我有一个带有多个输入字段的活动。当活动开始时,软键盘会显示。当按下返回按钮时,软键盘关闭,要关闭活动,我需要再按一次后退按钮。
因此问题是:是否可以拦截返回按钮以关闭软键盘并在按下返回按钮时完成活动,而不创建自定义 InputMethodService
?
P.S. 我知道如何在其他情况下拦截返回按钮:onKeyDown()
或 onBackPressed()
,但在这种情况下无效:只有第二次按下返回按钮才被拦截。
我有一个带有多个输入字段的活动。当活动开始时,软键盘会显示。当按下返回按钮时,软键盘关闭,要关闭活动,我需要再按一次后退按钮。
因此问题是:是否可以拦截返回按钮以关闭软键盘并在按下返回按钮时完成活动,而不创建自定义 InputMethodService
?
P.S. 我知道如何在其他情况下拦截返回按钮:onKeyDown()
或 onBackPressed()
,但在这种情况下无效:只有第二次按下返回按钮才被拦截。
onKeyDown()和onBackPressed()在这种情况下无法正常工作。您需要使用onKeyPreIme。
最初,您需要创建扩展EditText的自定义EditText。然后,您必须实现控制KeyEvent.KEYCODE_BACK的onKeyPreIme方法。之后,一次返回足以解决您的问题。这个解决方案对我来说完美地运行。
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;
}
在你的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,并拦截对后退按钮的调用。虽然没有直接的API方法来实现此功能,但仍需付出一些额外的努力。关键是在布局中覆盖 boolean dispatchKeyEventPreIme(KeyEvent)
方法。我们要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()
函数设置了输入框,并启用回车键执行功能(在我的情况下是搜索)。
@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,我们可以执行任何操作,例如隐藏键盘:
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);
}
}
不幸的是我不能完全拥有这个功劳。如果您检查Android的快速搜索对话框的源代码,您将看到这个想法是从哪里来的。
getContext()
强制转换为 Activity
,就可以简化代码。当然,前提是布局的上下文确实是所涉及的活动(即当前活动)。但我不知道这是否可能。 - mxcl我发现,覆盖Layout类的dispatchKeyEventPreIme方法也很有效。只需将您的主Activity设置为属性并启动预定义的方法即可。
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);
}
}
<?xml version="1.0" encoding="utf-8"?> <view class="package.LinearLayoutGradient"...
- Kirill Rakhman我通过重写 dispatchKeyEvent 方法成功了:
@Override
public boolean dispatchKeyEvent(KeyEvent event) {
if (event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
finish();
return true;
}
return super.dispatchKeyEvent(event);
}
http://developer.android.com/reference/android/view/inputmethod/InputMethodManager.html
showSoftInput()
在我的手机和模拟器上无法显示键盘,所以我使用toggleSoftInput()
。 - Sergey Glotov我曾经遇到过同样的问题,但通过拦截后退键按下来解决了。在我的情况下(HTC Desire, Android 2.2, Application API Level 4),它会关闭键盘并立即完成活动。不知道为什么这对你也不起作用:
@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();
}
onKeyPreIme(int keyCode, KeyEvent event)
方法并检查 KeyEvent.KEYCODE_BACK
事件。 这很简单,不需要进行任何花式编程。我对@mhradek解决方案的版本:
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>
片段
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
(view as BazingaLayout).activity = activity
super.onViewCreated(view, savedInstanceState)
}
在你的 BackPressed 实现中尝试这段代码(阻止 Android 返回按钮):
InputMethodManager imm = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
imm.hideSoftInputFromWindow(myEditText.getWindowToken(), 0);
我建议你看一下关闭/隐藏Android软键盘
onBackPressed()
无法正常工作。只有在第二次按下后,程序才会进入 onBackPressed()
方法。 - Sergey Glotov这是我对@kirill-rakhman的解决方案的变体。
当键盘显示时,我需要知道硬件或手势返回按钮被按下的时间,以便我可以做出反应并显示之前隐藏的按钮,当任何编辑文本视图获得焦点时。
interface KeyboardEventListener {
fun onKeyBoardDismissedIme()
}
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)
}
}
<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>
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
}
}