自定义属性

目录：res/attrs.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="Divider">
        <attr name="android:orientation" />
        <attr name="android:background" />
    </declare-styleable>
</resources>

代码实现

/**
 * 自定义控件：分割线
 */
public class Divider extends View {

    private int orientation;
    private Drawable background;

    public Divider(Context context) {
        this(context, null);
    }

    public Divider(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        TypedArray attributes = context.obtainStyledAttributes(attrs, R.styleable.Divider);
        orientation = attributes.getInt(R.styleable.Divider_android_orientation, 0);
        background = attributes.getDrawable(R.styleable.Divider_android_background);
        background = (background == null) ? new ColorDrawable(Color.WHITE) : background;
        attributes.recycle();
    }

    @Override
    protected void onAttachedToWindow() {
        super.onAttachedToWindow();
        ViewGroup.LayoutParams layoutParams = getLayoutParams();
        int wrapContent = ViewGroup.LayoutParams.WRAP_CONTENT;
        int matchParent = ViewGroup.LayoutParams.MATCH_PARENT;

        int width = layoutParams.width;
        int height = layoutParams.height;

        if (orientation == LinearLayout.HORIZONTAL) {
            // 水平方向
            layoutParams.width = (width == wrapContent) ? matchParent : width;
            layoutParams.height = (height == wrapContent) ? 1 : height; // 1px
        } else {
            // 垂直方向
            layoutParams.width = (width == wrapContent) ? 1 : width; // 1px
            layoutParams.height = (height == wrapContent) ? matchParent : height;
        }
        this.setBackground(background);
        this.requestLayout();
    }
}

使用示例

<com.haoxueren.view.Divider
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@color/colorWhite"
    android:orientation="horizontal"
    app:layout_constraintLeft_toLeftOf="parent"
    app:layout_constraintTop_toTopOf="@id/webViewLayout" />