如何覆盖抽屉导航按钮行为并更改图标？

Question

我的应用程序使用抽屉导航来显示具有主要主题的不同片段。抽屉导航在“主页”片段中，我显示不同的类别（那些彩色框），当我选择一个类别时，它会显示带有该类别的日常和一般详细信息的新片段。（我们称之为“详细信息片段” ）我想要但无法弄清楚如何完成的是在该详细信息片段中，我希望有返回箭头将我带回主页片段，而不是打开抽屉导航的汉堡菜单图标。 细节片段

Answer 1

如果我假设您在布局中使用 android.support.v4.widget.DrawerLayout，那么这种方法可能适合您；我只在 API 21 上进行了测试，但考虑到它主要使用支持库，它应该可以在较低或较高的目标上工作（著名的最后一句话）。

导入 android.support.v7.app.ActionBarDrawerToggle 导入 android.support.v4.widget.DrawerLayout

ActionBarDrawerToggle mDrawerToggle;

DrawerLayout drawerLayout;

private boolean mToolBarNavigationListenerIsRegistered = false;

@Override

protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);

    setSupportActionBar(mToolbar);

    getSupportActionBar().setDisplayShowTitleEnabled(false);

    // Get DrawerLayout ref from layout

    drawerLayout = (DrawerLayout)findViewById(R.id.drawer);

    // Initialize ActionBarDrawerToggle, which will control toggle of hamburger.

    // You set the values of R.string.open and R.string.close accordingly.

    // Also, you can implement drawer toggle listener if you want.

    mDrawerToggle = new ActionBarDrawerToggle (this, drawerLayout, mToolbar, R.string.open, R.string.close);

    // Setting the actionbarToggle to drawer layout

    drawerLayout.setDrawerListener(mDrawerToggle);

    // Calling sync state is necessary to show your hamburger icon...

    // or so I hear. Doesn't hurt including it even if you find it works

    // without it on your test device(s)

    mDrawerToggle.syncState();

}

/**

 * To be semantically or contextually correct, maybe change the name

 * and signature of this function to something like:

 *

 * private void showBackButton(boolean show)

 * Just a suggestion.

 */

 private void enableViews(boolean enable) {

    // To keep states of ActionBar and ActionBarDrawerToggle synchronized,

    // when you enable on one, you disable on the other.

    // And as you may notice, the order for this operation is disable first, then enable - VERY VERY IMPORTANT.

    if(enable) {

        //You may not want to open the drawer on swipe from the left in this case  

        drawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_LOCKED_CLOSED);

        // Remove hamburger

        mDrawerToggle.setDrawerIndicatorEnabled(false);

        // Show back button

        getSupportActionBar().setDisplayHomeAsUpEnabled(true);

        // when DrawerToggle is disabled i.e. setDrawerIndicatorEnabled(false), navigation icon

        // clicks are disabled i.e. the UP button will not work.

        // We need to add a listener, as in below, so DrawerToggle will forward

        // click events to this listener.

        if(!mToolBarNavigationListenerIsRegistered) {

            mDrawerToggle.setToolbarNavigationClickListener(new View.OnClickListener() {

                @Override

                public void onClick(View v) {

                    // Doesn't have to be onBackPressed

                    onBackPressed();

                }

            });

            mToolBarNavigationListenerIsRegistered = true;

        }

    } else {

        //You must regain the power of swipe for the drawer. 

        drawerLayout.setDrawerLockMode(DrawerLayout.LOCK_MODE_UNLOCKED);

        // Remove back button

        getSupportActionBar().setDisplayHomeAsUpEnabled(false);

        // Show hamburger 

        mDrawerToggle.setDrawerIndicatorEnabled(true);

        // Remove the/any drawer toggle listener

        mDrawerToggle.setToolbarNavigationClickListener(null);

        mToolBarNavigationListenerIsRegistered = false;

    }

    // So, one may think "Hmm why not simplify to:

    // .....

    // getSupportActionBar().setDisplayHomeAsUpEnabled(enable);

    // mDrawer.setDrawerIndicatorEnabled(!enable);

    // ......

    // To re-iterate, the order in which you enable and disable views IS important #dontSimplify.

}

该解决方案使用 ActionBarDrawerToggle.setDrawerIndicatorEnabled 来切换汉堡包图标的可见性，使用 ActionBar.setDisplayHomeAsUpEnabled 来切换向上按钮的可见性，本质上是利用它们各自的可绘制资源。

Answer 2

如果您认为这是不好的解决方案，请告诉我。这就是我能够使用非常简单的解决方案（Kotlin）使其工作的方法：

将其放入您的活动 onCreate 中

supportFragmentManager.addOnBackStackChangedListener {

       actionBarDrawerToggle?.isDrawerIndicatorEnabled = supportFragmentManager.backStackEntryCount <= 0

}

并重写 onSupportNavigateUp()：

override fun onSupportNavigateUp(): Boolean {

    supportFragmentManager.popBackStack()

    return super.onSupportNavigateUp()

}

Answer 3

您可以通过动态地将工具栏添加到主活动来完成此操作，而不是使用内置的导航抽屉，从头开始制作。添加片段时在片段上添加工具栏。工具栏 myChildToolbar = (工具栏) findViewById(R.id.my_child_toolbar); setSupportActionBar(myChildToolbar);

// Get a support ActionBar corresponding to this toolbar

ActionBar ab = getSupportActionBar();

// Enable the Up button

ab.setDisplayHomeAsUpEnabled(true);

然后，您将能够重写按钮导航向上方法上的方法，以在工具栏上启用您想要的后退按钮。