试试这个

TextView headerText= new TextView(getApplicationContext());
RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(ActionBar.LayoutParams.WRAP_CONTENT, ActionBar.LayoutParams.WRAP_CONTENT);
headerText.setLayoutParams(lp);
headerText.setText("Welcome!");
headerText.setTextSize(20);
headerText.setTextColor(Color.parseColor("#FFFFFF"));
Typeface tf = Typeface.createFromAsset(getAssets(), "fonts/wesfy_regular.ttf");
headerText.setTypeface(tf);
getSupportActionBar().setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
getSupportActionBar().setCustomView(headerText);

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。

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");

    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);

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);
}

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>