首先自定义属性：

下面看看具体实现：

/** * Created by Michael on 2019/11/1. */ public class RatingStar extends View {   private int normalId;  private int focusId;  private Bitmap normalImg;  private Bitmap focusImg;  private int number;  private int w1;  private int h2;  private int marginLeft;  private int marginTop;  private int marginBottom;  private int marginRight;  private int height;  private int width;  private int p;  private float w0;  private int i0;  private int mGrade;   public RatingStar(Context context) {    this(context,null);  }   public RatingStar(Context context, @Nullable AttributeSet attrs) {    this(context, attrs,0);  }   public RatingStar(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {    super(context, attrs, defStyleAttr);    TypedArray array = context.obtainStyledAttributes(attrs,R.styleable.RatingStar);    normalId = array.getResourceId(R.styleable.RatingStar_starNormal,0);    focusId = array.getResourceId(R.styleable.RatingStar_starFocus,0);    normalImg = BitmapFactory.decodeResource(getResources(), normalId);    focusImg = BitmapFactory.decodeResource(getResources(), focusId);    number = array.getInteger(R.styleable.RatingStar_starNumber,5);    array.recycle();    i0 = -1;   }   @Override  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {    w1 = normalImg.getWidth();    h2 = normalImg.getHeight();    //中间间隔    p = 30;    marginTop = 20;    marginBottom = 20;    marginLeft = 20;    marginRight = 20;    height = h2 + marginTop + marginBottom;    width = w1 *number+(number-1)*p +marginLeft+marginRight;    setMeasuredDimension(width, height);  }   @Override  protected void onDraw(Canvas canvas) {    super.onDraw(canvas);    for (int i = 0; i < number; i++) {      if (i <= i0){        canvas.drawBitmap(focusImg,i*w1+marginLeft+i*p,marginTop,null);        mGrade = i+1;      }else{        canvas.drawBitmap(normalImg,i*w1+marginLeft+i*p,marginTop,null);      }    }    Log.e("msg","我被调用了！");   }   @Override  public boolean onTouchEvent(MotionEvent event) {    float x = event.getX();//相对于控件自身的距离    //event.getRawX() 相对于屏幕的距离    switch (event.getAction()){      case MotionEvent.ACTION_DOWN:      case MotionEvent.ACTION_MOVE:      //case MotionEvent.ACTION_UP:        w0 = getWidth()/5;        i0 = (int) (x/w0);        //性能优化，减少onDraw()调用        if (mGrade == i0+1){          return true;        }        invalidate();        break;    }    return true;  }}

最后看看具体布局中使用：