关于Android中软键盘显示隐藏的监听判断总结

前言

很多时候我们需要知道软键盘是否打开和关闭，从而处理一些需求。之前在做shou app的时候，由于交互比较复杂，需要知道软键盘是开启或者关闭，决定是否让视频全屏，还是让聊天室全屏，或者是正常显示(上面是视频，下面是聊天室)

ViewTreeObserver.OnGlobalLayoutListener

OnGlobalLayoutListener 是ViewTreeObserver的内部类，当一个视图树的布局发生改变时，可以被ViewTreeObserver监听到，这是一个注册监听视图树的观察者(observer)，在视图树的全局事件改变时得到通知。ViewTreeObserver不能直接实例化，而是通过getViewTreeObserver()获得。 以上是说明，摘抄自http://www.cnblogs.com/superle/p/4567400.html这篇文章，也就是说，通过这个api，我们可以知道view的布局状态变化

如何监听软键盘

KeyboardChangeListener github上有这样的一个轮子，测试了下，的确有效，思路是，对android.R.id.content所对应的view设置监听，监听它的高度变化，计算比较，来确定软件盘是否弹起或者收拢了。这种模式需要设置activity android:windowSoftInputMode="adjustResize"

full screen模式下如何监听软件盘

在full screen 状态上，发现，以上的方案完全不起作用了。在https://pspdfkit.com/blog/2016/keyboard-handling-on-android/ 上找到了解决办法。 大致上说的是full screen模式下，adjustResize不会生效了，window不会resize的。  getWindowVisibleDisplayFrame(Rect)这个api可以获取到view所在的区域，通过它比较每次区域的变化，可以实现监听软键盘是否可见 完整代码为:

public class KeyBoardChangeListener implements ViewTreeObserver.OnGlobalLayoutListener {
    private static final String TAG = "KeyBoardChangeListener";
    // Threshold for minimal keyboard height.
    final int MIN_KEYBOARD_HEIGHT_PX = 150;
    private final Rect windowVisibleDisplayFrame = new Rect();
    // Top-level window decor view.
    private View decorView;
    private int lastVisibleDecorViewHeight;
    private KeyBoardListener keyBoardListener;

    KeyBoardChangeListener(Activity activity) {
        if (activity == null) {
            Log.e(TAG, "activity is null");
            return;
        }
        decorView = activity.getWindow().getDecorView();
        decorView.getViewTreeObserver().addOnGlobalLayoutListener(this);
    }

    public void setKeyBoardListener(KeyBoardListener keyBoardListener) {
        this.keyBoardListener = keyBoardListener;
    }

    @Override
    public void onGlobalLayout() {
        // Retrieve visible rectangle inside window.
        decorView.getWindowVisibleDisplayFrame(windowVisibleDisplayFrame);
        final int visibleDecorViewHeight = windowVisibleDisplayFrame.height();
        // Decide whether keyboard is visible from changing decor view height.
        if (lastVisibleDecorViewHeight != 0) {
            if (lastVisibleDecorViewHeight > visibleDecorViewHeight + MIN_KEYBOARD_HEIGHT_PX) {
                // Calculate current keyboard height (this includes also navigation bar height when in fullscreen mode).
                int currentKeyboardHeight = decorView.getHeight() - windowVisibleDisplayFrame.bottom;
                // Notify listener about keyboard being shown.
                if (keyBoardListener != null) {
                    keyBoardListener.onKeyboardChange(true, currentKeyboardHeight);
                }
            } else if (lastVisibleDecorViewHeight + MIN_KEYBOARD_HEIGHT_PX < visibleDecorViewHeight) {
                // Notify listener about keyboard being hidden.
                if (keyBoardListener != null) {
                    keyBoardListener.onKeyboardChange(false, 0);
                }
            }
        }
        // Save current decor view height for the next call.
        lastVisibleDecorViewHeight = visibleDecorViewHeight;
    }

    public interface KeyBoardListener {
        /**
         * call back
         *
         * @param isShow         true is show else hidden
         * @param keyboardHeight keyboard height
         */
        void onKeyboardChange(boolean isShow, int keyboardHeight);
    }
}

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相关参考

https://pspdfkit.com/blog/2016/keyboard-handling-on-android/ KeyboardChangeListener https://gist.github.com/xingstarx/7a535fdda432e7678b53c628099c96ab