为了补充@Sam_D的答案，我必须这样做才能使它工作:

this.setTitle("my title!");
((TextView)v.findViewById(R.id.title)).setText(this.getTitle());
TextView title = ((TextView)v.findViewById(R.id.title));
title.setEllipsize(TextUtils.TruncateAt.MARQUEE);
title.setMarqueeRepeatLimit(1);
// in order to start strolling, it has to be focusable and focused
title.setFocusable(true);
title.setSingleLine(true);
title.setFocusableInTouchMode(true);
title.requestFocus();

这似乎有点过分-两次引用v.f entviewbyid (R.id.title)) -但这是唯一的方法，它会让我这样做。

从Android支持库v26 + Android Studio 3.0起，这个过程变得简单如轻弹!!

按照以下步骤更改工具栏标题的字体:

Read Downloadable Fonts & select any font from the list (my recommendation) or load a custom font to res > font as per Fonts in XML In res > values > styles, paste the following (use your imagination here!) <style name="TitleBarTextAppearance" parent="android:TextAppearance"> <item name="android:fontFamily">@font/your_desired_font</item> <item name="android:textSize">23sp</item> <item name="android:textStyle">bold</item> <item name="android:textColor">@android:color/white</item> </style> Insert a new line in your Toolbar properties app:titleTextAppearance="@style/TextAppearance.TabsFont" as shown below <android.support.v7.widget.Toolbar android:id="@+id/toolbar" android:layout_width="match_parent" android:layout_height="?attr/actionBarSize" android:background="?attr/colorPrimary" app:titleTextAppearance="@style/TitleBarTextAppearance" app:popupTheme="@style/AppTheme.PopupOverlay"/> Enjoy Custom Actionbar Title font styling!!

int titleId = getResources().getIdentifier("action_bar_title", "id",
            "android");
    TextView yourTextView = (TextView) findViewById(titleId);
    yourTextView.setTextColor(getResources().getColor(R.color.black));
    yourTextView.setTypeface(face);

书法库让你通过应用程序主题设置自定义字体，这也适用于操作栏。

<style name="AppTheme" parent="android:Theme.Holo.Light.DarkActionBar">
<item name="android:textViewStyle">@style/AppTheme.Widget.TextView</item>
</style>

<style name="AppTheme.Widget"/>

<style name="AppTheme.Widget.TextView" parent="android:Widget.Holo.Light.TextView">
   <item name="fontPath">fonts/Roboto-ThinItalic.ttf</item>
</style>

激活书法所需要的是将它附加到你的活动上下文:

@Override
protected void attachBaseContext(Context newBase) {
    super.attachBaseContext(new CalligraphyContextWrapper(newBase));
}

默认的自定义属性是fontPath，但是您可以通过在Application类中使用calligraphy hyconfig . builder初始化它来为路径提供您自己的自定义属性。不鼓励使用android:fontFamily。

您可以使用自定义TypefaceSpan类来实现这一点。它优于上面提到的customView方法，因为它在使用其他操作栏元素(如展开操作视图)时不会中断。

这样一个类的使用应该是这样的:

SpannableString s = new SpannableString("My Title");
s.setSpan(new TypefaceSpan(this, "MyTypeface.otf"), 0, s.length(),
        Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);

// Update the action bar title with the TypefaceSpan instance
ActionBar actionBar = getActionBar();
actionBar.setTitle(s);

自定义TypefaceSpan类传递给您的Activity上下文和assets/fonts目录中的字体名称。它加载文件并在内存中缓存一个新的字体实例。TypefaceSpan的完整实现非常简单:

/**
 * Style a {@link Spannable} with a custom {@link Typeface}.
 * 
 * @author Tristan Waddington
 */
public class TypefaceSpan extends MetricAffectingSpan {
      /** An <code>LruCache</code> for previously loaded typefaces. */
    private static LruCache<String, Typeface> sTypefaceCache =
            new LruCache<String, Typeface>(12);

    private Typeface mTypeface;

    /**
     * Load the {@link Typeface} and apply to a {@link Spannable}.
     */
    public TypefaceSpan(Context context, String typefaceName) {
        mTypeface = sTypefaceCache.get(typefaceName);

        if (mTypeface == null) {
            mTypeface = Typeface.createFromAsset(context.getApplicationContext()
                    .getAssets(), String.format("fonts/%s", typefaceName));

            // Cache the loaded Typeface
            sTypefaceCache.put(typefaceName, mTypeface);
        }
    }

    @Override
    public void updateMeasureState(TextPaint p) {
        p.setTypeface(mTypeface);

        // Note: This flag is required for proper typeface rendering
        p.setFlags(p.getFlags() | Paint.SUBPIXEL_TEXT_FLAG);
    }

    @Override
    public void updateDrawState(TextPaint tp) {
        tp.setTypeface(mTypeface);

        // Note: This flag is required for proper typeface rendering
        tp.setFlags(tp.getFlags() | Paint.SUBPIXEL_TEXT_FLAG);
    }
}

简单地复制上面的类到你的项目中，并在你的活动的onCreate方法中实现它，如上所示。

没有自定义的文本视图是必需的!

首先，在你的java代码中禁用工具栏中的标题: getSupportActionBar () .setDisplayShowTitleEnabled(假);

然后，只需在工具栏内添加一个TextView:

<android.support.v7.widget.Toolbar
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="?attr/colorPrimary"
    app:popupTheme="@style/AppTheme.PopupOverlay">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/app_name"
        android:textSize="18sp"
        android:fontFamily="@font/roboto" />

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