public class WaterWaveView2 extends View {

  //存放圓環(huán)的集合
  private ArrayList<Wave> mList;

  //界面刷新
  private Handler mHandler = new Handler() {
    @Override
    public void handleMessage(Message msg) {
      invalidate();//刷新界面,會執(zhí)行onDraw方法
    }
  };

  public WaterWaveView2(Context context) {
    this(context, null);
  }

  public WaterWaveView2(Context context, AttributeSet attrs) {
    super(context, attrs);
    mList = new ArrayList<Wave>();
  }

/**
* Created by HongJay on 2016/8/30.
* 把wave的數(shù)據(jù)封裝成一個對象
*/
public class Wave {
  public float x;//圓心x坐標
  public float y;//圓心y坐標
  public Paint paint; //畫圓的畫筆
  public float width; //線條寬度
  public int radius; //圓的半徑
  public int ranNum;//隨機數(shù)
  public int[] randomColor={Color.BLUE,Color.CYAN,
      Color.GREEN,Color.MAGENTA,Color.RED,Color.YELLOW};

  public Wave(float x, float y) {
    this.x = x;
    this.y = y;
    initData();
  }
  /**
   * 初始化數(shù)據(jù),每次點擊一次都要初始化一次
   */
  private void initData() {
    paint=new Paint();//因為點擊一次需要畫出不同的圓環(huán)
    paint.setAntiAlias(true);//打開抗鋸齒
    ranNum=(int) (Math.random()*6);//[0,5]的隨機數(shù)
    paint.setColor(randomColor[ranNum]);//設置畫筆的顏色
    paint.setStyle(Paint.Style.STROKE);//描邊
    paint.setStrokeWidth(width);//設置描邊寬度
    paint.setAlpha(255);//透明度的設置(0-255),0為完全透明
    radius=0;//初始化
    width=0;
  }
}

public boolean onTouchEvent(MotionEvent event) {
    super.onTouchEvent(event);
    switch (event.getAction()) {
      case MotionEvent.ACTION_DOWN:

        float x = event.getX();
        float y = event.getY();
        deleteItem();
        Wave wave = new Wave(x, y);
        mList.add(wave);

        //刷新界面
        invalidate();
        break;

      case MotionEvent.ACTION_MOVE:
        float x1 = event.getX();
        float y1 = event.getY();
        deleteItem();
        Wave wave1 = new Wave(x1, y1);
        mList.add(wave1);

        invalidate();
        break;
    }
    //處理事件
    return true;
  }
  //刪除透明度已經(jīng)為0的圓環(huán)
  private void deleteItem(){
    for (int i = 0; i <mList.size() ; i++) {
      if(mList.get(i).paint.getAlpha()==0){
        mList.remove(i);
      }
    }
  }
}

protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);

    //避免程序一運行就進行繪制
    if (mList.size() > 0) {

      //對集合中的圓環(huán)對象循環(huán)繪制
      for (Wave wave : mList) {
        canvas.drawCircle(wave.x, wave.y, wave.radius, wave.paint);
        wave.radius += 3;
        //對畫筆透明度進行操作
        int alpha = wave.paint.getAlpha();
        if (alpha < 80) {
          alpha = 0;
        } else {
          alpha -= 3;
        }

        //設置畫筆寬度和透明度
        wave.paint.setStrokeWidth(wave.radius / 8);
        wave.paint.setAlpha(alpha);

        //延遲刷新界面
        mHandler.sendEmptyMessageDelayed(1, 100);
      }
    }
  }