如果你想在整个活动中设置所有textview的字体，你可以使用这样的东西:

public static void setTypefaceToAll(Activity activity)
{
    View view = activity.findViewById(android.R.id.content).getRootView();
    setTypefaceToAll(view);
}

public static void setTypefaceToAll(View view)
{
    if (view instanceof ViewGroup)
    {
        ViewGroup g = (ViewGroup) view;
        int count = g.getChildCount();
        for (int i = 0; i < count; i++)
            setTypefaceToAll(g.getChildAt(i));
    }
    else if (view instanceof TextView)
    {
        TextView tv = (TextView) view;
        setTypeface(tv);
    }
}

public static void setTypeface(TextView tv)
{
    TypefaceCache.setFont(tv, TypefaceCache.FONT_KOODAK);
}

TypefaceCache:

import java.util.TreeMap;

import android.graphics.Typeface;
import android.widget.TextView;

public class TypefaceCache {

    //Font names from asset:
    public static final String FONT_ROBOTO_REGULAR = "fonts/Roboto-Regular.ttf";
    public static final String FONT_KOODAK = "fonts/Koodak.ttf";

    private static TreeMap<String, Typeface> fontCache = new TreeMap<String, Typeface>();

    public static Typeface getFont(String fontName) {
        Typeface tf = fontCache.get(fontName);
        if(tf == null) {
            try {
                tf = Typeface.createFromAsset(MyApplication.getAppContext().getAssets(), fontName);
            }
            catch (Exception e) {
                return null;
            }
            fontCache.put(fontName, tf);
        }
        return tf;
    }

    public static void setFont(TextView tv, String fontName)
    {
        tv.setTypeface(getFont(fontName));
    }
}

我们需要使用反射来实现这一点

final int titleId = activity.getResources().getIdentifier("action_bar_title", "id", "android");

    final TextView title;
    if (activity.findViewById(titleId) != null) {
        title = (TextView) activity.findViewById(titleId);
        title.setTextColor(Color.BLACK);
        title.setTextColor(configs().getColor(ColorKey.GENERAL_TEXT));
        title.setTypeface(configs().getTypeface());
    } else {
        try {
            Field f = bar.getClass().getDeclaredField("mTitleTextView");
            f.setAccessible(true);
            title = (TextView) f.get(bar);
            title.setTextColor(Color.BLACK);
            title.setTypeface(configs().getTypeface());
        } catch (NoSuchFieldException e) {
        } catch (IllegalAccessException e) {
        }
    }

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!!

我只是在onCreate()函数中做了以下工作:

TypefaceSpan typefaceSpan = new TypefaceSpan("font_to_be_used");
SpannableString str = new SpannableString("toolbar_text");
str.setSpan(typefaceSpan,0, str.length(), Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
getSupportActionBar().setTitle(str);

我正在使用支持库，如果你不使用它们，我猜你应该切换到getActionBar()而不是getSupportActionBar()。

在Android Studio 3中，您可以按照以下说明添加自定义字体https://developer.android.com/guide/topics/ui/look-and-feel/fonts-in-xml.html，然后在“font_to_be_used”中使用您新添加的字体

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。

使用新的工具栏在支持库设计你自己的动作栏或使用下面的代码

膨胀的Textview不是一个好的选择，尝试可扩展的字符串生成器

Typeface font2 = Typeface.createFromAsset(getAssets(), "fonts/<your font in assets folder>");   
SpannableStringBuilder SS = new SpannableStringBuilder("MY Actionbar Tittle");
SS.setSpan (new CustomTypefaceSpan("", font2), 0, SS.length(),Spanned.SPAN_EXCLUSIVE_INCLUSIVE);
actionBar.setTitle(ss);

复制以下类

public class CustomTypefaceSpan extends TypefaceSpan{

    private final Typeface newType;

    public CustomTypefaceSpan(String family, Typeface type) {
        super(family);
        newType = type;
    }

    @Override
    public void updateDrawState(TextPaint ds) {
        applyCustomTypeFace(ds, newType);
    }

    @Override
    public void updateMeasureState(TextPaint paint) {
        applyCustomTypeFace(paint, newType);
    }

    private static void applyCustomTypeFace(Paint paint, Typeface tf) {
        int oldStyle;
        Typeface old = paint.getTypeface();
        if (old == null) {
            oldStyle = 0;
        } else {
            oldStyle = old.getStyle();
        }

        int fake = oldStyle & ~tf.getStyle();
        if ((fake & Typeface.BOLD) != 0) {
            paint.setFakeBoldText(true);
        }

        if ((fake & Typeface.ITALIC) != 0) {
            paint.setTextSkewX(-0.25f);
        }

        paint.setTypeface(tf);
    }

}