Android设备Home、Menu和Back返回键的监听

在APP的操作中，有时需要监听系统按键，今天我就分享下自己的学习所得。

Menu键和Back键通过KeyDown事件就可以监听到，但Home键触发是系统事件，不能通过KeyDown简单的监控，但可以通过监听广播事件来处理。按下Home键后，Activity也会调用onUserLeaveHint 和 onSaveInstanceState 等函数，也可以在里面添加想要的处理程序。

代码很简单，分享如下：

package com.example.hornsey.myapplication.Demo;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyEvent;

import com.example.hornsey.myapplication.R;

public class KeyDownDemo extends Activity {

    private static final String TAG = "KeyDownDemo";
    private Context context;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_key_down_demo);

        context = KeyDownDemo.this;

        /*Home键是系统事件，只能通过广播监听*/
        IntentFilter filter = new IntentFilter(Intent.ACTION_CLOSE_SYSTEM_DIALOGS);
        registerReceiver(receiver, filter);
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        switch (keyCode) {
            case KeyEvent.KEYCODE_BACK:
                Log.d(TAG, "onKeyDown KEYCODE_BACK");
//                showDialog();
                break;
            /*
            * Home键是系统事件，不能通过KeyDown监听
            * 此处log不会打印
            */
            case KeyEvent.KEYCODE_HOME:
                Log.d(TAG, "onKeyDown KEYCODE_HOME");
                break;
            case KeyEvent.KEYCODE_MENU:
                Log.d(TAG, "onKeyDown KEYCODE_MENU");
                break;

        }
        return super.onKeyDown(keyCode, event);
    }

    protected void showDialog() {
        AlertDialog.Builder builder = new AlertDialog.Builder(context);
        builder.setTitle("系统提示");
        builder.setMessage("确定要退出吗?");
        builder.setPositiveButton("确认",
                new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.dismiss();
                        finish();
                    }
                });
        builder.setNegativeButton("取消",
                new android.content.DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.dismiss();
                    }
                });
        builder.create().show();
    }

    @Override
    protected void onUserLeaveHint() {
        Log.d(TAG, "onUserLeaveHint ");
        super.onUserLeaveHint();
    }

    @Override
    protected void onPause() {
        Log.d(TAG, "onPause ");
        super.onPause();
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        Log.d(TAG, "onSaveInstanceState ");
        super.onSaveInstanceState(outState);
    }

    @Override
    protected void onDestroy() {
        Log.d(TAG, "onDestroy ");
        unregisterReceiver(receiver);
        super.onDestroy();
    }

    /*
        *HomeKey监听事件广播接收器
        *
        */
    BroadcastReceiver receiver = new BroadcastReceiver(){

        @Override
        public void onReceive(Context context, Intent intent) {
            Log.d(TAG, "HomeKeyEventBroadcastReceiver.onReceive ");
        }
    };



}

在 依次按下Menu键，Home键，再通过Home键返回到应用，在按下Back键退出操作中，代码log如下：

11-06 14:25:32.401    5442-5442/com.example.hornsey.myapplication D/KeyDownDemo﹕ onKeyDown KEYCODE_MENU
11-06 14:25:32.471    5442-5442/com.example.hornsey.myapplication D/AbsListView﹕ Get MotionRecognitionManager
11-06 14:25:37.471    5442-5442/com.example.hornsey.myapplication D/KeyDownDemo﹕ HomeKeyEventBroadcastReceiver.onReceive
11-06 14:25:37.511    5442-5442/com.example.hornsey.myapplication D/KeyDownDemo﹕ onUserLeaveHint
11-06 14:25:37.511    5442-5442/com.example.hornsey.myapplication D/KeyDownDemo﹕ onPause
11-06 14:25:38.221    5442-5442/com.example.hornsey.myapplication D/KeyDownDemo﹕ onSaveInstanceState
11-06 14:25:42.961    5442-5442/com.example.hornsey.myapplication D/KeyDownDemo﹕ HomeKeyEventBroadcastReceiver.onReceive
11-06 14:25:43.051    5442-5442/com.example.hornsey.myapplication D/KeyDownDemo﹕ HomeKeyEventBroadcastReceiver.onReceive
11-06 14:25:46.401    5442-5442/com.example.hornsey.myapplication E/copybit﹕ Error opening frame buffer errno=13 (Permission denied)
11-06 14:25:46.401    5442-5442/com.example.hornsey.myapplication W/Adreno200-EGLSUB﹕ <updater_create_surface_state:342>: updater_create_surface_state failed to open copybit, error: -13
11-06 14:25:52.421    5442-5442/com.example.hornsey.myapplication D/KeyDownDemo﹕ onKeyDown KEYCODE_BACK
11-06 14:25:52.611    5442-5442/com.example.hornsey.myapplication D/KeyDownDemo﹕ onPause
11-06 14:25:53.041    5442-5442/com.example.hornsey.myapplication D/KeyDownDemo﹕ onDestroy

个人能力有限，不足之处，欢迎指正。