仿支付宝统计饼状图的自定义view，如下图：

项目地址：https://github.com/bigeyechou/CustomViewCollection
目录：customviewcollection/app/src/main/java/com/bigeye/customviewcollection/customview/PieChartView.java

效果图：

源代码：

/**
 * 饼状图
 */
public class PieChartView extends View {

  private Paint paintChart, paintText, paintLine, paintMasking;
  private RectF mRectF = new RectF();
  //饼状图的数据（如：name、value数值、颜色等）
  private List<PieData> mPieDatas = new ArrayList<>();
  //总数，方便算百分比
  private float mSumValue;
  //半径
  private int radius;
  //直径
  private int diameter;
  //中心坐标
  private int centerX, centerY;
  //间隔的距离
  private float space;

  private boolean showTip;
  private int tipSize;
  private boolean openAnimation;
  private ValueAnimator mAnimator;

  // 默认的动效周期 2s
  private int defaultDuration = 1000;
  //动画的执行的百分比mAnimatorValue
  private float mAnimatorValue = 1f;

  public PieChartView(Context context) {
    super(context);
    initAll();
  }

  public PieChartView(Context context, @Nullable AttributeSet attrs) {
    this(context, attrs, 0);
  }

  public PieChartView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.PieChartView, defStyleAttr, 0);
    diameter = typedArray.getDimensionPixelSize(R.styleable.PieChartView_pie_size, 0);
    space = typedArray.getFloat(R.styleable.PieChartView_pie_space, 0f);
    openAnimation = typedArray.getBoolean(R.styleable.PieChartView_open_animation, false);
    showTip = typedArray.getBoolean(R.styleable.PieChartView_show_tip, false);
    tipSize = showTip?100:0;//如果显示tip，则预留出tip控件的间距
    typedArray.recycle();
    initAll();
  }

  private void initAll() {
    initPain();
    if (openAnimation) {
      startAnimation();
    }
  }

  private void initPain() {
    paintChart = new Paint();
    paintChart.setAntiAlias(true);
    paintChart.setColor(Color.BLACK);

    paintMasking = new Paint();
    paintMasking.setColor(Color.WHITE);
    paintMasking.setStyle(Paint.Style.FILL);
    paintMasking.setAntiAlias(true);

    paintLine = new Paint();
    paintLine.setStyle(Paint.Style.STROKE);
    paintLine.setStrokeWidth(5);
    paintLine.setAntiAlias(true);

    paintText = new Paint();
    paintText.setColor(Color.BLACK);
    paintText.setStyle(Paint.Style.FILL);
    paintText.setStrokeWidth(20);
    paintText.setTextSize(30);
  }

  /**
   * 设置数据源
   * @param pieData 饼状图的数据
   */
  public void setPieData(List<PieData> pieData) {
    if (pieData.size() > 0) {
      mPieDatas = pieData;
      if (mPieDatas.size() > 0) {
        int sumValue = 0;
        for (PieData data : mPieDatas) {
          sumValue += data.getValue();
        }
        mSumValue = sumValue;
      }
    }
  }

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

  @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    super.onSizeChanged(w, h, oldw, oldh);
    //设置尺寸，没有设置pie_size或者设置的size + 预留给tip控件的距离>=最小边时不使用xml里设置的直径尺寸
    if (diameter <= 0 || diameter+tipSize >= getWidth() || diameter+tipSize >= getHeight()) {
      diameter = (getWidth() > getHeight() ? getHeight() : getWidth()) - tipSize;
    }
    radius = diameter / 2;
    centerX = getWidth() / 2;
    centerY = getHeight() / 2;
    mRectF.set(centerX - radius, centerY - radius, centerX + radius, centerY + radius);
  }
  
  private float startAngle = -90;
  private float sweepAngle;

  @Override protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    if (mPieDatas == null || mPieDatas.size() <= 0) {
      canvas.drawArc(mRectF, 0, 360, true, paintChart);
      canvas.drawCircle(centerX, centerY, radius / 2, paintMasking);
      return;
    }
    for (PieData data : mPieDatas) {
      paintChart.setColor(data.getColor());
      paintLine.setColor(data.getColor());
      sweepAngle = (data.getValue() / mSumValue) * 360f;
      canvas.drawArc(mRectF, startAngle, sweepAngle * mAnimatorValue - space, true, paintChart);
      if (showTip) {
        //是否画标签说明的小部件
        drawTip(canvas, data);
      }
      startAngle += sweepAngle;
    }
    canvas.drawCircle(centerX, centerY, radius / 2, paintMasking);
  }

  /**
   * 画tip控件
   */
  private void drawTip(Canvas canvas, PieData data) {
    Path pathLine = new Path();
    PathMeasure measure = new PathMeasure();

    float textPadding = 10;
    float textHigh = (paintText.getFontMetrics().bottom - paintText.getFontMetrics().top) / 2;
    float padding = 20;
    float dotSize = 10;
    float dotX = (float) (centerX + (radius + padding) * Math.cos(Math.toRadians((startAngle + sweepAngle / 2))));
    float dotY = (float) (centerY + (radius + padding) * Math.sin(Math.toRadians((startAngle + sweepAngle / 2))));

    float lineX = (float) (centerX + (radius + padding * 2) * Math.cos(Math.toRadians((startAngle + sweepAngle / 2))));
    float lineY = (float) (centerY + (radius + padding * 2) * Math.sin(Math.toRadians((startAngle + sweepAngle / 2))));
    canvas.drawCircle(dotX, dotY, dotSize, paintChart);

    if (dotX > centerX) {
      //右侧
      pathLine.moveTo(dotX, dotY);
      pathLine.lineTo(lineX, lineY);
      pathLine.lineTo(getRight(), lineY);
      measure.setPath(pathLine, false);
      Path dst = new Path();
      measure.getSegment(0, measure.getLength() * mAnimatorValue, dst, true);
      canvas.drawPath(dst, paintLine);

      if (mAnimatorValue == 1) {
        paintText.setTextAlign(Paint.Align.RIGHT);
        canvas.drawText((data.getValue() / mSumValue) * 100 + "%", getWidth() - textPadding, lineY - textPadding, paintText);
        canvas.drawText(data.getName(), getWidth() - textPadding, lineY + textHigh + textPadding, paintText);
      }
    } else {
      //左侧
      measure = new PathMeasure();
      pathLine.moveTo(dotX, dotY);
      pathLine.lineTo(lineX, lineY);
      pathLine.lineTo(0, lineY);
      measure.setPath(pathLine, false);
      Path dst = new Path();
      measure.getSegment(0, measure.getLength() * mAnimatorValue, dst, true);
      canvas.drawPath(dst, paintLine);

      if (mAnimatorValue == 1) {
        paintText.setTextAlign(Paint.Align.LEFT);
        canvas.drawText((data.getValue() / mSumValue) * 100 + "%", 0 + textPadding, lineY - textPadding, paintText);
        canvas.drawText(data.getName(), 0 + textPadding, lineY + textHigh + textPadding, paintText);
      }
    }
  }

  /**
   * 开启动画
   */
  private void startAnimation() {
    mAnimator = ValueAnimator.ofFloat(0, 1).setDuration(defaultDuration);
    mAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
      @Override public void onAnimationUpdate(ValueAnimator valueAnimator) {
        mAnimatorValue = (float) valueAnimator.getAnimatedValue();
        invalidate();
      }
    });
    mAnimator.start();
  }

}

attrs 属性文件：

    <!-- 饼状图 -->
    <declare-styleable name="PieChartView">
        <attr name="pie_size" format="dimension"/><!-- 饼状图的直径 -->
        <attr name="pie_space" format="float"/><!-- 饼状图间隔尺寸 -->
        <attr name="open_animation" format="boolean"/><!-- 是否开启动画 -->
        <attr name="show_tip" format="boolean"/><!-- 是否显示提示说明的线 -->
    </declare-styleable>

xml 布局文件：

    <com.bigeye.customviewcollection.customview.PieChartView
        android:id="@+id/pie_char"
        android:layout_width="match_parent"
        android:layout_height="200dp"
        app:pie_size="190dp"
        app:pie_space="2"
        app:show_tip="true"
        app:open_animation="true"
        android:visibility="visible"/>

自定义一个PieData，设置相关属性， pieChartView.setPieData(datas);