可以将可绘制的形状（带角的矩形）设置为视图的背景。

<TextView android:background="@drawable/frame"/>

矩形可绘制框架.xml（放入res/drawable文件夹）：

<shape
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle" >
    <solid android:color="@android:color/white" />
    <stroke android:width="1dip"
     android:color="#3d4caf"/>
    <corners android:radius="50dp"/>
</shape>

这可能会对你有所帮助。

<RelativeLayout
    android:id="@+id/textbox"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:layout_centerVertical="true"
    android:background="@android:color/darker_gray" >

    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:layout_margin="3dp"
        android:background="@android:color/white"
        android:gravity="center"
        android:text="@string/app_name"
        android:textSize="20dp" />

</RelativeLayout

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

我通过扩展文本视图并手动绘制边框解决了这个问题。我甚至添加了这样的选项，您可以选择边框是虚线还是虚线。

public class BorderedTextView extends TextView {
        private Paint paint = new Paint();
        public static final int BORDER_TOP = 0x00000001;
        public static final int BORDER_RIGHT = 0x00000002;
        public static final int BORDER_BOTTOM = 0x00000004;
        public static final int BORDER_LEFT = 0x00000008;

        private Border[] borders;

        public BorderedTextView(Context context, AttributeSet attrs, int defStyle) {
            super(context, attrs, defStyle);
            init();
        }

        public BorderedTextView(Context context, AttributeSet attrs) {
            super(context, attrs);
            init();
        }

        public BorderedTextView(Context context) {
            super(context);
            init();
        }
        private void init(){
            paint.setStyle(Paint.Style.STROKE);
            paint.setColor(Color.BLACK);
            paint.setStrokeWidth(4);        
        }
        @Override
        protected void onDraw(Canvas canvas) {
            super.onDraw(canvas);
            if(borders == null) return;

            for(Border border : borders){
                paint.setColor(border.getColor());
                paint.setStrokeWidth(border.getWidth());

                if(border.getStyle() == BORDER_TOP){
                    canvas.drawLine(0, 0, getWidth(), 0, paint);                
                } else
                if(border.getStyle() == BORDER_RIGHT){
                    canvas.drawLine(getWidth(), 0, getWidth(), getHeight(), paint);
                } else
                if(border.getStyle() == BORDER_BOTTOM){
                    canvas.drawLine(0, getHeight(), getWidth(), getHeight(), paint);
                } else
                if(border.getStyle() == BORDER_LEFT){
                    canvas.drawLine(0, 0, 0, getHeight(), paint);
                }
            }
        }

        public Border[] getBorders() {
            return borders;
        }

        public void setBorders(Border[] borders) {
            this.borders = borders;
        }
}

边框类：

public class Border {
    private int orientation;
    private int width;
    private int color = Color.BLACK;
    private int style;
    public int getWidth() {
        return width;
    }
    public void setWidth(int width) {
        this.width = width;
    }
    public int getColor() {
        return color;
    }
    public void setColor(int color) {
        this.color = color;
    }
    public int getStyle() {
        return style;
    }
    public void setStyle(int style) {
        this.style = style;
    }
    public int getOrientation() {
        return orientation;
    }
    public void setOrientation(int orientation) {
        this.orientation = orientation;
    }
    public Border(int Style) {
        this.style = Style;
    }
}

希望这对某人有所帮助：）

在xml文本视图上设置背景，

将roundd_textview.xml文件添加到可绘制目录中。

<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle" >
   <solid android:color="@android:color/white" />
   <stroke android:width="2dip" android:color="#4f5g52"/>
</shape>

在textView背景中设置可绘制文件。

我找到的最简单的解决方案（而且实际可行）：

<TextView
    ...
    android:background="@android:drawable/editbox_background" />