我找到了一种更好的方法来在TextView周围添加边框。

使用九块图像作为背景。它非常简单，SDK附带了一个制作9补丁图像的工具，而且它绝对不需要编码。

链接是http://developer.android.com/guide/topics/graphics/2d-graphics.html#nine-补丁。

可以通过两种方法设置边框。一种是可绘制的，另一种是编程的。

使用Drawable

<shape>
    <solid android:color="@color/txt_white"/>
    <stroke android:width="1dip" android:color="@color/border_gray"/>
    <corners android:bottomLeftRadius="10dp"
             android:bottomRightRadius="0dp"
             android:topLeftRadius="10dp"
             android:topRightRadius="0dp"/>
    <padding android:bottom="0dip"
             android:left="0dip"
             android:right="0dip"
             android:top="0dip"/>
</shape>

程序化的

public static GradientDrawable backgroundWithoutBorder(int color) {

    GradientDrawable gdDefault = new GradientDrawable();
    gdDefault.setColor(color);
    gdDefault.setCornerRadii(new float[] { radius, radius, 0, 0, 0, 0,
                                           radius, radius });
    return gdDefault;
}

更改康斯坦丁·布罗夫的答案，因为在我的情况下不起作用：

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item>
        <shape android:shape="rectangle">
            <solid android:color="@android:color/white" />
            <stroke android:width="2dip" android:color="#4fa5d5"/>
            <corners android:radius="7dp"/>
        </shape>
    </item>
</selector>

compileSdkVersion 26（Android 8.0），minSdkVersion 21（Android 5.0），targetSdkV版本26，实现“com.android.support:appcompat-v7:26.1.0”，等级：4.1

这是我的“简单”助手类，它返回带有边框的ImageView。只需将其放在utils文件夹中，并按如下方式调用：

ImageView selectionBorder = BorderDrawer.generateBorderImageView(context, borderWidth, borderHeight, thickness, Color.Blue);

这是代码。

/**
 * Because creating a border is Rocket Science in Android.
 */
public class BorderDrawer
{
    public static ImageView generateBorderImageView(Context context, int borderWidth, int borderHeight, int borderThickness, int color)
    {
        ImageView mask = new ImageView(context);

        // Create the square to serve as the mask
        Bitmap squareMask = Bitmap.createBitmap(borderWidth - (borderThickness*2), borderHeight - (borderThickness*2), Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(squareMask);

        Paint paint = new Paint();
        paint.setStyle(Paint.Style.FILL);
        paint.setColor(color);
        canvas.drawRect(0.0f, 0.0f, (float)borderWidth, (float)borderHeight, paint);

        // Create the darkness bitmap
        Bitmap solidColor = Bitmap.createBitmap(borderWidth, borderHeight, Bitmap.Config.ARGB_8888);
        canvas = new Canvas(solidColor);

        paint.setStyle(Paint.Style.FILL);
        paint.setColor(color);
        canvas.drawRect(0.0f, 0.0f, borderWidth, borderHeight, paint);

        // Create the masked version of the darknessView
        Bitmap borderBitmap = Bitmap.createBitmap(borderWidth, borderHeight, Bitmap.Config.ARGB_8888);
        canvas = new Canvas(borderBitmap);

        Paint clearPaint = new Paint();
        clearPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));

        canvas.drawBitmap(solidColor, 0, 0, null);
        canvas.drawBitmap(squareMask, borderThickness, borderThickness, clearPaint);

        clearPaint.setXfermode(null);

        ImageView borderView = new ImageView(context);
        borderView.setImageBitmap(borderBitmap);

        return borderView;
    }
}

您可以为文本视图创建自定义背景。步骤

转到您的项目。转到资源，右键单击可绘制。单击新建->可绘制资源文件为您的文件命名在文件中粘贴以下代码

<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <stroke
        android:width="1dp"
        android:color="@color/colorBlack" />
    <padding
        android:bottom="1dp"
        android:left="1dp"
        android:right="1dp"
        android:top="1dp" />
    <corners android:radius="6dp" />
    <solid android:color="#ffffffff" />
</shape>

对于要将其用作背景的文本视图，android：background=“@drawbable/your_fileName”

简单的方法是为TextView添加视图。底部边框线示例：

<LinearLayout android:orientation="vertical"
              android:layout_width="fill_parent"
              android:layout_height="fill_parent">
    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:layout_marginLeft="10dp"
        android:text="@string/title"
        android:id="@+id/title_label"
        android:gravity="center_vertical"/>
    <View
        android:layout_width="fill_parent"
        android:layout_height="0.2dp"
        android:id="@+id/separator"
        android:visibility="visible"
        android:background="@android:color/darker_gray"/>

</LinearLayout>

对于其他方向的边框，请调整分隔符视图的位置。