有一个隐藏的方法可以帮助这个，inputmethodmanager。getinputmethodwindowvisibleheight。但我不知道为什么要藏起来。

import android.content.Context
import android.os.Handler
import android.view.inputmethod.InputMethodManager

class SoftKeyboardStateWatcher(private val ctx: Context) {
  companion object {
    private const val DELAY = 10L
  }

  private val handler = Handler()
  private var isSoftKeyboardOpened: Boolean = false

  private val height: Int
    get() {
      val imm = ctx.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
      val method = imm.javaClass.getMethod("getInputMethodWindowVisibleHeight")
      method.isAccessible = true
      return method.invoke(imm) as Int
    }

  private val task: Runnable by lazy {
    Runnable {
      start()
      if (!isSoftKeyboardOpened && height > 0) {
        isSoftKeyboardOpened = true
        notifyOnSoftKeyboardOpened(height)
      } else if (isSoftKeyboardOpened && height == 0) {
        isSoftKeyboardOpened = false
        notifyOnSoftKeyboardClosed()
      }
    }
  }

  var listener: SoftKeyboardStateListener? = null

  interface SoftKeyboardStateListener {
    fun onSoftKeyboardOpened(keyboardHeightInPx: Int)
    fun onSoftKeyboardClosed()
  }

  fun start() {
    handler.postDelayed(task, DELAY)
  }

  fun stop() {
    handler.postDelayed({
      if (!isSoftKeyboardOpened) handler.removeCallbacks(task)
    }, DELAY * 10)
  }

  private fun notifyOnSoftKeyboardOpened(keyboardHeightInPx: Int) {
    listener?.onSoftKeyboardOpened(keyboardHeightInPx)
  }

  private fun notifyOnSoftKeyboardClosed() {
    listener?.onSoftKeyboardClosed()
  }
}

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

在使用上述大多数建议添加固定数字的解决方案时，我刚刚遇到了一个错误。

S4的dpi很高，导致导航栏的高度为100px，因此我的应用程序认为键盘一直是打开的。

所以，随着所有新的高分辨率手机的发布，我认为使用硬编码值从长远来看不是一个好主意。

在各种屏幕和设备上进行测试后，我发现一个更好的方法是使用百分比。 获取decorView和你的应用内容之间的差异，然后检查这个差异的百分比。 从我得到的统计数据来看，大多数导航栏(无论大小、分辨率等)将占据屏幕的3%到5%。如果键盘是打开的，它会占据屏幕的47%到55%。

作为结论，我的解决方案是检查是否差异超过10%，然后我假设它的键盘打开。

有一个隐藏的方法可以帮助这个，inputmethodmanager。getinputmethodwindowvisibleheight。但我不知道为什么要藏起来。

import android.content.Context
import android.os.Handler
import android.view.inputmethod.InputMethodManager

class SoftKeyboardStateWatcher(private val ctx: Context) {
  companion object {
    private const val DELAY = 10L
  }

  private val handler = Handler()
  private var isSoftKeyboardOpened: Boolean = false

  private val height: Int
    get() {
      val imm = ctx.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
      val method = imm.javaClass.getMethod("getInputMethodWindowVisibleHeight")
      method.isAccessible = true
      return method.invoke(imm) as Int
    }

  private val task: Runnable by lazy {
    Runnable {
      start()
      if (!isSoftKeyboardOpened && height > 0) {
        isSoftKeyboardOpened = true
        notifyOnSoftKeyboardOpened(height)
      } else if (isSoftKeyboardOpened && height == 0) {
        isSoftKeyboardOpened = false
        notifyOnSoftKeyboardClosed()
      }
    }
  }

  var listener: SoftKeyboardStateListener? = null

  interface SoftKeyboardStateListener {
    fun onSoftKeyboardOpened(keyboardHeightInPx: Int)
    fun onSoftKeyboardClosed()
  }

  fun start() {
    handler.postDelayed(task, DELAY)
  }

  fun stop() {
    handler.postDelayed({
      if (!isSoftKeyboardOpened) handler.removeCallbacks(task)
    }, DELAY * 10)
  }

  private fun notifyOnSoftKeyboardOpened(keyboardHeightInPx: Int) {
    listener?.onSoftKeyboardOpened(keyboardHeightInPx)
  }

  private fun notifyOnSoftKeyboardClosed() {
    listener?.onSoftKeyboardClosed()
  }
}

这个想法是，如果你需要隐藏你的键盘，同时检查软输入状态，使用以下解决方案:

public boolean hideSoftInput() {
    InputMethodManager imm = (InputMethodManager) getSystemService(Activity.INPUT_METHOD_SERVICE);
    return imm.hideSoftInputFromWindow(mViewPager.getWindowToken(), 0);
}

如果在隐藏之前显示键盘，则此方法返回true。

你可以通过使用活动的decorView来观察软键盘的隐藏。

public final class SoftKeyboardUtil {
    public static final String TAG = "SoftKeyboardUtil";
    public static void observeSoftKeyBoard(Activity activity , final OnSoftKeyBoardHideListener listener){
        final View decorView = activity.getWindow().getDecorView();
        decorView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
            @Override
            public void onGlobalLayout() {
                Rect rect = new Rect();
                decorView.getWindowVisibleDisplayFrame(rect);
                int displayHight = rect.bottom - rect.top;
                int hight = decorView.getHeight();
                boolean hide = (double)displayHight / hight > 0.8 ;
                if(Log.isLoggable(TAG, Log.DEBUG)){
                    Log.d(TAG ,"DecorView display hight = "+displayHight);
                    Log.d(TAG ,"DecorView hight = "+ hight);
                    Log.d(TAG, "softkeyboard visible = " + !hide);
                }

                listener.onSoftKeyBoardVisible(!hide);

            }
        });
    }



    public interface OnSoftKeyBoardHideListener{
        void onSoftKeyBoardVisible(boolean visible);
    }
}