在了解了不同分辨率的一些问题后，我决定使用相对大小。正如我所注意到的，可见状态和隐藏状态之间的差异约为30%。所以我决定用0.3代替128 PX。

我添加了这个类监听器来通知任何变化。

这是我的版本

import android.app.*;
import android.graphics.*;
import android.view.*;

public class SoftKeyboardState {
  public static final int HIDDEN = 0, VISIBLE = 1;
  private OnKeyboardStateChangedListener listener;
  private View decorView;

  public SoftKeyboardState(Activity activity) {
    this.decorView = activity.findViewById(android.R.id.content);
    initKeyboardListener();
  }

  private void initKeyboardListener() {
    decorView.getViewTreeObserver().addOnGlobalLayoutListener(
      new ViewTreeObserver.OnGlobalLayoutListener(){
        private final Rect windowVisibleDisplayFrame = new Rect();
        private int lastVisibleDecorViewHeight;

        @Override
        public void onGlobalLayout() {
          decorView.getWindowVisibleDisplayFrame(windowVisibleDisplayFrame);
          final int visibleDecorViewHeight = windowVisibleDisplayFrame.height();

          if (lastVisibleDecorViewHeight != 0) {
            if ((lastVisibleDecorViewHeight > visibleDecorViewHeight) && (lastVisibleDecorViewHeight / visibleDecorViewHeight >= 0.3f)) {
              // visible
              if (listener != null)listener.onKeyboardStateChanged(VISIBLE);
            } else if ((lastVisibleDecorViewHeight < visibleDecorViewHeight) && (visibleDecorViewHeight / lastVisibleDecorViewHeight >= 0.3f)) {
              // hidden
              if (listener != null)listener.onKeyboardStateChanged(HIDDEN);
            }
          }
          lastVisibleDecorViewHeight = visibleDecorViewHeight;
        }
      });
  }

  public void setOnKeyboardStateChangedListener(OnKeyboardStateChangedListener listener) {
    this.listener = listener;
  }

  public interface OnKeyboardStateChangedListener {
    public void onKeyboardStateChanged(int state);
  }
}

抱歉回答晚了，但我已经创建了一个小的帮助类来处理打开/关闭事件，通知侦听器和其他有用的东西，可能有人会发现它有帮助:

import android.graphics.Rect;
import android.view.View;
import android.view.ViewTreeObserver;

import java.util.LinkedList;
import java.util.List;

public class SoftKeyboardStateWatcher implements ViewTreeObserver.OnGlobalLayoutListener {

    public interface SoftKeyboardStateListener {
        void onSoftKeyboardOpened(int keyboardHeightInPx);
        void onSoftKeyboardClosed();
    }

    private final List<SoftKeyboardStateListener> listeners = new LinkedList<SoftKeyboardStateListener>();
    private final View activityRootView;
    private int        lastSoftKeyboardHeightInPx;
    private boolean    isSoftKeyboardOpened;

    public SoftKeyboardStateWatcher(View activityRootView) {
        this(activityRootView, false);
    }

    public SoftKeyboardStateWatcher(View activityRootView, boolean isSoftKeyboardOpened) {
        this.activityRootView     = activityRootView;
        this.isSoftKeyboardOpened = isSoftKeyboardOpened;
        activityRootView.getViewTreeObserver().addOnGlobalLayoutListener(this);
    }

    @Override
    public void onGlobalLayout() {
        final Rect r = new Rect();
        //r will be populated with the coordinates of your view that area still visible.
        activityRootView.getWindowVisibleDisplayFrame(r);

        final int heightDiff = activityRootView.getRootView().getHeight() - (r.bottom - r.top);
        if (!isSoftKeyboardOpened && heightDiff > 100) { // if more than 100 pixels, its probably a keyboard...
            isSoftKeyboardOpened = true;
            notifyOnSoftKeyboardOpened(heightDiff);
        } else if (isSoftKeyboardOpened && heightDiff < 100) {
            isSoftKeyboardOpened = false;
            notifyOnSoftKeyboardClosed();
        }
    }

    public void setIsSoftKeyboardOpened(boolean isSoftKeyboardOpened) {
        this.isSoftKeyboardOpened = isSoftKeyboardOpened;
    }

    public boolean isSoftKeyboardOpened() {
        return isSoftKeyboardOpened;
    }

    /**
     * Default value is zero {@code 0}.
     *
     * @return last saved keyboard height in px
     */
    public int getLastSoftKeyboardHeightInPx() {
        return lastSoftKeyboardHeightInPx;
    }

    public void addSoftKeyboardStateListener(SoftKeyboardStateListener listener) {
        listeners.add(listener);
    }

    public void removeSoftKeyboardStateListener(SoftKeyboardStateListener listener) {
        listeners.remove(listener);
    }

    private void notifyOnSoftKeyboardOpened(int keyboardHeightInPx) {
        this.lastSoftKeyboardHeightInPx = keyboardHeightInPx;

        for (SoftKeyboardStateListener listener : listeners) {
            if (listener != null) {
                listener.onSoftKeyboardOpened(keyboardHeightInPx);
            }
        }
    }

    private void notifyOnSoftKeyboardClosed() {
        for (SoftKeyboardStateListener listener : listeners) {
            if (listener != null) {
                listener.onSoftKeyboardClosed();
            }
        }
    }
}

使用的例子:

final SoftKeyboardStateWatcher softKeyboardStateWatcher 
    = new SoftKeyboardStateWatcher(findViewById(R.id.activity_main_layout);

// Add listener
softKeyboardStateWatcher.addSoftKeyboardStateListener(...);
// then just handle callbacks

我的答案基本上与Kachi的答案相同，但我将它包装到一个很好的helper类中，以清理它在整个应用程序中的使用方式。

import android.app.Activity;
import android.app.Fragment;
import android.graphics.Rect;
import android.view.View;
import android.view.ViewTreeObserver.OnGlobalLayoutListener;

/**
 * Detects Keyboard Status changes and fires events only once for each change
 */
public class KeyboardStatusDetector {
    KeyboardVisibilityListener visibilityListener;

    boolean keyboardVisible = false;

    public void registerFragment(Fragment f) {
        registerView(f.getView());
    }

    public void registerActivity(Activity a) {
        registerView(a.getWindow().getDecorView().findViewById(android.R.id.content));
    }

    public KeyboardStatusDetector registerView(final View v) {
        v.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {
                Rect r = new Rect();
                v.getWindowVisibleDisplayFrame(r);

                int heightDiff = v.getRootView().getHeight() - (r.bottom - r.top);
                if (heightDiff > 100) { // if more than 100 pixels, its probably a keyboard...
                    /** Check this variable to debounce layout events */
                    if(!keyboardVisible) {
                        keyboardVisible = true;
                        if(visibilityListener != null) visibilityListener.onVisibilityChanged(true);
                    }
                } else {
                    if(keyboardVisible) {
                        keyboardVisible = false;
                        if(visibilityListener != null) visibilityListener.onVisibilityChanged(false);
                    }
                }
            }
        });

        return this;
    }

    public KeyboardStatusDetector setVisibilityListener(KeyboardVisibilityListener listener) {
        visibilityListener = listener;
        return this;
    }

    public static interface KeyboardVisibilityListener {
        public void onVisibilityChanged(boolean keyboardVisible);
    }
}

你可以使用它来检测整个应用程序中的键盘变化，如下所示:

    new KeyboardStatusDetector()
            .registerFragment(fragment)  //register to a fragment 
            .registerActivity(activity)  //or register to an activity
            .registerView(view)          //or register to a view
            .setVisibilityListener(new KeyboardVisibilityListener() {
                @Override
                public void onVisibilityChanged(boolean keyboardVisible) {
                    if(keyboardVisible) {
                       //Do stuff for keyboard visible
                    }else {
                       //Do stuff for keyboard hidden
                    }
                }
            });

注意:只使用一个“寄存器”调用。它们都是一样的，只是为了方便

Reuben Scratton和Kachi提供的解决方案似乎依赖于设备的像素密度，如果你有一个高密度的设备，即使按下键盘，高度差也可能超过100。围绕这一点的工作将是看到初始高度差(键盘向下)，然后与当前的差异进行比较。

boolean isOpened = false;
int firstHeightDiff = -1;

public void setListenerToRootView(){
    final View activityRootView = getActivity().getWindow().getDecorView().findViewById(android.R.id.content);
    Rect r = new Rect();
    activityRootView.getWindowVisibleDisplayFrame(r);
    firstHeightDiff = activityRootView.getRootView().getHeight() - (r.bottom - r.top);
    activityRootView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            if (isAdded()) {
                Rect r = new Rect();
                activityRootView.getWindowVisibleDisplayFrame(r);
                int heightDiff = activityRootView.getRootView().getHeight() - (r.bottom - r.top);
                isOpened = heightDiff>firstHeightDiff+100;
                if (isAdded())
                    if(isOpened) {
                        //TODO stuff for when it is up
                    } else {
                        //TODO stuf for when it is down
                    }
            }
        }
    });
}

除了正确的答案，我必须在onCreateView的末尾添加这个，当使用一个片段内的webview。

getActivity().getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_PAN);

可能是因为我在一个片段中运行Webview，或者可能是API 30上的一个新行为，我的问题是，即使显示键盘，片段的高度也从未改变。

所以对于Fragment，整个代码应该是

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = super.onCreateView(inflater, container, savedInstanceState);
    //mWebView.postUrl("https://www.google.com/");
    final View activityRootView = view;
    layoutListener = new ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            Rect r = new Rect();
            //r will be populated with the coordinates of your view that area still visible.
            activityRootView.getWindowVisibleDisplayFrame(r);
            // This variable was created only for Debug purposes and 
            // to see the height change when clicking on a field inside mWebView
            int screenHeight = activityRootView.getRootView().getHeight();
            Log.d("onGlobalLayout", "rect: " + r.toString());
            Log.d("onGlobalLayout", "screenHeight: " + screenHeight);

            //The difference on the heights from bottom to top and on the root height
            int heightDiff = screenHeight - (r.bottom - r.top);
            Log.d("onGlobalLayout", "heightDiff: " + heightDiff);

            //I suggest to put 250 on resources to have better order
            float dpx = dpToPx(getActivity(), 250);

            if (previousHeightDiff != heightDiff) {
                if (heightDiff > dpx) {
                    isSoftKeyboardPresent = true;
                } else {
                    isSoftKeyboardPresent = false;
                }
                previousHeightDiff = heightDiff;
            }
        }
    };
    activityRootView.getViewTreeObserver().addOnGlobalLayoutListener(layoutListener);
    getActivity().getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_PAN);
    return view;
}

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

这段代码工作得很好

根视图使用这个类:

public class KeyboardConstraintLayout extends ConstraintLayout {

private KeyboardListener keyboardListener;
private EditText targetEditText;
private int minKeyboardHeight;
private boolean isShow;

public KeyboardConstraintLayout(Context context) {
    super(context);
    minKeyboardHeight = getResources().getDimensionPixelSize(R.dimen.keyboard_min_height);
}

public KeyboardConstraintLayout(Context context, AttributeSet attrs) {
    super(context, attrs);
    minKeyboardHeight = getResources().getDimensionPixelSize(R.dimen.keyboard_min_height);
}

public KeyboardConstraintLayout(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    minKeyboardHeight = getResources().getDimensionPixelSize(R.dimen.keyboard_min_height);
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    if (!isInEditMode()) {
        Activity activity = (Activity) getContext();
        @SuppressLint("DrawAllocation")
        Rect rect = new Rect();
        getWindowVisibleDisplayFrame(rect);

        int statusBarHeight = rect.top;
        int keyboardHeight = activity.getWindowManager().getDefaultDisplay().getHeight() - (rect.bottom - rect.top) - statusBarHeight;

        if (keyboardListener != null && targetEditText != null && targetEditText.isFocused()) {
            if (keyboardHeight > minKeyboardHeight) {
                if (!isShow) {
                    isShow = true;
                    keyboardListener.onKeyboardVisibility(true);
                }
            }else {
                if (isShow) {
                    isShow = false;
                    keyboardListener.onKeyboardVisibility(false);
                }
            }
        }
    }
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
}

public boolean isShowKeyboard() {
    return isShow;
}

public void setKeyboardListener(EditText targetEditText, KeyboardListener keyboardListener) {
    this.targetEditText = targetEditText;
    this.keyboardListener = keyboardListener;
}

public interface KeyboardListener {
    void onKeyboardVisibility (boolean isVisible);
}

}

在activity或fragment中设置键盘监听器:

    rootLayout.setKeyboardListener(targetEditText, new KeyboardConstraintLayout.KeyboardListener() {
    @Override
    public void onKeyboardVisibility(boolean isVisible) {

    }
});