定义以下类:

public class CenteredToolbar extends Toolbar {

    private TextView centeredTitleTextView;

    public CenteredToolbar(Context context) {
        super(context);
    }

    public CenteredToolbar(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public CenteredToolbar(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    public void setTitle(@StringRes int resId) {
        String s = getResources().getString(resId);
        setTitle(s);
    }

    @Override
    public void setTitle(CharSequence title) {
        getCenteredTitleTextView().setText(title);
    }

    @Override
    public CharSequence getTitle() {
        return getCenteredTitleTextView().getText().toString();
    }

    public void setTypeface(Typeface font) {
        getCenteredTitleTextView().setTypeface(font);
    }

    private TextView getCenteredTitleTextView() {
        if (centeredTitleTextView == null) {
            centeredTitleTextView = new TextView(getContext());
            centeredTitleTextView.setTypeface(...);
            centeredTitleTextView.setSingleLine();
            centeredTitleTextView.setEllipsize(TextUtils.TruncateAt.END);
            centeredTitleTextView.setGravity(Gravity.CENTER);
            centeredTitleTextView.setTextAppearance(getContext(), R.style.TextAppearance_AppCompat_Widget_ActionBar_Title);

            Toolbar.LayoutParams lp = new Toolbar.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
            lp.gravity = Gravity.CENTER;
            centeredTitleTextView.setLayoutParams(lp);

            addView(centeredTitleTextView);
        }
        return centeredTitleTextView;
    }
}

.．.然后使用它来代替常规工具栏，就像这样:

<RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/colorAccent">

        <your.packagename.here.CenteredToolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="?attr/colorPrimary"
            android:minHeight="?attr/actionBarSize"
            android:theme="?attr/actionBarTheme"
            app:title="@string/reset_password_page_title"/>

        <!-- Other views -->

</RelativeLayout>

在Activity中你仍然需要这两行代码(和标准工具栏一样):

Toolbar toolbar = (Toolbar) findViewByid(R.id.toolbar); // note that your activity doesn't need to know that it is actually a custom Toolbar
setSupportActionBar(binding.toolbar);

就是这样!您不需要隐藏标准的左对齐标题，不需要重复相同的XML代码，等等，只需使用CenteredToolbar，如果它是默认的工具栏。您还可以通过编程方式设置您的自定义字体，因为您现在可以直接访问TextView。希望这能有所帮助。

现在使用材质设计3，我们可以在中间对齐标题，而不需要做额外的工作，也不需要在工具栏中添加文本视图

在构建中添加了以下依赖项。gradle文件

implementation 'com.google.android.material:material:1.6.1'

为了使标题在中心对齐，我们需要正确地使用下面的内容

 app:titleCentered="true"

为了在中心对齐字幕，我们需要使用下面的属性

app:subtitleCentered="true"

示例代码

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

  <com.google.android.material.appbar.AppBarLayout
      android:layout_width="match_parent"
      android:layout_height="wrap_content">

    <com.google.android.material.appbar.MaterialToolbar
        android:id="@+id/topAppBar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        app:title="AskNilesh"
        app:subtitle="Nilesh"
        app:subtitleCentered="true"
        app:menu="@menu/top_app_bar"
        app:titleCentered="true"
        app:navigationIcon="@drawable/ic_android_black_24dp" />

  </com.google.android.material.appbar.AppBarLayout>

  <androidx.core.widget.NestedScrollView
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      app:layout_behavior="@string/appbar_scrolling_view_behavior">


  </androidx.core.widget.NestedScrollView>

</androidx.coordinatorlayout.widget.CoordinatorLayout>

输出

设置android:gravity="center"对我来说很有效

没有造型，什么都没有。工具栏基本上是一个ViewGroup，你需要做的就是在其中设置元素的重力。

        <android.support.v7.widget.Toolbar
            android:id="@+id/htab_toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:layout_gravity="top"
            android:background="@color/partial_transparent"
            android:gravity="center"
            app:layout_collapseMode="pin"
            app:layout_scrollFlags="scroll|enterAlways"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light" />

这里是标题文本依赖的方法，从工具栏找到TextView实例。

  public static TextView getToolbarTitleView(ActionBarActivity activity, Toolbar toolbar){
    ActionBar actionBar = activity.getSupportActionBar();
    CharSequence actionbarTitle = null;
    if(actionBar != null)
        actionbarTitle = actionBar.getTitle();
    actionbarTitle = TextUtils.isEmpty(actionbarTitle) ? toolbar.getTitle() : actionbarTitle;
    if(TextUtils.isEmpty(actionbarTitle)) return null;
    // can't find if title not set
    for(int i= 0; i < toolbar.getChildCount(); i++){
        View v = toolbar.getChildAt(i);
        if(v != null && v instanceof TextView){
            TextView t = (TextView) v;
            CharSequence title = t.getText();
            if(!TextUtils.isEmpty(title) && actionbarTitle.equals(title) && t.getId() == View.NO_ID){
                //Toolbar does not assign id to views with layout params SYSTEM, hence getId() == View.NO_ID
                //in same manner subtitle TextView can be obtained.
                return t;
            }
        }
    }
    return null;
}

private void makeTitleCenter(String title, Toolbar toolbar) {
    if (title != null && !TextUtils.isEmpty(title.trim())) {
        final String tag = " ";
        if (getSupportActionBar() != null) {
            getSupportActionBar().setTitle(tag);
        }
        TextView titleTv = null;
        View leftBtn = null;
        for (int i = 0; i < toolbar.getChildCount(); i++) {
            View view = toolbar.getChildAt(i);
            CharSequence text = null;
            if (view instanceof TextView && (text = ((TextView) view).getText()) != null && text.equals(tag)) {
                titleTv = (TextView) view;
            } else if (view instanceof ImageButton) {
                leftBtn = view;
            }
        }
        if (titleTv != null) {
            final TextView fTitleTv = titleTv;
            final View fLeftBtn = leftBtn;
            fTitleTv.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
                @Override
                public void onGlobalLayout() {
                    fTitleTv.getViewTreeObserver().removeOnGlobalLayoutListener(this);
                    int leftWidgetWidth = fLeftBtn != null ? fLeftBtn.getWidth() : 0;
                    fTitleTv.setPadding(DimenUtil.getResources().getDisplayMetrics().widthPixels / 2 - leftWidgetWidth - fTitleTv.getWidth() / 2, 0, 0, 0);
                    fTitleTv.requestLayout();
                }
            });
        }
    }
}

这是我用一个导航图标和一个文本视图所做的 现在您可以进行扩展，以便在任何需要的地方应用它。但你必须把它应用到每一项活动中

(toolbar[0] as AppCompatTextView).let {
            it.viewTreeObserver.addOnDrawListener {
                it.layoutParams = it.layoutParams.apply {
                    width = Toolbar.LayoutParams.MATCH_PARENT
                    (this as ViewGroup.MarginLayoutParams).apply {
                        marginEnd = toolbar[1].width
                    }
                }
                it.textAlignment = View.TEXT_ALIGNMENT_CENTER
            }

        }