水波纹的简介

其实就是自定义view，

然后通过触摸事件画一个圆

把圆放入一个集合，

在ondraw中便利集合中的圆，然后每一个根据本来的半径r和透明度不断地增加透明度和半径r，再次画出来

package com.minle.test;


import java.util.Timer;
import java.util.TimerTask;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;

public class MyView extends View {

	private int radius;
	private Paint paint;
	private float cx;
	private float cy;

	public MyView(Context context, AttributeSet attrs) {
		super(context, attrs);
		// TODO Auto-generated constructor stub
		// 获得自定义的属性，即获得自定义的半径
		TypedArray ta = context.obtainStyledAttributes(attrs,
				R.styleable.MyCircle);
		radius = ta.getInt(R.styleable.MyCircle_radius, 0);// 获得半径长度 默认0
		ta.recycle();// 关闭资源么
	}

	public MyView(Context context, AttributeSet attrs, int defStyleAttr) {
		super(context, attrs, defStyleAttr);
		// TODO Auto-generated constructor stub
	}

	public MyView(Context context) {
		super(context);
		// TODO Auto-generated constructor stub
	}

	@Override
	protected void onDraw(Canvas canvas) {
		paint = new Paint();
		paint.setColor(Color.RED);
		paint.setStyle(Style.STROKE);// //设置画笔为空心
		paint.setStrokeWidth(2);// 画笔线宽
		paint.setAntiAlias(true);// /抗锯齿
		canvas.drawCircle(cx, cy, radius, paint);
		super.onDraw(canvas);
	}
	@Override
	public boolean onTouchEvent(MotionEvent event) {
		// TODO Auto-generated method stub
		cx = event.getX();
		cy = event.getY();
		Timer timer = new Timer();
		timer.schedule(new TimerTask() {
			
			@Override
			public void run() {
				// TODO Auto-generated method stub
				
			}
		}, 0, 100);
		invalidate();//重新绘制此view
		return true;
	}
}

再在xml中布局就可以了