Android 返回键方法

1、都是按下返回鍵触发，调用父类方法会直接关闭调当前activity

2、先后调用顺序onKeyDown>onBackPressed

3、dispatchKeyEvent优先级最高，且上面两个方法不会调用

 @Override
    public void onBackPressed(){
        super.onBackPressed();
        Log.i("adam","已退出");
    }
    //都是按下返回鍵触发，调用父类方法会直接关闭调当前activity
    //先后调用顺序onKeyDown>onBackPressed
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if ((keyCode == KeyEvent.KEYCODE_BACK)) {
            Toast.makeText(this, "按下了back键 onKeyDown()", Toast.LENGTH_SHORT).show();
            Log.i("adam","onKeyDown已退出");
            return super.onKeyDown(keyCode, event);
        }else {
            Log.i("adam","true");
            return false;
        }
    }
    //优先级最高，且上面两个方法不会调用
    @Override
    public boolean dispatchKeyEvent(KeyEvent keyEvent) {
        if (keyEvent.getKeyCode() == 4 && keyEvent.getAction() == 0 && keyEvent.getRepeatCount() == 0) {
            Log.i("adam","dispatchKeyEvent已退出");
        }
        return false;
    }

4、新建一个退出对话框

   public void adamExit(){
        // 仅供参考
        AlertDialog.Builder builder = new AlertDialog.Builder(MainActivity.this);
        builder.setMessage("确认退出游戏吗？").setNegativeButton("取消", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                Toast.makeText(MainActivity.this, "取消退出", Toast.LENGTH_LONG).show();
                //关闭对话框
                dialog.dismiss();
            }
        }).setPositiveButton("确认退出", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                //手动杀死进程
                Intent intent = new Intent(Intent.ACTION_MAIN);
                intent.addCategory(Intent.CATEGORY_HOME);
                intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                startActivity(intent);
                MainActivity.this.finish();
                android.os.Process.killProcess(android.os.Process.myPid());
            }
        }).show();
    }