如何在 Android 中判断软件键盘的可见性

NEW ANSWER added Jan 25th 2012

在写了下面的答案后，有人告诉我ViewTreeObserver和friends的存在，这些API从版本1开始就潜伏在SDK中.

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

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);
}

容易的

Note: 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.

ORIGINAL ANSWER

是的，这是可能的，但这远比它应该的难.

如果我需要关心键盘何时出现和消失(这是很常见的)，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空间明显小于窗口的总面积，则可能会显示一个软键盘.

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);       
    }

    }

然后在你的活动课上...

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
    }

    ...
}