private void makeTitleCenter(String title, Toolbar toolbar) {
    if (title != null && !TextUtils.isEmpty(title.trim())) {
        final String tag = " ";
        if (getSupportActionBar() != null) {
            getSupportActionBar().setTitle(tag);
        }
        TextView titleTv = null;
        View leftBtn = null;
        for (int i = 0; i < toolbar.getChildCount(); i++) {
            View view = toolbar.getChildAt(i);
            CharSequence text = null;
            if (view instanceof TextView && (text = ((TextView) view).getText()) != null && text.equals(tag)) {
                titleTv = (TextView) view;
            } else if (view instanceof ImageButton) {
                leftBtn = view;
            }
        }
        if (titleTv != null) {
            final TextView fTitleTv = titleTv;
            final View fLeftBtn = leftBtn;
            fTitleTv.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
                @Override
                public void onGlobalLayout() {
                    fTitleTv.getViewTreeObserver().removeOnGlobalLayoutListener(this);
                    int leftWidgetWidth = fLeftBtn != null ? fLeftBtn.getWidth() : 0;
                    fTitleTv.setPadding(DimenUtil.getResources().getDisplayMetrics().widthPixels / 2 - leftWidgetWidth - fTitleTv.getWidth() / 2, 0, 0, 0);
                    fTitleTv.requestLayout();
                }
            });
        }
    }
}

    public class TestActivity extends AppCompatActivity {
    private Toolbar toolbar;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        super.setContentView(R.layout.activity_test);

        toolbar = (Toolbar) findViewById(R.id.tool_bar); // Attaching the layout to the toolbar object
        setSupportActionBar(toolbar);

        customizeToolbar(toolbar);
    }

    public void customizeToolbar(Toolbar toolbar){
        // Save current title and subtitle
        final CharSequence originalTitle = toolbar.getTitle();
        final CharSequence originalSubtitle = toolbar.getSubtitle();

        // Temporarily modify title and subtitle to help detecting each
        toolbar.setTitle("title");
        toolbar.setSubtitle("subtitle");

        for(int i = 0; i < toolbar.getChildCount(); i++){
            View view = toolbar.getChildAt(i);

            if(view instanceof TextView){
                TextView textView = (TextView) view;


                if(textView.getText().equals("title")){
                    // Customize title's TextView
                    Toolbar.LayoutParams params = new Toolbar.LayoutParams(Toolbar.LayoutParams.WRAP_CONTENT, Toolbar.LayoutParams.MATCH_PARENT);
                    params.gravity = Gravity.CENTER_HORIZONTAL;
                    textView.setLayoutParams(params);

                    // Apply custom font using the Calligraphy library
                    Typeface typeface = TypefaceUtils.load(getAssets(), "fonts/myfont-1.otf");
                    textView.setTypeface(typeface);

                } else if(textView.getText().equals("subtitle")){
                    // Customize subtitle's TextView
                    Toolbar.LayoutParams params = new Toolbar.LayoutParams(Toolbar.LayoutParams.WRAP_CONTENT, Toolbar.LayoutParams.MATCH_PARENT);
                    params.gravity = Gravity.CENTER_HORIZONTAL;
                    textView.setLayoutParams(params);

                    // Apply custom font using the Calligraphy library
                    Typeface typeface = TypefaceUtils.load(getAssets(), "fonts/myfont-2.otf");
                    textView.setTypeface(typeface);
                }
            }
        }

        // Restore title and subtitle
        toolbar.setTitle(originalTitle);
        toolbar.setSubtitle(originalSubtitle);
    }
}

现在使用材质设计3，我们可以在中间对齐标题，而不需要做额外的工作，也不需要在工具栏中添加文本视图

在构建中添加了以下依赖项。gradle文件

implementation 'com.google.android.material:material:1.6.1'

为了使标题在中心对齐，我们需要正确地使用下面的内容

 app:titleCentered="true"

为了在中心对齐字幕，我们需要使用下面的属性

app:subtitleCentered="true"

示例代码

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout
    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">

  <com.google.android.material.appbar.AppBarLayout
      android:layout_width="match_parent"
      android:layout_height="wrap_content">

    <com.google.android.material.appbar.MaterialToolbar
        android:id="@+id/topAppBar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        app:title="AskNilesh"
        app:subtitle="Nilesh"
        app:subtitleCentered="true"
        app:menu="@menu/top_app_bar"
        app:titleCentered="true"
        app:navigationIcon="@drawable/ic_android_black_24dp" />

  </com.google.android.material.appbar.AppBarLayout>

  <androidx.core.widget.NestedScrollView
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      app:layout_behavior="@string/appbar_scrolling_view_behavior">


  </androidx.core.widget.NestedScrollView>

</androidx.coordinatorlayout.widget.CoordinatorLayout>

输出

你只需要在你的工具栏布局中添加以下一行:

app:contentInsetStart="0dp"

我不知道appcompat库中是否有任何变化，但这是相当微不足道的，不需要反射。

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

// loop through all toolbar children right after setting support 
// action bar because the text view has no id assigned

// also make sure that the activity has some title here
// because calling setText() with an empty string actually
// removes the text view from the toolbar

TextView toolbarTitle = null;
for (int i = 0; i < toolbar.getChildCount(); ++i) {
    View child = toolbar.getChildAt(i);

    // assuming that the title is the first instance of TextView
    // you can also check if the title string matches
    if (child instanceof TextView) {
        toolbarTitle = (TextView)child;
        break;
    }
}

布局:

<android.support.v7.widget.Toolbar
    android:id="@+id/toolbar_top"
    android:layout_height="wrap_content"
    android:layout_width="match_parent"
    android:minHeight="?attr/actionBarSize"
    android:background="@color/action_bar_bkgnd"
    app:theme="@style/ToolBarTheme" >

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

代码:

    Toolbar mToolbar = parent.findViewById(R.id.toolbar_top);
    TextView mToolbarCustomTitle = parent.findViewById(R.id.toolbar_title);

    //setup width of custom title to match in parent toolbar
    mToolbar.postDelayed(new Runnable()
    {
        @Override
        public void run ()
        {
            int maxWidth = mToolbar.getWidth();
            int titleWidth = mToolbarCustomTitle.getWidth();
            int iconWidth = maxWidth - titleWidth;

            if (iconWidth > 0)
            {
                //icons (drawer, menu) are on left and right side
                int width = maxWidth - iconWidth * 2;
                mToolbarCustomTitle.setMinimumWidth(width);
                mToolbarCustomTitle.getLayoutParams().width = width;
            }
        }
    }, 0);