试试这个

public void findAndSetFont(){
        getActionBar().setTitle("SOME TEST TEXT");
        scanForTextViewWithText(this,"SOME TEST TEXT",new SearchTextViewInterface(){

            @Override
            public void found(TextView title) {

            } 
        });
    }

public static void scanForTextViewWithText(Activity activity,String searchText, SearchTextViewInterface searchTextViewInterface){
    if(activity == null|| searchText == null || searchTextViewInterface == null)
        return;
    View view = activity.findViewById(android.R.id.content).getRootView();
    searchForTextViewWithTitle(view, searchText, searchTextViewInterface);
}

private static void searchForTextViewWithTitle(View view, String searchText, SearchTextViewInterface searchTextViewInterface)
{
    if (view instanceof ViewGroup)
    {
        ViewGroup g = (ViewGroup) view;
        int count = g.getChildCount();
        for (int i = 0; i < count; i++)
            searchForTextViewWithTitle(g.getChildAt(i), searchText, searchTextViewInterface);
    }
    else if (view instanceof TextView)
    {
        TextView textView = (TextView) view;
        if(textView.getText().toString().equals(searchText))
            if(searchTextViewInterface!=null)
                searchTextViewInterface.found(textView);
    }
}
public interface SearchTextViewInterface {
    void found(TextView title);
}

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

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));
    }
}

    ActionBar actionBar = getSupportActionBar();
    TextView tv = new TextView(getApplicationContext());
    Typeface typeface = ResourcesCompat.getFont(this, R.font.monotype_corsiva);
    RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(
            RelativeLayout.LayoutParams.MATCH_PARENT, // Width of TextView
            RelativeLayout.LayoutParams.WRAP_CONTENT); // Height of TextView
    tv.setLayoutParams(lp);
    tv.setText("Your Text"); // ActionBar title text
    tv.setTextSize(25);
    tv.setTextColor(Color.WHITE);
    tv.setTypeface(typeface, typeface.ITALIC);
    actionBar.setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
    actionBar.setCustomView(tv);

这是一个丑陋的黑客，但你可以这样做(因为action_bar_title是隐藏的):

    try {
        Integer titleId = (Integer) Class.forName("com.android.internal.R$id")
                .getField("action_bar_title").get(null);
        TextView title = (TextView) getWindow().findViewById(titleId);
        // check for null and manipulate the title as see fit
    } catch (Exception e) {
        Log.e(TAG, "Failed to obtain action bar title reference");
    }

这段代码适用于后姜饼设备，但也可以很容易地扩展到动作栏Sherlock

附注:基于@pjv评论，有一个更好的方法找到操作栏标题id

final int titleId = 
    Resources.getSystem().getIdentifier("action_bar_title", "id", "android");

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);
    }

}