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
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/**
* 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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