如何覆盖抽屉导航按钮行为并更改图标？

Question

我有一个应用程序，它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Home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，它会显示包含该类别的每日和一般详细信息的新片段。（让我们称之为详细片段）Home片段

我想要的，但不知道如何完成的，是在细节片段中，我希望有带我回到主页片段的返回箭头，而不是打开抽屉导航的汉堡菜单图标。细节片段

Answer 1

谢谢你的帮助，我从你的答案和Stackoverflow的其他帖子中得到了一些想法。如果你认为这是一个糟糕的解决方案，请让我知道。这就是我如何使用非常简单的解决方案（Kotlin）使其工作的原因：

把这个放到你的activitys onCreate中

supportFragmentManager.addOnBackStackChangedListener {
       actionBarDrawerToggle?.isDrawerIndicatorEnabled = supportFragmentManager.backStackEntryCount <= 0
}

并覆盖onSupport portNavigate Up（）：

override fun onSupportNavigateUp(): Boolean {
    supportFragmentManager.popBackStack()
    return super.onSupportNavigateUp()
}

Answer 2

您可以通过将工具栏动态添加到主活动中来实现，而不是使用内置的导航抽屉，从头开始。添加片段时，请在片段上添加工具栏。工具栏myChildToolbar=（Toolbar）findViewById（R.id.my\u child\u Toolbar）；设置支持操作栏（myChildToolbar）；

// Get a support ActionBar corresponding to this toolbar
ActionBar ab = getSupportActionBar();

// Enable the Up button
ab.setDisplayHomeAsUpEnabled(true);

然后，您将能够覆盖按钮导航上的方法向上方法，以启用工具栏上所需的后退按钮。

Answer 3

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（著名的遗言）。

导入android。支持v7.app。ActionBarDrawerToggle导入android。支持v4.widget。抽屉布局

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.setDrawerIndicatorEngic来切换汉堡包图标的可见性，并使用ActionBar.setDisplayHomeAsUpEngic来切换Up按钮的可见性，基本上利用了它们各自的可绘制资源。