Android实现水波纹外扩效果的实例代码

微信曾经推出了一个查找附近好友的功能，大致功能是这样的：屏幕上有一个按钮，长按按钮的时候，会有一圈圈水波纹的动画向外扩散，松手后，动画结束。

现在简单来实现这样的一个动画功能：

思路: 主要用到了下面的蓝色的图片，定义三个ImageView，background都设置为蓝色的图片，然后定义一个包括缩放和透明度变化的动画集，然后每隔一段时间，让3个ImageView依次启动这个动画集，看起来就像蓝色的圆圈像水波纹向外扩散一样。

    

相关实现逻辑如下：

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
 android:layout_width="match_parent" 
 android:layout_height="match_parent" > 
 <ImageView 
 android:id="@+id/wave1" 
 android:layout_width="150dp" 
 android:layout_height="150dp" 
 android:layout_centerInParent="true" 
 android:background="@drawable/wave" 
 /> 
 <ImageView 
 android:id="@+id/wave2" 
 android:layout_width="150dp" 
 android:layout_height="150dp" 
 android:layout_centerInParent="true" 
 android:background="@drawable/wave"/> 
 <ImageView 
 android:id="@+id/wave3" 
 android:layout_width="150dp" 
 android:layout_height="150dp" 
 android:layout_centerInParent="true" 
 android:background="@drawable/wave" /> 
 <ImageView 
 android:id="@+id/normal" 
 android:layout_width="166dp" 
 android:layout_height="166dp" 
 android:layout_centerInParent="true" 
 android:background="@drawable/normal" /> 
</RelativeLayout> 

MainActivity.java

package com.jackie.waveanimation; 
import android.app.Activity; 
import android.os.Bundle; 
import android.os.Handler; 
import android.os.Message; 
import android.view.MotionEvent; 
import android.view.View; 
import android.view.animation.AlphaAnimation; 
import android.view.animation.AnimationSet; 
import android.view.animation.ScaleAnimation; 
import android.widget.ImageView; 
public class MainActivity extends Activity { 
 private ImageView mNormal, mWave1, mWave2, mWave3; 
 private AnimationSet mAnimationSet1, mAnimationSet2, mAnimationSet3; 
 private static final int OFFSET = 600; //每个动画的播放时间间隔 
 private static final int MSG_WAVE2_ANIMATION = 2; 
 private static final int MSG_WAVE3_ANIMATION = 3; 
 private Handler mHandler = new Handler() { 
 @Override 
 public void handleMessage(Message msg) { 
 switch (msg.what) { 
 case MSG_WAVE2_ANIMATION: 
 mWave2.startAnimation(mAnimationSet2); 
 break; 
 case MSG_WAVE3_ANIMATION: 
 mWave3.startAnimation(mAnimationSet3); 
 break; 
 } 
 } 
 }; 
 @Override 
 protected void onCreate(Bundle savedInstanceState) { 
 super.onCreate(savedInstanceState); 
 setContentView(R.layout.activity_main); 
 mNormal = (ImageView) findViewById(R.id.normal); 
 mWave1 = (ImageView) findViewById(R.id.wave1); 
 mWave2 = (ImageView) findViewById(R.id.wave2); 
 mWave3 = (ImageView) findViewById(R.id.wave3); 
 mAnimationSet1 = initAnimationSet(); 
 mAnimationSet2 = initAnimationSet(); 
 mAnimationSet3 = initAnimationSet(); 
 mNormal.setOnTouchListener(new View.OnTouchListener() { 
 @Override 
 public boolean onTouch(View v, MotionEvent event) { 
 switch (event.getAction()) { 
 case MotionEvent.ACTION_DOWN: 
 showWaveAnimation(); 
 break; 
 case MotionEvent.ACTION_UP: 
 clearWaveAnimation(); 
 break; 
 case MotionEvent.ACTION_CANCEL: 
 clearWaveAnimation(); 
 } 
 return true; 
 } 
 }); 
 } 
 private AnimationSet initAnimationSet() { 
 AnimationSet as = new AnimationSet(true); 
 ScaleAnimation sa = new ScaleAnimation(1f, 2.3f, 1f, 2.3f, 
 ScaleAnimation.RELATIVE_TO_SELF, 0.5f, 
 ScaleAnimation.RELATIVE_TO_SELF, 0.5f); 
 sa.setDuration(OFFSET * 3); 
 sa.setRepeatCount(Animation.INFINITE);// 设置循环 
 AlphaAnimation aa = new AlphaAnimation(1, 0.1f); 
 aa.setDuration(OFFSET * 3); 
 aa.setRepeatCount(Animation.INFINITE);//设置循环 
 as.addAnimation(sa); 
 as.addAnimation(aa); 
 return as; 
 } 
 private void showWaveAnimation() { 
 mWave1.startAnimation(mAnimationSet1); 
 mHandler.sendEmptyMessageDelayed(MSG_WAVE2_ANIMATION, OFFSET); 
 mHandler.sendEmptyMessageDelayed(MSG_WAVE3_ANIMATION, OFFSET * 2); 
 } 
 private void clearWaveAnimation() { 
 mWave1.clearAnimation(); 
 mWave2.clearAnimation(); 
 mWave3.clearAnimation(); 
 } 
} 

效果如下：

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