如果你重写了片段视图的onKey方法，你需要:

    view.setFocusableInTouchMode(true);
    view.requestFocus();
    view.setOnKeyListener(new View.OnKeyListener() {
            @Override
            public boolean onKey(View v, int keyCode, KeyEvent event) {
                Log.i(tag, "keyCode: " + keyCode);
                if( keyCode == KeyEvent.KEYCODE_BACK && event.getAction() == KeyEvent.ACTION_UP) {
                    Log.i(tag, "onKey Back listener is working!!!");
                    getFragmentManager().popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
                    return true;
                } 
                return false;
            }
        });

 @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;
            }
        });
    }

如果你想处理硬件返回键事件，那么你必须在Fragment的onActivityCreated()方法中执行以下代码。

你还需要检查Action_Down或Action_UP事件。如果你不检查，那么onKey()方法将调用2次。

同样，如果你的rootview(getView())将不包含焦点，那么它将无法工作。如果你点击了任何控件，那么你需要再次使用getView().requestFocus()给rootview的焦点;在此之后，只有onKeydown()将调用。

getView().setFocusableInTouchMode(true);
getView().requestFocus();

getView().setOnKeyListener(new OnKeyListener() {
        @Override
        public boolean onKey(View v, int keyCode, KeyEvent event) {
                if (event.getAction() == KeyEvent.ACTION_DOWN) {
                    if (keyCode == KeyEvent.KEYCODE_BACK) {
                        Toast.makeText(getActivity(), "Back Pressed", Toast.LENGTH_SHORT).show();
                    return true;
                    }
                }
                return false;
            }
        });

对我来说很好。

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();
}

工作代码:

package com.example.keralapolice;

import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentManager.OnBackStackChangedListener;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.Gravity;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Toast;

public class ChiefFragment extends Fragment {
    View view;

    // public OnBackPressedListener onBackPressedListener;

    @Override
    public View onCreateView(LayoutInflater inflater,
            ViewGroup container, Bundle args) {

        view = inflater.inflate(R.layout.activity_chief, container, false);
        getActivity().getActionBar().hide();
        view.setFocusableInTouchMode(true);
        view.requestFocus();
        view.setOnKeyListener(new View.OnKeyListener() {
            @Override
            public boolean onKey(View v, int keyCode, KeyEvent event) {
                Log.i(getTag(), "keyCode: " + keyCode);
                if (keyCode == KeyEvent.KEYCODE_BACK) {
                    getActivity().getActionBar().show();
                    Log.i(getTag(), "onKey Back listener is working!!!");
                    getFragmentManager().popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE);
                    // String cameback="CameBack";
                    Intent i = new Intent(getActivity(), home.class);
                    // i.putExtra("Comingback", cameback);
                    startActivity(i);
                    return true;
                } else {
                    return false;
                }
            }
        });
        return view;
    }
}

如果你正在使用FragmentActivity。然后像这样做

首先在你的碎片中调用这个。

public void callParentMethod(){
    getActivity().onBackPressed();
}

然后调用你的父类FragmentActivity中的onBackPressed方法。

@Override
public void onBackPressed() {
  //super.onBackPressed();
  //create a dialog to ask yes no question whether or not the user wants to exit
  ...
}