2012年1月25日新增答案

写了下面的答案后，有人告诉我ViewTreeObserver和其他api的存在，这些api从版本1开始就潜伏在SDK中。

而不是需要一个自定义的布局类型，一个更简单的解决方案是给你的活动的根视图一个已知的ID，比如@+ ID /activityRoot，钩子一个GlobalLayoutListener到ViewTreeObserver，并从那里计算你的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
        }
     }
});

使用一个实用程序，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: 你的应用程序必须在Android Manifest中设置这个标志Android:windowSoftInputMode=" adjuststresize "否则上述解决方案将无法工作。

原来的答案

是的，这是可能的，但它比应该的要难得多。

如果我需要关心键盘何时出现和消失(这是相当经常的)，那么我所做的是自定义我的顶级布局类为一个覆盖onMeasure()。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，那么可能显示了软键盘。

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
    }

    ...
}

InputMethodManager有关于软键盘的信息。你从一个活动中获得它:

((InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE))

你可以摆弄一下，看看它能告诉你什么。你可以用它来显示或隐藏软输入…

检查元素的高度是不可靠的，因为一些键盘，如WifiKeyboard的高度为零。

相反，您可以使用showSoftInput()和hideSoftInput()的回调结果来检查键盘的状态。完整的细节和示例代码在

https://rogerkeays.com/how-to-check-if-the-software-keyboard-is-shown-in-android

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

一些改进，以避免在高密度设备上错误地检测软键盘的可见性:

Threshold of height difference should be defined as 128 dp, not 128 pixels. Refer to Google design doc about Metrics and Grid, 48 dp is comfortable size for touch object and 32 dp is minimum for buttons. Generic soft keyboard should include 4 rows of key buttons, so minimum keyboard height should be: 32 dp * 4 = 128 dp, that means threshold size should transfer to pixels by multiply device density. For xxxhdpi devices (density 4), the soft keyboard height threshold should be 128 * 4 = 512 pixels. Height difference between root view and its visible area: root view height - status bar height - visible frame height = root view bottom - visible frame bottom, since status bar height equal to the top of root view visible frame. private final String TAG = "TextEditor"; private TextView mTextEditor; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_editor); mTextEditor = (TextView) findViewById(R.id.text_editor); mTextEditor.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() { @Override public void onGlobalLayout() { isKeyboardShown(mTextEditor.getRootView()); } }); } private boolean isKeyboardShown(View rootView) { /* 128dp = 32dp * 4, minimum button height 32dp and generic 4 rows soft keyboard */ final int SOFT_KEYBOARD_HEIGHT_DP_THRESHOLD = 128; Rect r = new Rect(); rootView.getWindowVisibleDisplayFrame(r); DisplayMetrics dm = rootView.getResources().getDisplayMetrics(); /* heightDiff = rootView height - status bar height (r.top) - visible frame height (r.bottom - r.top) */ int heightDiff = rootView.getBottom() - r.bottom; /* Threshold size: dp to pixels, multiply with display density */ boolean isKeyboardShown = heightDiff > SOFT_KEYBOARD_HEIGHT_DP_THRESHOLD * dm.density; Log.d(TAG, "isKeyboardShown ? " + isKeyboardShown + ", heightDiff:" + heightDiff + ", density:" + dm.density + "root view height:" + rootView.getHeight() + ", rect:" + r); return isKeyboardShown; }

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) {

    }
});