当你在Fragments之间转换时，调用addToBackStack()作为FragmentTransaction的一部分:

FragmentTransaction tx = fragmentManager.beginTransation();
tx.replace( R.id.fragment, new MyFragment() ).addToBackStack( "tag" ).commit();

如果你需要更详细的控制(例如，当一些片段可见时，你想要抑制返回键)，你可以在你的片段的父视图上设置一个OnKeyListener:

//You need to add the following line for this solution to work; thanks skayred
fragment.getView().setFocusableInTouchMode(true);
fragment.getView().requestFocus();
fragment.getView().setOnKeyListener( new OnKeyListener()
{
    @Override
    public boolean onKey( View v, int keyCode, KeyEvent event )
    {
        if( keyCode == KeyEvent.KEYCODE_BACK )
        {
            return true;
        }
        return false;
    }
} );

在fragment类中，为back event放以下代码:

 rootView.setFocusableInTouchMode(true);
        rootView.requestFocus();
        rootView.setOnKeyListener( new OnKeyListener()
        {
            @Override
            public boolean onKey( View v, int keyCode, KeyEvent event )
            {
                if( keyCode == KeyEvent.KEYCODE_BACK )
                {
                    FragmentManager fragmentManager = getFragmentManager();
                    fragmentManager.beginTransaction()
                            .replace(R.id.frame_container, new Book_service_provider()).commit();

                    return true;
                }
                return false;
            }
        } );

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();
}

检查后台工作完美

@Override
public boolean onKeyDown(int keyCode, KeyEvent event)
{
    if (keyCode == KeyEvent.KEYCODE_BACK)
    {
        if (getFragmentManager().getBackStackEntryCount() == 1)
        {
            // DO something here since there is only one fragment left
            // Popping a dialog asking to quit the application
            return false;
        }
    }
    return super.onKeyDown(keyCode, event);
}

我宁愿这样做:

private final static String TAG_FRAGMENT = "TAG_FRAGMENT";

private void showFragment() {
    final Myfragment fragment = new MyFragment();
    final FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
    transaction.replace(R.id.fragment, fragment, TAG_FRAGMENT);
    transaction.addToBackStack(null);
    transaction.commit();
}

@Override
public void onBackPressed() {
    final Myfragment fragment = (Myfragment) getSupportFragmentManager().findFragmentByTag(TAG_FRAGMENT);

    if (fragment.allowBackPressed()) { // and then you define a method allowBackPressed with the logic to allow back pressed or not
        super.onBackPressed();
    }
}

 @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;
            }
        });
    }