如何检查 Android 中软键盘的可见性? [英] How to check visibility of software keyboard in Android?

问题描述

我需要做一件非常简单的事情 - 找出是否显示了软键盘.这在 Android 中可行吗?

I need to do a very simple thing - find out if the software keyboard is shown. Is this possible in Android?

推荐答案

NEW ANSWER 于 2012 年 1 月 25 日添加

自从写下下面的答案后，有人告诉我ViewTreeObserver 和朋友们，从版本 1 开始就潜伏在 SDK 中的 API.

Since writing the below answer, someone clued me in to the existence of ViewTreeObserver and friends, APIs which have been lurking in the SDK since version 1.

不需要自定义布局类型，一个更简单的解决方案是为您的活动的根视图提供一个已知 ID，例如 @+id/activityRoot，将 GlobalLayoutListener 连接到 ViewTreeObserver 中，然后从那里计算您的活动的视图根和窗口大小之间的大小差异:

Rather than requiring a custom Layout type, a much simpler solution is to give your activity's root view a known ID, say @+id/activityRoot, hook a GlobalLayoutListener into the ViewTreeObserver, and from there calculate the size diff between your activity's view root and the window size:

final View activityRootView = findViewById(R.id.activityRoot);
activityRootView.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
    @Override
    public void onGlobalLayout() {
        int heightDiff = activityRootView.getRootView().getHeight() - activityRootView.getHeight();
        if (heightDiff > dpToPx(this, 200)) { // if more than 200 dp, it's probably a keyboard...
            // ... do something here
        }
     }
});

使用实用程序，例如:

public static float dpToPx(Context context, float valueInDp) {
    DisplayMetrics metrics = context.getResources().getDisplayMetrics();
    return TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, valueInDp, metrics);
}

简单！

注意:您的应用程序必须在 Android Manifest android:windowSoftInputMode="adjustResize" 中设置此标志，否则上述解决方案将不起作用.

Note: Your application must set this flag in Android Manifest android:windowSoftInputMode="adjustResize" otherwise above solution will not work.

原答案

是的，这是可能的，但它比应有的要困难得多.

Yes it's possible, but it's far harder than it ought to be.

如果我需要关心键盘何时出现和消失(这很常见)，那么我要做的就是将我的顶级布局类自定义为一个覆盖 onMeasure() 的类.基本逻辑是，如果布局发现自己填充的面积明显小于窗口的总面积，则可能显示的是软键盘.

If I need to care about when the keyboard appears and disappears (which is quite often) then what I do is customize my top-level layout class into one which overrides onMeasure(). The basic logic is that if the layout finds itself filling significantly less than the total area of the window, then a soft keyboard is probably showing.

import android.app.Activity;
import android.content.Context;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.widget.LinearLayout;

/*
 * LinearLayoutThatDetectsSoftKeyboard - a variant of LinearLayout that can detect when 
 * the soft keyboard is shown and hidden (something Android can't tell you, weirdly). 
 */

public class LinearLayoutThatDetectsSoftKeyboard extends LinearLayout {

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

    public interface Listener {
        public void onSoftKeyboardShown(boolean isShowing);
    }
    private Listener listener;
    public void setListener(Listener listener) {
        this.listener = listener;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int height = MeasureSpec.getSize(heightMeasureSpec);
        Activity activity = (Activity)getContext();
        Rect rect = new Rect();
        activity.getWindow().getDecorView().getWindowVisibleDisplayFrame(rect);
        int statusBarHeight = rect.top;
        int screenHeight = activity.getWindowManager().getDefaultDisplay().getHeight();
        int diff = (screenHeight - statusBarHeight) - height;
        if (listener != null) {
            listener.onSoftKeyboardShown(diff>128); // assume all soft keyboards are at least 128 pixels high
        }
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);       
    }

    }

然后在您的 Activity 类中...

Then in your Activity class...

public class MyActivity extends Activity implements LinearLayoutThatDetectsSoftKeyboard.Listener {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ...
        LinearLayoutThatDetectsSoftKeyboard mainLayout = (LinearLayoutThatDetectsSoftKeyboard)findViewById(R.id.main);
        mainLayout.setListener(this);
        ...
    }


    @Override
    public void onSoftKeyboardShown(boolean isShowing) {
        // do whatever you need to do here
    }

    ...
}

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