Android - 将ActionBar返回按钮切换为导航按钮

对我来说，我想把Burger图标改成在Fragment的ActionBar左侧的返回箭头图标，因为我正在使用Navigation Drawer。同时在右侧添加一个菜单。

在Main Activity中，它已经被设置好了 - 默认情况下，当Android Studio为我创建导航抽屉时，就像这样：

Toolbar toolbar = findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
DrawerLayout drawer = findViewById(R.id.drawer_layout);
ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open,
                R.string.navigation_drawer_close);
drawer.addDrawerListener(toggle);
toggle.syncState();

在片段中（完整实现）：

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setHasOptionsMenu(true); // To show the menu options
}

@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState){
    super.onViewCreated(view, savedInstanceState);
    showActionBar(); // the method to change ActionBar
}

@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
    // inflate the customized menu which already created in XML
    getActivity().getMenuInflater().inflate(R.menu.fragment_menu, menu);
    super.onCreateOptionsMenu(menu, inflater);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // add implementation when user select an item from the menu
    switch (item.getItemId()) {
        case R.id.option1:
            // do something
            return true;
        case R.id.option2:
            // do something
            return true;
        case R.id.option3:
            // do something
            return true;
        default:
            return super.onOptionsItemSelected(item);
    }
}

private void showActionBar() {
    // get the ToolBar from Main Activity
    final Toolbar toolbar = getActivity().findViewById(R.id.toolbar);
    // get the ActionBar from Main Activity
    final ActionBar actionBar = ((AppCompatActivity)getActivity()).getSupportActionBar();
    // inflate the customized Action Bar View
    LayoutInflater inflater = (LayoutInflater) getActivity()
            .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    View v = inflater.inflate(R.layout.fragment_actionbar, null);

    if (actionBar != null) {
        // enable the customized view and disable title
        actionBar.setDisplayShowCustomEnabled(true);
        actionBar.setDisplayShowTitleEnabled(false);

        actionBar.setCustomView(v);
        // remove Burger Icon
        toolbar.setNavigationIcon(null);

        // add click listener to the back arrow icon
        v.findViewById(R.id.back).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                // reverse back the show
                actionBar.setDisplayShowCustomEnabled(false);
                actionBar.setDisplayShowTitleEnabled(true);
                //get the Drawer and DrawerToggle from Main Activity
                // set them back as normal
                DrawerLayout drawer = getActivity().findViewById(R.id.drawer_layout);
                ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                        getActivity(), drawer, toolbar, R.string.navigation_drawer_open,
                        R.string.navigation_drawer_close);
                // All that to re-synchronize the Drawer State
                toggle.syncState();
                // Implement Back Arrow Icon 
                // so it goes back to previous Fragment
                getActivity().onBackPressed();
            }
        });
    }
}

fragment_actionbar.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="match_parent"
    android:layout_gravity="fill_horizontal" >

    <ImageView
        android:id="@+id/back"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:src="@drawable/ic_menu_back"
        android:layout_marginLeft="@dimen/_5sdp"
        android:layout_alignParentStart="true"
        android:layout_marginStart="@dimen/_5sdp" />

</RelativeLayout>

ic_menu_back.xml

<vector xmlns:android="http://schemas.android.com/apk/res/android"
    android:width="24dp"
    android:height="24dp"
    android:viewportHeight="459"
    android:viewportWidth="459">
    <path
        android:fillColor="#ffffff"
        android:pathData="M178.5,140.25v-102L0,216.75l178.5,178.5V290.7c127.5,0,216.75,40.8,280.5,130.05C433.5,293.25,357,165.75,178.5,140.25z"/>
</vector>

fragment_menu.xml

<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:background="@drawable/border_shadow">

    <item
        android:id="@+id/option1"
        android:title="@string/show_profile"
        app:showAsAction="never"/>
    <item
        android:id="@+id/option2"
        android:title="@string/report_pic"
        app:showAsAction="never"/>
    <item
        android:id="@+id/option3"
        android:title="@string/delete_pic"
        app:showAsAction="never"/>
</menu>

我为Kotlin开发者提供了最简单的解决方案

只需在根活动中添加此代码，即可解决片段阻力问题

if (supportFragmentManager.backStackEntryCount > 0) {
  supportActionBar!!.setDisplayHomeAsUpEnabled(true)
  toolbar.setNavigationOnClickListener {
      if (supportFragmentManager.backStackEntryCount > 0) {
          super.onBackPressed()
      } else {
          supportActionBar!!.setDisplayHomeAsUpEnabled(false)
          drawerLayout.addDrawerListener(toggle)
          toggle.syncState()
          drawerLayout.openDrawer(GravityCompat.START)
      }
  }
} else {
  supportActionBar!!.setDisplayHomeAsUpEnabled(false)
  drawerLayout.addDrawerListener(toggle)
  toggle.syncState()
}

在这里，每当设置 setDisplayHomeAsUpEnabled 为 true 时，我会显示返回按钮。点击它时，我会调用 super.onBackPressed()，这类似于您的返回按钮所做的操作！

(activity as MainActivity).supportActionBar?.setHomeAsUpIndicator(R.drawable.ic_arrow_back)