.string.drawer_open,  /* "open drawer" description */
            R.string.drawer_close  /* "close drawer" description */
    ) {

        /**
         * Called when a drawer has settled in a completely closed state.
         */
        public void onDrawerClosed(View view) {
            super.onDrawerClosed(view);
            isOpen = false;
        }

        /**
         * Called when a drawer has settled in a completely open state.
         */
        public void onDrawerOpened(View drawerView) {
            super.onDrawerOpened(drawerView);
            isOpen = true;
        }
    };
    mDrawerToggle.setToolbarNavigationClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            onBackPressed();
        }
    });
    mDrawerToggle.setDrawerIndicatorEnabled(false);
    mDrawerLayout.addDrawerListener(mDrawerToggle);

    mDrawerList = (ListView) findViewById(R.id.left_drawer);
    ArrayList<String> drawerTitleArray = new ArrayList<>();
    drawerTitleArray.add(0, "TEST");
    drawerTitleArray.add(1, "TEST 1");
    // Set the adapter for the list view
    mDrawerList.setAdapter(new ArrayAdapter<String>(this,
            R.layout.drawer_list_item, drawerTitleArray));


       // TODO: Add Fragment Code to check if savedInstanceState ==                                 null; add at Activity Level?
    // Check that the activity is using the layout version with
    // the fragment_container FrameLayout


    //set up viewpager for current day
    //mPager = (ViewPager)               findViewById(R.id.home_polls_viewpager_fragment_container);
    //mPagerAdapter = new ScreenSlidePagerAdapter(getSupportFragmentManager());
    //mPager.setAdapter(mPagerAdapter);


    //get current date to apply to Viewpager
    mDateFormat = new SimpleDateFormat("MM-dd-yyyy");
    mDate = new Date();
    mCurrentDateString = mDateFormat.format(mDate);
    mViewPager = (ViewPager) findViewById(R.id.poll_fragment_container);
    mViewPager.setAdapter(new SectionPagerAdapter(getSupportFragmentManager()));
    mTabLayout.setupWithViewPager(mViewPager);

    // TODO: Checkn if AuthStateListenerNecessary
    //Determine whether necessary to use an AuthStateListener here
    // mUserRef.addAuthStateListener(new Firebase.AuthStateListener() {
    //@Override
    //public void onAuthStateChanged(AuthData authData) {
    //if (authData == null) {
    //Intent backToSignIn = new Intent(getApplication(),       SignupActivity.class);
    //startActivity(backToSignIn);
    //                    finish();
    //                }
    //            }
    //        })




}

@Override
protected void onStart() {
    super.onStart();

    v = new ValueEventListener() {
        //testing methodology of adding children
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            int pollsAvailable = (int) dataSnapshot.child(mCurrentDateString).getChildrenCount();
       //                mPagerAdapter.setPollsAvailable(pollsAvailable);
            Log.i("TAG", "There are " + String.valueOf(pollsAvailable) + " children in today's poll count.");
        }

        @Override
        public void onCancelled(FirebaseError firebaseError) {

        }
    };

    mPollsRef.addValueEventListener(v);

}

@Override
protected void onStop() {
    super.onStop();
    mPollsRef.removeEventListener(v);

}

@Override
public void onFragmentInteraction(Uri uri) {

}

@Override
public boolean onOptionsItemSelected(MenuItem item){
    if (item.getItemId() == android.R.id.home){
        super.onBackPressed();
        return true;}
    else
        return mDrawerToggle.onOptionsItemSelected(item) || super.onOptionsItemSelected(item);
}



@Override
protected void onPostCreate(Bundle savedInstanceState) {
    super.onPostCreate(savedInstanceState);
    //TODO: Be sure to only allow one instance of each activity
    //TODO:Address mDrawerToggle code from StackOverflow to make sure I am correctly implementing the return to previous activity
    // Sync the toggle state after onRestoreInstanceState has occurred.
    //        mDrawerToggle.syncState();
}

@Override
public void onConfigurationChanged(Configuration newConfig) {
    super.onConfigurationChanged(newConfig);
    mDrawerToggle.onConfigurationChanged(newConfig);
}

public class SectionPagerAdapter extends FragmentPagerAdapter {

    public SectionPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        int pollIndex = mIntentFromTouch.getIntExtra("Poll_Index",0);
        switch (position) {
            case 0:
                PollFragment pollFragment = PollFragment.newInstance(pollIndex);
                return pollFragment;
            case 1:
                DiscussionFragment discussionFragment = DiscussionFragment.newInstance(pollIndex);
                return discussionFragment;
            default:
                return new PollFragment();
        }
    }

    @Override
    public int getCount() {
        return 2;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        switch (position) {
            case 0:
                return getResources().getString(R.string.poll_text);
            case 1:
                return getResources().getString(R.string.discussion_text);
            default:
                return getResources().getString(R.string.poll_text);
        }
      }
   }


 }

- tccpg288

Answer 1

实际上，syncState()方法确保切换的图像与抽屉匹配，并在Toolbar/ActionBar上设置图像。它不会切换抽屉/返回功能。 setDrawerIndicatorEnabled() 方法是你要找的。当启用指示器时，切换操作抽屉。当禁用时，如果已设置，则回退到导航OnClickListener。

要处理返回功能，请将以下内容添加到切换的设置中：

mDrawerToggle.setHomeAsUpIndicator(R.drawable.abc_ic_ab_back_mtrl_am_alpha);
mDrawerToggle.setToolbarNavigationClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            onBackPressed();
        }
    }
);

然后，当您想禁用抽屉操作并允许单击切换返回时，只需调用以下命令：

mDrawerToggle.setDrawerIndicatorEnabled(false);

我还要指出的是，由于您使用了带有Toolbar参数的ActionBarDrawerToggle构造函数，因此在单击切换时不会调用Activity的onOptionsItemSelected()方法，并且不需要mDrawerToggle.onOptionsItemSelected(item)的调用。

注意：根据您使用的支持库版本，返回箭头Drawable资源的名称可能是R.drawable.abc_ic_ab_back_material。请参阅此帖子了解更多信息。

- Mike M.

---

谢谢！我会试一下。这个drawable包含在Android SDK中吗？ - tccpg288

它已经包含在支持库中。 - Mike M.

哦，实际上，根据库的版本不同，它可能会有不同的名称：R.drawable.abc_ic_ab_back_material。请参考这篇帖子。我马上会在这里修改我的答案。 - Mike M.

请澄清一下，我应该实现syncState()方法吗？还是它会认识到我没有使用NavDrawer的状态？ - tccpg288

没问题，只要对你有效就好了。根据您的其余设置，您可能根本不需要设置那个可绘制项。我只是将其包含为通用方法。不过，看起来您根本不需要 ActionBarDrawerToggle，因为您立即禁用了指示器。这就是我在之前的评论中询问的原因。ActionBarDrawerToggle 的特定用途是控制抽屉。如果您只想通过拖动来使用抽屉，则不需要切换开关。您可以直接设置该按钮返回。 - Mike M.