抽屉布局未按下后关闭(取决于support-v4 lib)

Question

我正在关注创建导航抽屉教程(Android培训).

我已经下载了示例应用程序,它按预期工作.我打开抽屉,向后按,它就会关闭.

当我用我lib/android-support-v4.jar的更新版本(版本20)替换(最初大小为523 KB)Android-SDK/extras/android/support/v4/android-support-v4.jar(大小为741 KB)时出现问题.更换后,如果我打开抽屉然后按下设备的后退按钮,应用程序将关闭而不是关闭抽屉.

我怎么解决这个问题？我应该保留旧的android-support-v4.jar版本,还是应该在需要时以编程方式拦截关闭抽屉的后退按钮？

更新:我继续测试问题,为此我在AndroidStudio中构建了项目.复制示例应用程序(src,res并更新清单)之后运行它:即使DrawerLayout打开,后退按钮也会关闭应用程序.然后我修改了build.gradle文件更改行:

compile 'com.android.support:appcompat-v7:20.0.0'

同

compile 'com.android.support:appcompat-v7:19.0.0'

问题消失了:后退按钮首先关闭抽屉,然后关闭应用程序

活动的完整代码(链接到Android培训源代码):

public class MainActivity extends Activity {
    private DrawerLayout mDrawerLayout;
    private ListView mDrawerList;
    private ActionBarDrawerToggle mDrawerToggle;

    private CharSequence mDrawerTitle;
    private CharSequence mTitle;
    private String[] mPlanetTitles;

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

        mTitle = mDrawerTitle = getTitle();
        mPlanetTitles = getResources().getStringArray(R.array.planets_array);
        mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
        mDrawerList = (ListView) findViewById(R.id.left_drawer);

        // set a custom shadow that overlays the main content when the drawer opens
        mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
        // set up the drawer's list view with items and click listener
        mDrawerList.setAdapter(new ArrayAdapter<String>(this,
                R.layout.drawer_list_item, mPlanetTitles));
        mDrawerList.setOnItemClickListener(new DrawerItemClickListener());

        // enable ActionBar app icon to behave as action to toggle nav drawer
        getActionBar().setDisplayHomeAsUpEnabled(true);
        getActionBar().setHomeButtonEnabled(true);

        // ActionBarDrawerToggle ties together the the proper interactions
        // between the sliding drawer and the action bar app icon
        mDrawerToggle = new ActionBarDrawerToggle(
                this,                  /* host Activity */
                mDrawerLayout,         /* DrawerLayout object */
                R.drawable.ic_drawer,  /* nav drawer image to replace 'Up' caret */
                R.string.drawer_open,  /* "open drawer" description for accessibility */
                R.string.drawer_close  /* "close drawer" description for accessibility */
                ) {
            public void onDrawerClosed(View view) {
                getActionBar().setTitle(mTitle);
                //supportInvalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
            }

            public void onDrawerOpened(View drawerView) {
                getActionBar().setTitle(mDrawerTitle);
                //supportInvalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
            }
        };
        mDrawerLayout.setDrawerListener(mDrawerToggle);

        if (savedInstanceState == null) {
            selectItem(0);
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.main, menu);
        return super.onCreateOptionsMenu(menu);
    }

    /* Called whenever we call invalidateOptionsMenu() */
    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {
        // If the nav drawer is open, hide action items related to the content view
        boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);
        menu.findItem(R.id.action_websearch).setVisible(!drawerOpen);
        return super.onPrepareOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
         // The action bar home/up action should open or close the drawer.
         // ActionBarDrawerToggle will take care of this.
        if (mDrawerToggle.onOptionsItemSelected(item)) {
            return true;
        }
        // Handle action buttons
        switch(item.getItemId()) {
        case R.id.action_websearch:
            // create intent to perform web search for this planet
            Intent intent = new Intent(Intent.ACTION_WEB_SEARCH);
            intent.putExtra(SearchManager.QUERY, getActionBar().getTitle());
            // catch event that there's no activity to handle intent
            if (intent.resolveActivity(getPackageManager()) != null) {
                startActivity(intent);
            } else {
                Toast.makeText(this, R.string.app_not_available, Toast.LENGTH_LONG).show();
            }
            return true;
        default:
            return super.onOptionsItemSelected(item);
        }
    }

    /* The click listner for ListView in the navigation drawer */
    private class DrawerItemClickListener implements ListView.OnItemClickListener {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            selectItem(position);
        }
    }

    private void selectItem(int position) {
        // update the main content by replacing fragments
        Fragment fragment = new PlanetFragment();
        Bundle args = new Bundle();
        args.putInt(PlanetFragment.ARG_PLANET_NUMBER, position);
        fragment.setArguments(args);

        FragmentManager fragmentManager = getFragmentManager();
        fragmentManager.beginTransaction().replace(R.id.content_frame, fragment).commit();

        // update selected item and title, then close the drawer
        mDrawerList.setItemChecked(position, true);
        setTitle(mPlanetTitles[position]);
        mDrawerLayout.closeDrawer(mDrawerList);
    }

    @Override
    public void setTitle(CharSequence title) {
        mTitle = title;
        getActionBar().setTitle(mTitle);
    }

    /**
     * When using the ActionBarDrawerToggle, you must call it during
     * onPostCreate() and onConfigurationChanged()...
     */

    @Override
    protected void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);
        // Sync the toggle state after onRestoreInstanceState has occurred.
        mDrawerToggle.syncState();
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        // Pass any configuration change to the drawer toggls
        mDrawerToggle.onConfigurationChanged(newConfig);
    }

    /**
     * Fragment that appears in the "content_frame", shows a planet
     */
    public static class PlanetFragment extends Fragment {
        public static final String ARG_PLANET_NUMBER = "planet_number";

        public PlanetFragment() {
            // Empty constructor required for fragment subclasses
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_planet, container, false);
            int i = getArguments().getInt(ARG_PLANET_NUMBER);
            String planet = getResources().getStringArray(R.array.planets_array)[i];

            int imageId = getResources().getIdentifier(planet.toLowerCase(Locale.getDefault()),
                            "drawable", getActivity().getPackageName());
            ((ImageView) rootView.findViewById(R.id.image)).setImageResource(imageId);
            getActivity().setTitle(planet);
            return rootView;
        }
    }
}

Answer 1

将支持库升级到20.0.0后,我遇到了完全相同的问题.

添加下面一行代码可以解决我的问题.(onCreate in my activitiy)

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

    mDrawerLayout = (DrawerLayout) this.findViewById(R.id.drawer_layout);
    mDrawerLayout.setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS); /* add this line */

    ....
}

Answer 2

这是您的问题的快速解决方案.只需覆盖onBackPressed()Activity/Fragment中的方法:

@Override
public void onBackPressed()
{
    if (mDrawerLayout.isDrawerOpen(Gravity.START))
        mDrawerLayout.closeDrawer(Gravity.START);
    else
        super.onBackPressed();
}

使用Gravity.START左抽屉,Gravity.END为正确的

Answer 3

在setUpNavDrawer中

mDrawerLayout.setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS);

也

@Override
public void onBackPressed()
{
  if (mDrawerLayout.isOpen())
    mDrawerLayout.close();
  else
    super.onBackPressed();
}