你可以用下面的like

 <android.support.v7.widget.Toolbar
    android:id="@+id/top_actionbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:theme="@style/AppThemeToolbar">

    <TextView
        android:id="@+id/pageTitle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="center"
        />
</android.support.v7.widget.Toolbar>

一个非常快速和简单的方法来设置自定义字体是使用自定义titleTextAppearance与fontFamily:

添加到styles.xml:

<style name="ToolbarTitle" parent="TextAppearance.Widget.AppCompat.Toolbar.Title">
    <item name="android:textSize">16sp</item>
    <item name="android:textColor">#FF202230</item>
    <item name="android:fontFamily">@font/varela_round_regular</item>
</style>

在res文件夹中创建一个字体文件夹(例如:varela_round_regular.ttf)

阅读官方指南，了解更多https://developer.android.com/guide/topics/ui/look-and-feel/fonts-in-xml.html

您可以在xml文件中插入这段代码

 <androidx.appcompat.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@color/colorPrimaryDark"
    android:elevation="4dp"
    android:theme="@style/ThemeOverlay.AppCompat.ActionBar">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Toolbar Title"
        android:textColor="#000000"
        android:textSize="20dp"
        android:id="@+id/toolbar_title" />

</androidx.appcompat.widget.Toolbar>

要在工具栏中使用自定义标题，您可以添加一个自定义标题，如:

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/toolbar"
    android:layout_width="match_parent"
    android:layout_height="?attr/actionBarSize"
    android:background="?attr/colorPrimary"
    android:elevation="5dp"
    app:contentInsetLeft="0dp"
    app:contentInsetStart="0dp"
    app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
    app:theme="@style/ThemeOverlay.AppCompat.Dark">


        <LinearLayout
            android:id="@+id/lnrTitle"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="center_horizontal"
            android:orientation="vertical">

            <TextView
                android:id="@+id/txvHeader"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center_horizontal|center"
                android:gravity="center"
                android:ellipsize="end"
                android:maxLines="1"
                android:text="Header"
                android:textColor="@color/white"
                android:textSize="18sp" />


        </LinearLayout>


</android.support.v7.widget.Toolbar>

Java代码:

Toolbar toolbar = findViewById(R.id.toolbar);

setSupportActionBar(toolbar);

if (getSupportActionBar() == null)
    return;

getSupportActionBar().setTitle("Title");

getSupportActionBar().setDisplayHomeAsUpEnabled(true);

我找到了另一种方法来添加自定义工具栏，而不需要任何额外的Java/Kotlin代码。

First: create a XML with your custom toolbar layout with AppBarLayout as the parent: <?xml version="1.0" encoding="utf-8"?> <android.support.design.widget.AppBarLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="wrap_content" android:theme="@style/AppTheme.AppBarOverlay"> <android.support.v7.widget.Toolbar android:id="@+id/toolbar" android:layout_width="match_parent" android:layout_height="?attr/actionBarSize" android:background="?attr/colorPrimary" app:popupTheme="@style/AppTheme.PopupOverlay"> <ImageView android:layout_width="80dp" android:layout_height="wrap_content" android:layout_gravity="right" android:layout_marginEnd="@dimen/magin_default" android:src="@drawable/logo" /> </android.support.v7.widget.Toolbar> Second: Include the toolbar in your layout: <?xml version="1.0" encoding="utf-8"?> <android.support.constraint.ConstraintLayout 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" android:background="@color/blue" tools:context=".app.MainAcitivity" tools:layout_editor_absoluteY="81dp"> <include layout="@layout/toolbar_inicio" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> <!-- Put your layout here --> </android.support.constraint.ConstraintLayout>

Try

@Override
    public void onBackPressed() {
          if(getTitle().equals(getResources().getString(R.string.app_name))) {
            super.onBackPressed();}
          else {
//set visiblity
           }
}