protected void hideSoftKeyboard(EditText input) {
    InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
    imm.hideSoftInputFromWindow(input.getWindowToken(), 0);    
}

如果有人感兴趣的话，我已经为Kotlin写了一个小扩展，但没有太多测试：

fun Fragment.hideKeyboard(context: Context = App.instance) {
    val windowToken = view?.rootView?.windowToken
    windowToken?.let {
        val imm = context.getSystemService(Activity.INPUT_METHOD_SERVICE) as InputMethodManager
        imm.hideSoftInputFromWindow(windowToken, 0)
    }
}

App.instance是存储在Application中的静态“this”Application对象

更新：在某些情况下，windowToken为空。我增加了使用反射来检测键盘是否关闭的额外关闭方式

/**
 * If no window token is found, keyboard is checked using reflection to know if keyboard visibility toggle is needed
 *
 * @param useReflection - whether to use reflection in case of no window token or not
 */
fun Fragment.hideKeyboard(context: Context = MainApp.instance, useReflection: Boolean = true) {
    val windowToken = view?.rootView?.windowToken
    val imm = context.getSystemService(Context.INPUT_METHOD_SERVICE) as InputMethodManager
    windowToken?.let {
        imm.hideSoftInputFromWindow(windowToken, 0)
    } ?: run {
        if (useReflection) {
            try {
                if (getKeyboardHeight(imm) > 0) {
                    imm.toggleSoftInput(0, InputMethodManager.HIDE_NOT_ALWAYS)
                }
            } catch (exception: Exception) {
                Timber.e(exception)
            }
        }
    }
}

fun getKeyboardHeight(imm: InputMethodManager): Int = InputMethodManager::class.java.getMethod("getInputMethodWindowVisibleHeight").invoke(imm) as Int

与Android 10（API 29）一起工作

val activityView = activity?.window?.decorView?.rootView
activityView?.let {
    val imm = activity?.getSystemService(Context.INPUT_METHOD_SERVICE) as? InputMethodManager
    imm?.hideSoftInputFromWindow(it.windowToken, 0)
}

当您触摸编辑文本或其他任何地方时，此代码将帮助您隐藏键盘。您需要在您的活动中添加此代码，或者您可以在项目的父活动中编写，它也将在webview中隐藏您的键盘。

@Override
public boolean dispatchTouchEvent(MotionEvent ev) {
    View v = getCurrentFocus();

    if (v != null && (ev.getAction() == MotionEvent.ACTION_UP || ev.getAction() == MotionEvent.ACTION_MOVE) && v instanceof EditText &&
            !v.getClass().getName().startsWith("android.webkit.")) {
        int[] sourceCoordinates = new int[2];
        v.getLocationOnScreen(sourceCoordinates);
        float x = ev.getRawX() + v.getLeft() - sourceCoordinates[0];
        float y = ev.getRawY() + v.getTop() - sourceCoordinates[1];

        if (x < v.getLeft() || x > v.getRight() || y < v.getTop() || y > v.getBottom()) {
            hideKeyboard(this);
        }

    }
    return super.dispatchTouchEvent(ev);
}

private void hideKeyboard(Activity activity) {
    if (activity != null && activity.getWindow() != null) {
        activity.getWindow().getDecorView();
        InputMethodManager imm = (InputMethodManager) activity.getSystemService(Context.INPUT_METHOD_SERVICE);
        if (imm != null) {
            imm.hideSoftInputFromWindow(activity.getWindow().getDecorView().getWindowToken(), 0);
        }
    }
}

public static void hideKeyboard(View view) {
        if (view != null) {
            InputMethodManager imm = (InputMethodManager) view.getContext().getSystemService(Context.INPUT_METHOD_SERVICE);
            if (imm != null)
                imm.hideSoftInputFromWindow(view.getWindowToken(), 0);
        }
    }

 //In Activity
        View v = this.getCurrentFocus();
        if (v != null) {
            InputMethodManager im = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
            im.hideSoftInputFromWindow(view.getWindowToken(), 0);
        }


//In Fragment
        View v = getActivity().getCurrentFocus();
        if (v != null) {
            InputMethodManager im = (InputMethodManager)getActivity().getSystemService(Context.INPUT_METHOD_SERVICE);
            im.hideSoftInputFromWindow(view.getWindowToken(), 0);
        }
```

以下是使用Kotlin隐藏软键盘的最简单方法：

//hides soft keyboard anything else is tapped( screen, menu bar, buttons, etc. )
override fun dispatchTouchEvent( ev: MotionEvent? ): Boolean {
    if ( currentFocus != null ) {
        val imm = getSystemService( Context.INPUT_METHOD_SERVICE ) as InputMethodManager
        imm.hideSoftInputFromWindow( currentFocus!!.windowToken, 0 )
    }
    return super.dispatchTouchEvent( ev )
}