//1.画圆环
//原点坐标
float circleX = width / 2;
float circleY = width / 2;
//半径
float radius = width / 2 - roundWidth / 2;

//设置画笔的属性
paint.setColor(roundColor);
paint.setStrokeWidth(roundWidth);
paint.setStyle(Paint.Style.STROKE);

canvas.drawCircle(circleX, circleY, radius, paint);

//2.画圆弧
RectF oval = new RectF(roundWidth/2,roundWidth/2,width-roundWidth/2,width - roundWidth/2);

paint.setColor(roundProgressColor);

canvas.drawArc(oval, 0, progress * 360 / max, false, paint);

//3.画文本
paint.setTextSize(textSize);
paint.setColor(textColor);
paint.setStrokeWidth(0);
String text = progress * 100 / max + "%";
Rect bounds = new Rect();
paint.getTextBounds(text, 0, text.length(), bounds);

canvas.drawText(text, width / 2 - bounds.width() / 2, width / 2 + bounds.height() / 2, paint);

<declare-styleable name="RoundProgress">
 <attr name="roundColor" format="color"></attr>
 <attr name="roundProgressColor" format="color"></attr>
 <attr name="textColor" format="color"></attr>
 <attr name="roundWidth" format="dimension"></attr>
 <attr name="textSize" format="dimension"></attr>
</declare-styleable>

xmlns:atguigu="http://schemas.android.com/apk/res-auto"

<com.atguigu.p2p.util.RoundProgress
    android:id="@+id/rp_home_progress"
    android:layout_width="120dp"
    android:layout_height="120dp"
    android:layout_gravity="center_horizontal"
    android:layout_marginTop="20dp"
    atguigu:roundColor="@android:color/darker_gray                  
    atguigu:roundProgressColor="@android:color/holo_red_dark"
    atguigu:textColor="@color/text_progress"
    atguigu:roundWidth="10dp"
    atguigu:textSize="20sp"
    />    

//1.得到所有自定义属性的数组
TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.RoundProgress);
//2.获取自定义属性的值, 如果没有指定取默认值
roundColor = typedArray.getColor(R.styleable.RoundProgress_roundColor, Color.RED);
roundProgressColor = typedArray.getColor(R.styleable.RoundProgress_roundProgressColor, Color.GREEN);
textColor = typedArray.getColor(R.styleable.RoundProgress_textColor, Color.GREEN);
roundWidth = typedArray.getDimension(R.styleable.RoundProgress_roundWidth, UIUtils.dp2px(10));
textSize = typedArray.getDimension(R.styleable.RoundProgress_textSize, UIUtils.dp2px(20));
//3.释放资源数据
typedArray.recycle();