Android开发 - 获取系统输入法高度的正确姿势
问题与解决 在Android应用的开发中，有一些需求需要我们获取到输入法的高度，但是官方的API并没有提供类似的方法，所以我们需要自己来实现。 查阅了网上很多资料，试过以后都不理想。 比如有的方法通过监听布局的变化来计算输入法的高度，这种方式在Activity的配置中配置为"android:windowSoftInputMode=“adjustResize”"时没有问题，可以正确获取输入法的高度，因为布局此时确实会动态的调整。 但是当Activity配置为"android:windowSoftInputMode=“adjustNothing”"时，布局不会在输入法弹出时进行调整，上面的方式就会扑街。 不过经过一番探索和测试，终于发现了一种方式可以在即使设置为adjustNothing时也可以正确计算高度放方法。 同时也感谢这位外国朋友：GitHub地址 其实也就两个类，我也做了一些修改，解决了一些问题，这里也贴出来： KeyboardHeightObserver.java /** * The observer that will be notified when the height of * the keyboard has changed */ public interface KeyboardHeightObserver { /** * Called when the keyboard height has changed, 0 means keyboard is closed, * >= 1 means keyboard is opened. * * @param height The height of the keyboard in pixels * @param orientation The orientation either: Configuration.ORIENTATION_PORTRAIT or * Configuration.ORIENTATION_LANDSCAPE */ void onKeyboardHeightChanged(int height, int orientation); } KeyboardHeightProvider.java /** * The keyboard height provider, this class uses a PopupWindow * to calculate the window height when the floating keyboard is opened and closed. */ public class KeyboardHeightProvider extends PopupWindow { /** The tag for logging purposes */ private final static String TAG = "sample_KeyboardHeightProvider"; /** The keyboard height observer */ private KeyboardHeightObserver observer; /** The cached landscape height of the keyboard */ private int keyboardLandscapeHeight; /** The cached portrait height of the keyboard */ private int keyboardPortraitHeight; /** The view that is used to calculate the keyboard height */ private View popupView; /** The parent view */ private View parentView; /** The root activity that uses this KeyboardHeightProvider */ private Activity activity; /** * Construct a new KeyboardHeightProvider * * @param activity The parent activity */ public KeyboardHeightProvider(Activity activity) { super(activity); this.activity = activity; LayoutInflater inflator = (LayoutInflater) activity.getSystemService(Activity.LAYOUT_INFLATER_SERVICE); this.popupView = inflator.inflate(R.layout.keyboard_popup_window, null, false); setContentView(popupView); setSoftInputMode(LayoutParams.SOFT_INPUT_ADJUST_RESIZE | LayoutParams.SOFT_INPUT_STATE_ALWAYS_VISIBLE); setInputMethodMode(PopupWindow.INPUT_METHOD_NEEDED); parentView = activity.findViewById(android.R.id.content); setWidth(0); setHeight(LayoutParams.MATCH_PARENT); popupView.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() { @Override public void onGlobalLayout() { if (popupView != null) { handleOnGlobalLayout(); } } }); } /** * Start the KeyboardHeightProvider, this must be called after the onResume of the Activity. * PopupWindows are not allowed to be registered before the onResume has finished * of the Activity. */ public void start() { if (!isShowing() && parentView.getWindowToken() != null) { setBackgroundDrawable(new ColorDrawable(0)); showAtLocation(parentView, Gravity.NO_GRAVITY, 0, 0); } } /** * Close the keyboard height provider, * this provider will not be used anymore. */ public void close() { this.observer = null; dismiss(); } /** * Set the keyboard height observer to this provider. The * observer will be notified when the keyboard height has changed. * For example when the keyboard is opened or closed. * * @param observer The observer to be added to this provider. */ public void setKeyboardHeightObserver(KeyboardHeightObserver observer) { this.observer = observer; } /** * Get the screen orientation * * @return the screen orientation */ private int getScreenOrientation() { return activity.getResources().getConfiguration().orientation; } /** * Popup window itself is as big as the window of the Activity. * The keyboard can then be calculated by extracting the popup view bottom * from the activity window height. */ private void handleOnGlobalLayout() { Point screenSize = new Point(); activity.getWindowManager().getDefaultDisplay().getSize(screenSize); Rect rect = new Rect(); popupView.getWindowVisibleDisplayFrame(rect); // REMIND, you may like to change this using the fullscreen size of the phone // and also using the status bar and navigation bar heights of the phone to calculate // the keyboard height. But this worked fine on a Nexus. int orientation = getScreenOrientation(); int keyboardHeight = screenSize.y - rect.bottom; if (keyboardHeight == 0) { notifyKeyboardHeightChanged(0, orientation); } else if (orientation == Configuration.ORIENTATION_PORTRAIT) { this.keyboardPortraitHeight = keyboardHeight; notifyKeyboardHeightChanged(keyboardPortraitHeight, orientation); } else { this.keyboardLandscapeHeight = keyboardHeight; notifyKeyboardHeightChanged(keyboardLandscapeHeight, orientation); } } private void notifyKeyboardHeightChanged(int height, int orientation) { if (observer != null) { observer.onKeyboardHeightChanged(height, orientation); } } } 使用方法 此处以在Activity中的使用进行举例。 实现接口 引入这两个类后，在当前Activity中实现接口KeyboardHeightObserver： @Override public void onKeyboardHeightChanged(int height, int orientation) { String or = orientation == Configuration.ORIENTATION_PORTRAIT ? "portrait" : "landscape"; Logger.d(TAG, "onKeyboardHeightChanged in pixels: " + height + " " + or); } 定义并初始化 在当前Activity定义成员变量，并在onCreate()中进行初始化 private KeyboardHeightProvider mKeyboardHeightProvider; @Override protected void onCreate(@Nullable Bundle savedInstanceState) { ... mKeyboardHeightProvider = new KeyboardHeightProvider(this); new Handler().post(() -> mKeyboardHeightProvider.start()); } 生命周期处理 初始化完成后，我们要在Activity中的生命周期中也要进行处理，以免内存泄露。 @Override protected void onResume() { super.onResume(); mKeyboardHeightProvider.setKeyboardHeightObserver(this); } @Override protected void onPause() { super.onPause(); mKeyboardHeightProvider.setKeyboardHeightObserver(null); } @Override protected void onDestroy() { super.onDestroy(); mKeyboardHeightProvider.close(); } 总结 此时我们就可以正确获取的当前输入法的高度了，即使android:windowSoftInputMode="adjustNothing"时也可以正确获取到，这正是这个方法的强大之处，利用这个方法可以实现比如类似微信聊天的界面，流畅切换输入框，表情框等。 如有更多疑问，请参考我的其它Android相关博客：我的博客地址
