我认为最简单的方法是创建一个接口，并在Activity中检查片段是否属于接口类型，如果是，则调用它的方法来处理弹出。下面是要在片段中实现的接口。

public interface BackPressedFragment {

    // Note for this to work, name AND tag must be set anytime the fragment is added to back stack, e.g.
    // getActivity().getSupportFragmentManager().beginTransaction()
    //                .replace(R.id.fragment_container, MyFragment.newInstance(), "MY_FRAG_TAG")
    //                .addToBackStack("MY_FRAG_TAG")
    //                .commit();
    // This is really an override. Should call popBackStack itself.
    void onPopBackStack();
}

下面是如何实现它。

public class MyFragment extends Fragment implements BackPressedFragment
    @Override
    public void onPopBackStack() {
        /* Your code goes here, do anything you want. */
        getActivity().getSupportFragmentManager().popBackStack();
}

在你的Activity中，当你处理弹出时(可能在onBackPressed和onOptionsItemSelected中)，使用这个方法弹出backstack:

public void popBackStack() {
    FragmentManager fm = getSupportFragmentManager();
    // Call current fragment's onPopBackStack if it has one.
    String fragmentTag = fm.getBackStackEntryAt(fm.getBackStackEntryCount() - 1).getName();
    Fragment currentFragment = getSupportFragmentManager().findFragmentByTag(fragmentTag);
    if (currentFragment instanceof BackPressedFragment)
        ((BackPressedFragment)currentFragment).onPopBackStack();
    else
        fm.popBackStack();
}

在您的活动中添加此代码

@Override

public void onBackPressed() {
    if (getFragmentManager().getBackStackEntryCount() == 0) {
        super.onBackPressed();
    } else {
        getFragmentManager().popBackStack();
    }
}

并在commit()之前在Fragment中添加这一行

ft.addToBackStack(任何名称);

使用addToBackStack方法替换一个片段:

getFragmentManager().beginTransaction().replace(R.id.content_frame, fragment).addToBackStack("my_fragment").commit();

然后在您的活动中，使用以下代码从一个片段返回到另一个片段(前一个片段)。

@Override
public void onBackPressed() {
    if (getParentFragmentManager().getBackStackEntryCount() > 0) {
        getParentFragmentManager().popBackStack();
    } else {
        super.onBackPressed();
    }
}

如果您管理将每个事务添加到后退堆栈的流程，那么您可以这样做，以便在用户按后退按钮时显示上一个片段(您也可以映射home按钮)。

@Override
public void onBackPressed() {
    if (getFragmentManager().getBackStackEntryCount() > 0)
        getFragmentManager().popBackStack();
    else
        super.onBackPressed();
}

我认为最简单的方法是创建一个接口，并在Activity中检查片段是否属于接口类型，如果是，则调用它的方法来处理弹出。下面是要在片段中实现的接口。

public interface BackPressedFragment {

    // Note for this to work, name AND tag must be set anytime the fragment is added to back stack, e.g.
    // getActivity().getSupportFragmentManager().beginTransaction()
    //                .replace(R.id.fragment_container, MyFragment.newInstance(), "MY_FRAG_TAG")
    //                .addToBackStack("MY_FRAG_TAG")
    //                .commit();
    // This is really an override. Should call popBackStack itself.
    void onPopBackStack();
}

下面是如何实现它。

public class MyFragment extends Fragment implements BackPressedFragment
    @Override
    public void onPopBackStack() {
        /* Your code goes here, do anything you want. */
        getActivity().getSupportFragmentManager().popBackStack();
}

在你的Activity中，当你处理弹出时(可能在onBackPressed和onOptionsItemSelected中)，使用这个方法弹出backstack:

public void popBackStack() {
    FragmentManager fm = getSupportFragmentManager();
    // Call current fragment's onPopBackStack if it has one.
    String fragmentTag = fm.getBackStackEntryAt(fm.getBackStackEntryCount() - 1).getName();
    Fragment currentFragment = getSupportFragmentManager().findFragmentByTag(fragmentTag);
    if (currentFragment instanceof BackPressedFragment)
        ((BackPressedFragment)currentFragment).onPopBackStack();
    else
        fm.popBackStack();
}

 @Override
    public void onResume() {

        super.onResume();

        getView().setFocusableInTouchMode(true);
        getView().requestFocus();
        getView().setOnKeyListener(new View.OnKeyListener() {
            @Override
            public boolean onKey(View v, int keyCode, KeyEvent event) {

                if (event.getAction() == KeyEvent.ACTION_UP && keyCode == KeyEvent.KEYCODE_BACK){

                    if (mDrawerLayout.isDrawerOpen(GravityCompat.START)){
                        mDrawerLayout.closeDrawer(GravityCompat.START);
                    }
                    return true;
                }

                return false;
            }
        });
    }