本文工具转载自：https://blog.csdn.net/passerby_b/article/details/82686662
使用方法：
activity 的onCreate() 中设置
SoftHideKeyBoardUtil.assistActivity(this);
工具类：
public class SoftHideKeyBoardUtil {
public static void assistActivity(Activity activity) {
new SoftHideKeyBoardUtil(activity);
}
private View mChildOfContent;
private int usableHeightPrevious;
private FrameLayout.LayoutParams frameLayoutParams;
//为适应华为小米等手机键盘上方出现黑条或不适配
private int contentHeight;//获取setContentView本来view的高度
private boolean isfirst = true;//只用获取一次
private int statusBarHeight;//状态栏高度
private SoftHideKeyBoardUtil(Activity activity) {
//1､找到Activity的最外层布局控件，它其实是一个DecorView,它所用的控件就是FrameLayout
FrameLayout content = (FrameLayout) activity.findViewById(android.R.id.content);
//2､获取到setContentView放进去的View
mChildOfContent = content.getChildAt(0);
//3､给Activity的xml布局设置View树监听，当布局有变化，如键盘弹出或收起时，都会回调此监听
mChildOfContent.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
//4､软键盘弹起会使GlobalLayout发生变化
public void onGlobalLayout() {
if (isfirst) {
contentHeight = mChildOfContent.getHeight();//兼容华为等机型
isfirst = false;
}
//5､当前布局发生变化时，对Activity的xml布局进行重绘
possiblyResizeChildOfContent();
}
});
//6､获取到Activity的xml布局的放置参数
frameLayoutParams = (FrameLayout.LayoutParams) mChildOfContent.getLayoutParams();
}
// 获取界面可用高度，如果软键盘弹起后，Activity的xml布局可用高度需要减去键盘高度
private void possiblyResizeChildOfContent() {
//1､获取当前界面可用高度，键盘弹起后，当前界面可用布局会减少键盘的高度
int usableHeightNow = computeUsableHeight();
//2､如果当前可用高度和原始值不一样
if (usableHeightNow != usableHeightPrevious) {
//3､获取Activity中xml中布局在当前界面显示的高度
int usableHeightSansKeyboard = mChildOfContent.getRootView().getHeight();
//4､Activity中xml布局的高度-当前可用高度
int heightDifference = usableHeightSansKeyboard - usableHeightNow;
//5､高度差大于屏幕1/4时，说明键盘弹出
if (heightDifference > (usableHeightSansKeyboard / 4)) {
// 6､键盘弹出了，Activity的xml布局高度应当减去键盘高度
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
frameLayoutParams.height = usableHeightSansKeyboard - heightDifference + statusBarHeight;
} else {
frameLayoutParams.height = usableHeightSansKeyboard - heightDifference;
}
} else {
frameLayoutParams.height = contentHeight;
}
//7､ 重绘Activity的xml布局
mChildOfContent.requestLayout();
usableHeightPrevious = usableHeightNow;
}
}
private int computeUsableHeight() {
Rect r = new Rect();
mChildOfContent.getWindowVisibleDisplayFrame(r);
// 全屏模式下：直接返回r.bottom，r.top其实是状态栏的高度
return (r.bottom - r.top);
}
}