<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="带边框的文本"
        android:textSize="24pt"
        android:background="@drawable/bg_border"/>
    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="圆角边框"
        android:textSize="24pt"
        android:background="@drawable/bg_border2"/>

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <!--设置背景为透明色-->
    <solid android:color="#0000"/>
    <stroke android:width="4px"
            android:color="#f00"/>
</shape>

自定义背景bg_border2

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <!--圆角矩形的四个圆角-->
    <corners android:topLeftRadius="20px"
             android:topRightRadius="5px"
             android:bottomRightRadius="20px"
             android:bottomLeftRadius="5px"/>
    <!--指定边框的宽度和颜色-->
    <stroke android:width="4px" android:color="#f0f"/>
    <!--指定使用渐变背景色，使用sweep类型渐变，颜色从红色-》绿色-》蓝色-->
    <gradient android:startColor="#f00"
              android:centerColor="#0f0"
              android:endColor="#00f"
              android:type="sweep"/>
</shape>

public class MainActivity extends Activity
{

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