首先建立一個RingView.java

public class RingView extends View{

    //宣告變數
    private Paint paint;
    private Context context;

    public RingView(Context context) {
        super(context);
    }

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

    public RingView
 
(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }


    /*測量*/
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

    /*繪製*/
    @Override
 

    protected void onDraw(Canvas canvas) {
        //畫圓
        Paint big = new Paint();
        Paint moddle=new Paint();
        Paint small = new Paint();
        //獲得螢幕的寬高
        int width = canvas.getWidth() / 2;
        int height = canvas.getHeight() / 2;
        //設定顏色
        big.setColor(Color.BLUE);
        small.setColor(Color.BLUE);
        moddle.setColor(Color.WHITE);
        //清除鋸齒
 

        big.setAntiAlias(true);
        moddle.setAntiAlias(true);
        small.setAntiAlias(true);
        //畫布顏色
        canvas.drawColor(Color.WHITE);
        //畫圓
        canvas.drawCircle(width, height,160,big);
        canvas.drawCircle(width, height,110,moddle);
        canvas.drawCircle(width, height,60,small);
        //例項化一個畫筆
        Paint paint = new Paint();
        paint.setTextSize(10);
        paint.setColor(Color.WHITE);
        // 畫矩形(Rect)
        Rect rect = new Rect(170, width, 270, height);
        canvas.drawRect(rect, paint);
        super.onDraw(canvas);
    }

    /*定位*/
    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);
    }

}

在activity_main.XML中關聯RingView.java

<com.xxx.RingView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />