我正在开发一个 Android 项目，我需要检查何时按下空格键以便我可以执行某个功能。

问题是，它可以在模拟器上运行，但不能在我的实际设备上运行。我认为这可能是因为我的模拟器使用的是物理键盘，而不是屏幕上的虚拟键盘，但在实际设备上进行测试时，它使用的是虚拟键盘。

我正在尝试调度键事件

@Override
    public boolean dispatchKeyEvent(KeyEvent event)
    {
        
        if (event.getKeyCode() == KeyEvent.KEYCODE_SPACE
                && event.getAction() == KeyEvent.ACTION_UP)
        {
            QueryEditor queryEditor = (QueryEditor)getSupportFragmentManager().findFragmentById(R.id.fragment_queryEditor);
            queryEditor.formatQueryText();
            return true;
        }
        }

我也试过按下开键

@Override
    public boolean onKeyDown(int keyCode, KeyEvent event)
    {
        if (keyCode == KeyEvent.KEYCODE_BACK)
        {
            disconnectDatabase();
        }
        else if (keyCode == KeyEvent.KEYCODE_DEL)
        {
            QueryEditor queryEditor = (QueryEditor)getSupportFragmentManager().findFragmentById(R.id.fragment_queryEditor);
            queryEditor.formatQueryText();
        }
        
        return super.onKeyDown(keyCode, event);
    }

除非按下后退按钮，否则这些都不会被触发，但我需要空格键来触发事件。

更新

下面是我如何创建 QueryEditor Fragment 和创建事件处理程序的代码

@Override
    public void onActivityCreated(Bundle savedInstanceState)
    {
        super.onActivityCreated(savedInstanceState);
        
        iQueryEditor = (IQueryEditor)this;
        iErrorHandler = (IErrorHandler)this;
        
        txtQueryEditor = (EditText)getActivity().findViewById(R.id.query_txtQueryEditor);
        
        btnSubmitQuery = (ImageButton)getActivity().findViewById(R.id.query_btnPerformQuery);
        btnClearQuery = (ImageButton)getActivity().findViewById(R.id.query_btnDeleteQuery);
        
        txtQueryEditor.addTextChangedListener(new QueryTextChanged(getActivity(), txtQueryEditor, iQueryEditor));
        setDatabaseUsed();
        txtQueryEditor.setOnEditorActionListener(new OnEditorActionListener() {
            
            @Override
            public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
                if ((event != null && (event.getKeyCode() == KeyEvent.KEYCODE_ENTER))
                        || actionId == EditorInfo.IME_ACTION_DONE)
                {
                    executeQuery();
                    return true;
                }
                else if (event.getKeyCode() == KeyEvent.KEYCODE_SPACE && event.getAction() == KeyEvent.ACTION_UP)
                {
                    Toast.makeText(getActivity(), "Space Bar Pressed", Toast.LENGTH_SHORT).show();
                    return true;
                }
                return false;
            }
        });
        
        btnSubmitQuery.setOnClickListener(mBtnSubmitQueryListener);
        btnClearQuery.setOnClickListener(mBtnDeleteQueryListener);
    }

txtQueryEditor 是我尝试接收空格键事件的 EditText。

最佳答案

部分答案在于 KeyEvent API documentation :

As soft input methods can use multiple and inventive ways of inputting text, there is no guarantee that any key press on a soft keyboard will generate a key event: this is left to the IME's discretion, and in fact sending such events is discouraged. You should never rely on receiving KeyEvents for any key on a soft input method. In particular, the default software keyboard will never send any key event to any application targetting Jelly Bean or later, and will only send events for some presses of the delete and return keys to applications targetting Ice Cream Sandwich or earlier. Be aware that other software input methods may never send key events regardless of the version. Consider using editor actions like IME_ACTION_DONE if you need specific interaction with the software keyboard, as it gives more visibility to the user as to how your application will react to key presses.

这是一个comment由 Google 工程师留下:

The answer is quite simple. Applications should never rely on key events to manage user input. The reason for this is, it results in a very poor user experience.

To start with, there are too many cases where it does not work. It does not work appropriately for CJK languages. It does not work correctly with gesture input, or with voice input, or with toggle input, or any new inventive input method developers may come up with in the future. In fact, the only case where it works is for only restricted cases of the poorest input experience : a legacy hardware-keyboard-like input method, which is a poor fit for the mobile era.

This is why Android defines a rich API through which IMEs communicate to the applications. It is method agnostic and language agnostic, and all software input methods are implementing it. Applications are supposed to make use of this API, and using EditText is the simplest way of doing this (more on this below).

Please stop relying on legacy key events for text entry -- AT ALL. It is good to support them, but requiring them is bad for everyone. It breaks consistency, it locks some languages out of your app, and it forces users into a much poorer experience than they expect on Android. And as noted in comment #14, input methods are explicitly under no obligation at all to send key events, though some may choose to do it.

There are two simple ways of implementing the rich text input APIs. Both will require some of this is done in Java land. The first one is to simply use EditText. If your app needs to do its own rendering, you can either subclass it if that suits you, or make it hidden while you render any changes to the text. You could also use DynamicLayout and Editable to achieve the same effect. Another possibility is to implement directly the InputConnection API by extending BaseInputConnection, however this is a LOT of hard work and should generally only need to be done by applications that have very specific needs with regards to text edition, like an IDE or a word processor.

关于android - DispatchKeyEvent 监听空格键被按下，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/23618567/