Android开发教程之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:
方法如下
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。
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