如何在 android 中设置 Styles.xml 的字体

Question

我有什么：

1. 我有一个自定义 class 继承 AppCompatTextView。
2. 我在 attires.xml 中定义了自定义属性 textformat 并且 我正在传递我需要从 xml
设置的字体

---

样式文件

<style name="HeaderFilterName">
        <item name="android:src">@drawable/back_button</item>
        <item name="android:text">@string/str_filter_edit</item>
        <item name="android:gravity">center</item>
        <item name="android:textSize">@dimen/Header_Filter_Name_Text_size</item>
        <item name="android:layout_weight">1</item>
    </style>

XML

    <customViews.CustomTftTextView
    android:id="@+id/txtScreenNameId"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    app:textformat="fonts/sf_san_fransisco.ttf"
    style="@style/HeaderFilterName"/>

attr.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="customfont">
        <attr name="textformat" format="string"/>
    </declare-styleable>
</resources>

CustomTftTextView.java

public class CustomTftTextView extends AppCompatTextView {
    private String text;

    public CustomTftTextView(final Context context) {
        this(context, null);
        Initialize(text,context);
    }

    public CustomTftTextView(final Context context, final AttributeSet attrs) {
        this(context, attrs, 0);
        text = context.getResources().obtainAttributes(attrs, R.styleable.customfont).getString(R.styleable.customfont_textformat);
        Initialize(text,context);
    }

    public CustomTftTextView(final Context context, final AttributeSet attrs, final int defStyle) {
        super(context, attrs, defStyle);
        text = context.getResources().obtainAttributes(attrs, R.styleable.customfont).getString(R.styleable.customfont_textformat);
        Initialize(text,context);
    }

    private void Initialize(String format, Context context) {

        Typeface mTypeface;
        if (format != null)
        {
            mTypeface = Typeface.createFromAsset(context.getAssets(), format);
        }
        else
        {
            mTypeface = Typeface.createFromAsset(context.getAssets(), "fonts/sf_san_fransisco.ttf");
        }
        setTypeface(mTypeface, Typeface.NORMAL);
        setLineSpacing(0.0f, 1.4f);
    }
}

---

虽然上面的代码工作完美，但如果我在 style 文件中移动 app:textformat，字体不会设置。

<style name="HeaderFilterName">
            <item name="android:src">@drawable/back_button</item>
            <item name="android:text">@string/str_filter_edit</item>
            <item name="textformat">@string/custom_font_medium </item>
<item name="android:gravity">center</item>
            <item name="android:textSize">@dimen/Header_Filter_Name_Text_size</item>
            <item name="android:layout_weight">1</item>
        </style>

strings.xml

<string name="custom_font_medium">fonts/sf_san_fransisco.ttf</string>

如何正确实现这一点

Answer 1

确保在 styles.xml 中使用了如下命名空间

<resources xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app='http://schemas.android.com/apk/res-auto'>

Answer 2

如果您查看 Resources#obtainAttributes() method 的文档，它说：

Retrieve a set of basic attribute values from an AttributeSet, not performing styling of them using a theme and/or style resources.

要获取应用了您的样式的属性，请改用 Context#obtainStyledAttributes() 方法。还建议保留对该 return 的引用，这样您可以在完成后 recycle() 它。例如：

TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.customfont);
text = a.getString(R.styleable.customfont_textformat);
a.recycle();