从软键盘截取后退按钮

onKeyDown() 和 onBackPressed() 不适用于这种情况。您必须使用 onKeyPreIme。

最初，您必须创建扩展 EditText 的自定义编辑文本。然后你必须实现控制 KeyEvent.KEYCODE_BACK 的 onKeyPreIme 方法。在此之后，一个背压足以解决您的问题。这个解决方案非常适合我。

CustomEditText.java

public class CustomEditText extends EditText {

    public CustomEditText(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    public boolean onKeyPreIme(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            // User has pressed Back key. So hide the keyboard
            InputMethodManager mgr = (InputMethodManager)         

           getContext().getSystemService(Context.INPUT_METHOD_SERVICE);
            mgr.hideSoftInputFromWindow(this.getWindowToken(), 0);
            // TODO: Hide your view as you do it in your activity
        }
        return false;
}

在您的 XML 中

<com.YOURAPP.CustomEditText
     android:id="@+id/CEditText"
     android:layout_height="wrap_content"
     android:layout_width="match_parent"/> 

在您的活动中

public class MainActivity extends Activity {
   private CustomEditText editText;

   @Override
   public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      editText = (CustomEditText) findViewById(R.id.CEditText);
   }
}

---

是的，完全可以显示和隐藏键盘并拦截对返回按钮的调用。这是一个额外的努力，因为已经提到在 API 中没有直接的方法来做到这一点。关键是在布局中覆盖 boolean dispatchKeyEventPreIme(KeyEvent)。我们所做的是创建我们的布局。我选择了 RelativeLayout，因为它是我的 Activity 的基础。

<?xml version="1.0" encoding="utf-8"?>
<com.michaelhradek.superapp.utilities.SearchLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res/com.michaelhradek.superapp"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@color/white">

在我们的 Activity 中，我们设置输入字段并调用 setActivity(...) 函数。

private void initInputField() {
    mInputField = (EditText) findViewById(R.id.searchInput);        

    InputMethodManager imm = 
        (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE); 
    imm.toggleSoftInput(InputMethodManager.SHOW_FORCED, 
            InputMethodManager.HIDE_IMPLICIT_ONLY);

    mInputField.setOnEditorActionListener(new OnEditorActionListener() {

        @Override
        public boolean onEditorAction(TextView v, int actionId,
                KeyEvent event) {
            if (actionId == EditorInfo.IME_ACTION_SEARCH) {
                performSearch();
                return true;
            }

            return false;
        }
    });

    // Let the layout know we are going to be overriding the back button
    SearchLayout.setSearchActivity(this);
}

显然，initInputField() 函数设置了输入字段。它还使输入键能够执行功能（在我的例子中是搜索）。

@Override
public void onBackPressed() {
    // It's expensive, if running turn it off.
    DataHelper.cancelSearch();
    hideKeyboard();
    super.onBackPressed();
}

因此，当在我们的布局中调用 onBackPressed() 时，我们可以做任何我们想做的事情，比如隐藏键盘：

private void hideKeyboard() {
    InputMethodManager imm = (InputMethodManager) 
        getSystemService(Context.INPUT_METHOD_SERVICE);
    imm.hideSoftInputFromWindow(mInputField.getWindowToken(), 0);
}

无论如何，这是我对 RelativeLayout 的覆盖。

package com.michaelhradek.superapp.utilities;

import android.app.Activity;
import android.content.Context;
import android.util.AttributeSet;
import android.util.Log;
import android.view.KeyEvent;
import android.widget.RelativeLayout;

/**
 * The root element in the search bar layout. This is a custom view just to 
 * override the handling of the back button.
 * 
 */
public class SearchLayout extends RelativeLayout {

    private static final String TAG = "SearchLayout";

    private static Activity mSearchActivity;;

    public SearchLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public SearchLayout(Context context) {
        super(context);
    }

    public static void setSearchActivity(Activity searchActivity) {
        mSearchActivity = searchActivity;
    }

    /**
     * Overrides the handling of the back key to move back to the 
     * previous sources or dismiss the search dialog, instead of 
     * dismissing the input method.
     */
    @Override
    public boolean dispatchKeyEventPreIme(KeyEvent event) {
        Log.d(TAG, "dispatchKeyEventPreIme(" + event + ")");
        if (mSearchActivity != null && 
                    event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
            KeyEvent.DispatcherState state = getKeyDispatcherState();
            if (state != null) {
                if (event.getAction() == KeyEvent.ACTION_DOWN
                        && event.getRepeatCount() == 0) {
                    state.startTracking(event, this);
                    return true;
                } else if (event.getAction() == KeyEvent.ACTION_UP
                        && !event.isCanceled() && state.isTracking(event)) {
                    mSearchActivity.onBackPressed();
                    return true;
                }
            }
        }

        return super.dispatchKeyEventPreIme(event);
    }
}

不幸的是，我不能接受所有的功劳。如果您检查 Android source for the quick SearchDialog box，您会看到这个想法的来源。

---

我发现，覆盖 Layout 类的 dispatchKeyEventPreIme 方法也很有效。只需将您的主要活动设置为属性并启动预定义的方法。

public class LinearLayoutGradient extends LinearLayout {
    MainActivity a;

    public void setMainActivity(MainActivity a) {
        this.a = a;
    }

    @Override
    public boolean dispatchKeyEventPreIme(KeyEvent event) {
        if (a != null) {
            InputMethodManager imm = (InputMethodManager) a
                .getSystemService(Context.INPUT_METHOD_SERVICE);

            if (imm.isActive() && event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
                a.launchMethod;
            }
        }

        return super.dispatchKeyEventPreIme(event);
    }
}

---

我通过覆盖 dispatchKeyEvent 取得了成功：

@Override
public boolean dispatchKeyEvent(KeyEvent event) {
    if (event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
        finish();
        return true;
    }
    return super.dispatchKeyEvent(event);
}

它隐藏键盘并完成活动。

---

你如何显示软键盘？

如果您使用 InputMethodManager.showSoftInput()，您可以尝试传入 ResultReceiver 并实现 onReceiveResult() 来处理 RESULT_HIDDEN

http://developer.android.com/reference/android/view/inputmethod/InputMethodManager.html

---

我有同样的问题，但通过拦截后退键来解决它。在我的情况下（HTC Desire，Android 2.2，应用程序 API 级别 4）它关闭键盘并立即完成活动。不知道为什么这也不适合你：

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK) {
        return true;
    }
    return super.onKeyDown(keyCode, event);
}

@Override
public boolean onKeyUp(int keyCode, KeyEvent event) {
    if (keyCode == KeyEvent.KEYCODE_BACK) {
        onBackPressed();
        return true;
    }
    return super.onKeyUp(keyCode, event);
}

/**
 * Called when the activity has detected the user's press of the back key
 */
private void onBackPressed() {
    Log.e(TAG, "back pressed");
    finish();
}

---

使用 onKeyPreIme(int keyCode, KeyEvent event) 方法并检查 KeyEvent.KEYCODE_BACK 事件。它非常简单，无需进行任何花哨的编码。

---

在您的 BackPressed 实现 (Block Back Button in android) 中尝试此代码：

InputMethodManager imm = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
imm.hideSoftInputFromWindow(myEditText.getWindowToken(), 0);

我建议你看看@Close/hide the Android Soft Keyboard

---

我的@mhradek 解决方案版本：

布局

class BazingaLayout @JvmOverloads constructor(context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0) :
    ConstraintLayout(context, attrs, defStyleAttr) {

var activity: Activity? = null

override fun dispatchKeyEventPreIme(event: KeyEvent): Boolean {
    activity?.let {
        if (event.keyCode == KeyEvent.KEYCODE_BACK) {
            val state = keyDispatcherState
            if (state != null) {
                if (event.action == KeyEvent.ACTION_DOWN
                    && event.repeatCount == 0) {
                    state.startTracking(event, this)
                    return true
                } else if (event.action == KeyEvent.ACTION_UP && !event.isCanceled && state.isTracking(event)) {
                    it.onBackPressed()
                    return true
                }
            }
        }
    }
    return super.dispatchKeyEventPreIme(event)
}

}

xml文件

<com... BazingaLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/grey">
 </com... BazingaLayout>

分段

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        (view as BazingaLayout).activity = activity
        super.onViewCreated(view, savedInstanceState)
}

---

这是我的 @kirill-rakhman's 解决方案的变体。

我需要知道在键盘显示时何时按下了硬件或手势后退按钮，以便我可以做出反应并显示一个在任何编辑文本视图获得焦点时之前隐藏的按钮。

首先声明你需要的回调接口

interface KeyboardEventListener {
   fun onKeyBoardDismissedIme()
}

然后使用监听器创建自定义视图以获取 pre ime 键事件

class KeyboardAwareConstraintLayout(context: Context, attrs: AttributeSet) :
    ConstraintLayout(context, attrs) {

    var listener: KeyboardEventListener? = null

    override fun dispatchKeyEventPreIme(event: KeyEvent?): Boolean {
        val imm: InputMethodManager =
            context.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
        if (imm.isActive && event?.keyCode == KeyEvent.KEYCODE_BACK) {
            listener?.onKeyBoardDismissedIme()
        }
        return super.dispatchKeyEventPreIme(event)
    }
}

使用自定义布局视图包裹您的布局

<com.package_name.KeyboardAwareLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/keyBoardAwareLayout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

{Your layout children here}    

</com.package_name.KeyboardAwareLayout>

接下来在您的活动或片段中实现回调接口并设置键盘感知布局

class MyFragment : Fragment, KeyboardEventListener {

    // TODO: Setup some viewbinding to retrieve the view reference

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        binding.keyBoardAwareLayout.listener = this
    }

    override fun onKeyBoardDismissedIme() {
        // TODO: React to keyboard hidden with back button
    }
}

---