对于Xamarin.Android：

public void HideKeyboard()
{
    var imm = activity.GetSystemService(Context.InputMethodService).JavaCast<InputMethodManager>();
    var view = activity.CurrentFocus ?? new View(activity);
    imm.HideSoftInputFromWindow(view.WindowToken, HideSoftInputFlags.None);
}

感谢上帝，它在11年后得到了官方支持

首先将依赖实现“androidx.core:core-ktx:1.7.0”添加到appgradle

然后从ViewCompat或WindowCompat类获取InsetsController。

最后使用InsetsController的hide（）和show（）函数

已编辑添加对Dialog的支持。在BottomSheetDialog中提供@隆德夫。使用更安全的方式获取活动，而不是直接从上下文中强制转换。

import android.app.Activity
import android.app.Dialog
import android.content.Context
import android.content.ContextWrapper
import android.view.View
import androidx.core.view.ViewCompat
import androidx.core.view.WindowCompat
import androidx.core.view.WindowInsetsCompat
import androidx.fragment.app.Fragment

fun View.showKeyboard() = ViewCompat.getWindowInsetsController(this)?.show(WindowInsetsCompat.Type.ime())
fun View.hideKeyboard() = ViewCompat.getWindowInsetsController(this)?.hide(WindowInsetsCompat.Type.ime())

fun Dialog.showKeyboard() = window?.decorView?.showKeyboard()
fun Dialog.hideKeyboard() = window?.decorView?.hideKeyboard()

fun Context.showKeyboard() = getActivity()?.showKeyboard()
fun Context.hideKeyboard() = getActivity()?.hideKeyboard()

fun Fragment.showKeyboard() = activity?.showKeyboard()
fun Fragment.hideKeyboard() = activity?.hideKeyboard()

fun Activity.showKeyboard() = WindowCompat.getInsetsController(window, window.decorView)?.show(WindowInsetsCompat.Type.ime())
fun Activity.hideKeyboard() = WindowCompat.getInsetsController(window, window.decorView)?.hide(WindowInsetsCompat.Type.ime())

fun Context.getActivity(): Activity? {
    return when (this) {
        is Activity -> this
        is ContextWrapper -> this.baseContext.getActivity()
        else -> null
    }
}

下面是旧的anwser

下面是github上的简单项目

import android.app.Activity
import android.app.Dialog
import android.content.Context
import android.content.ContextWrapper
import android.view.View
import androidx.core.view.ViewCompat
import androidx.core.view.WindowCompat
import androidx.core.view.WindowInsetsCompat
import androidx.fragment.app.Fragment

fun View.showKeyboard() = ViewCompat.getWindowInsetsController(this)?.show(WindowInsetsCompat.Type.ime())
fun View.hideKeyboard() = ViewCompat.getWindowInsetsController(this)?.hide(WindowInsetsCompat.Type.ime())

fun Dialog.showKeyboard() = window?.decorView?.showKeyboard()
fun Dialog.hideKeyboard() = window?.decorView?.hideKeyboard()

fun Context.showKeyboard() = getActivity()?.showKeyboard()
fun Context.hideKeyboard() = getActivity()?.hideKeyboard()

fun Fragment.showKeyboard() = activity?.showKeyboard()
fun Fragment.hideKeyboard() = activity?.hideKeyboard()

fun Activity.showKeyboard() = WindowCompat.getInsetsController(window, window.decorView)?.show(WindowInsetsCompat.Type.ime())
fun Activity.hideKeyboard() = WindowCompat.getInsetsController(window, window.decorView)?.hide(WindowInsetsCompat.Type.ime())

fun Context.getActivity(): Activity? {
    return when (this) {
        is Activity -> this
        is ContextWrapper -> this.baseContext.getActivity()
        else -> null
    }
}

Meier的解决方案也适用于我。在我的例子中，我的应用程序的顶层是一个选项卡宿主，我想在切换选项卡时隐藏关键字-我从选项卡宿主视图获取窗口令牌。

tabHost.setOnTabChangedListener(new OnTabChangeListener() {
    public void onTabChanged(String tabId) {
        InputMethodManager imm = (InputMethodManager) getSystemService(Context.INPUT_METHOD_SERVICE);
        imm.hideSoftInputFromWindow(tabHost.getApplicationWindowToken(), 0);
    }
}

以上答案适用于不同的场景，但如果您想将键盘隐藏在视图中，并努力获得正确的上下文，请尝试以下操作：

setOnClickListener(new OnClickListener() {
    @Override
    public void onClick(View v) {
        hideSoftKeyBoardOnTabClicked(v);
    }
}

private void hideSoftKeyBoardOnTabClicked(View v) {
    if (v != null && context != null) {
        InputMethodManager imm = (InputMethodManager) context.getSystemService(Context.INPUT_METHOD_SERVICE);
        imm.hideSoftInputFromWindow(v.getApplicationWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);
    }
}

并从构造函数获取上下文：）

public View/RelativeLayout/so and so (Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    this.context = context;
    init();
}

在Kotlin

fun hideKeyboard(activity: BaseActivity) {
        val view = activity.currentFocus?: View(activity)
        val imm = activity.getSystemService(Activity.INPUT_METHOD_SERVICE) as InputMethodManager
        imm.hideSoftInputFromWindow(view.windowToken, 0)
    }

public static void hideSoftKeyboard(Activity activity) {
    InputMethodManager inputMethodManager = (InputMethodManager) activity
            .getSystemService(Activity.INPUT_METHOD_SERVICE);
    inputMethodManager.hideSoftInputFromWindow(activity.getCurrentFocus()
            .getWindowToken(), 0);
}