java - 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 fragment 。 Drawer navigation

在主页 fragment 中，我显示不同的类别(那些彩色框)，当我选择一个类别时，它会显示新 fragment ，其中包含该类别的日常和一般详细信息。(我们称之为详细信息 fragment )Home fragment

我想要但无法弄清楚如何完成，是在那个详细信息 fragment 中，我希望有返回箭头将我带回主页 fragment ，而不是打开抽屉导航的汉堡菜单图标。 Detail fragment

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(著名的遗言)。

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，并使用 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。