人生只是一种体验，不必用来演绎完美。

效果图

View源码

package com.android.circlescalebar.view;import android.animation.Animator;
import android.animation.AnimatorListenerAdapter;
import android.animation.ObjectAnimator;
import android.animation.ValueAnimator;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;
import android.view.animation.LinearInterpolator;import androidx.annotation.NonNull;import com.android.circlescalebar.utils.DensityUtils;
import java.util.ArrayList;
import java.util.List;
public final class WaveView extends View {private static final String TAG = "WaveView";private int centerColor  = Color.GREEN;private int centerRadius = DensityUtils.dp2px(1.0F);private int maxRadius = DensityUtils.dp2px(105.0F);private int waveIntervalTime= 500;private int waveDuration = 1500;private boolean running;private List<Wave> waveList = new ArrayList();;private int waveWidth = DensityUtils.dp2px(1.0F);private Paint paint = new Paint();public WaveView(Context context) {super(context);}public WaveView(Context context, AttributeSet attrs) {super(context, attrs);}public WaveView(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);}public void setWaveStart(boolean waveStart) {if (waveStart) {if (!running) {running = true;waveList.add(new Wave());}} else {running = false;for (Wave wave : waveList) {wave.cancelAnimation();}}}protected void onSizeChanged(int w, int h, int oldw, int oldh) {int radius = (int)((float)Math.min(w, h) / 2.0F);if (radius <maxRadius) {maxRadius = radius;}}protected void onDraw(Canvas canvas) {super.onDraw(canvas);paint.setColor(centerColor);for (Wave wave : waveList) {paint.setAlpha(wave.getAlpha());paint.setStrokeWidth((float)this.waveWidth);paint.setStyle(Paint.Style.STROKE);canvas.drawCircle((float)(this.getWidth() / 2), (float)(this.getHeight() / 2), wave.getCurrentRadius(),paint);}if (this.waveList.size() > 0) {paint.setAlpha(255);paint.setStyle(Paint.Style.FILL);canvas.drawCircle((float)(this.getWidth() / 2), (float)(this.getHeight() / 2), (float)this.centerRadius,paint);}}public final class Wave {public boolean hasCreateNewWave;public final ValueAnimator createWaveAnimation;public float percent;//        public final float getPercent() {
//            return percent;
//        }
//
//        public final void setPercent(float value) {
//
//            Log.d(TAG, "Wave: percent" + value);
//            percent = value;
//            if (running && value >= (float)waveIntervalTime / (float)waveDuration && !this.hasCreateNewWave) {
//                waveList.add(new Wave());
//                hasCreateNewWave = true;
//            }
//            invalidate();
//        }public void cancelAnimation() {createWaveAnimation.cancel();}public int getAlpha() {return (int)((float)255 * ((float)1 - percent));}public float getCurrentRadius() {return (float)centerRadius +percent * (float)(maxRadius - centerRadius);}public Wave() {
//            createWaveAnimation = ObjectAnimator.ofFloat(this, "percent", 0F, 1F);createWaveAnimation = ObjectAnimator.ofFloat(this, "alpha", 0F, 1F);createWaveAnimation.setInterpolator(new LinearInterpolator());createWaveAnimation.setDuration(waveDuration);createWaveAnimation.start();createWaveAnimation.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {@Overridepublic void onAnimationUpdate(@NonNull ValueAnimator valueAnimator) {float animatedValue = (float) valueAnimator.getAnimatedValue();percent = animatedValue;if (running && animatedValue >= (float)waveIntervalTime / (float)waveDuration && !hasCreateNewWave) {waveList.add(new Wave());hasCreateNewWave = true;}invalidate();}});createWaveAnimation.addListener(new AnimatorListenerAdapter() {@Overridepublic void onAnimationEnd(Animator animation) {super.onAnimationEnd(animation);waveList.remove(this);}});}}
}

工具类

package com.android.circlescalebar.utils;import android.content.res.Resources;public class DensityUtils {public float density;public DensityUtils() {density = Resources.getSystem().getDisplayMetrics().density;}/*** 根据手机的分辨率从 dp 的单位 转成为 px(像素)* @param dpValue 虚拟像素* @return 像素*/public static int dp2px(float dpValue) {return (int) (0.5f + dpValue * Resources.getSystem().getDisplayMetrics().density);}/*** 根据手机的分辨率从 px(像素) 的单位 转成为 dp* @param pxValue 像素* @return 虚拟像素*/public static float px2dp(int pxValue) {return (pxValue / Resources.getSystem().getDisplayMetrics().density);}/*** 根据手机的分辨率从 dp 的单位 转成为 px(像素)* @param dpValue 虚拟像素* @return 像素*/public int dip2px(float dpValue) {return (int) (0.5f + dpValue * density);}/*** 根据手机的分辨率从 px(像素) 的单位 转成为 dp* @param pxValue 像素* @return 虚拟像素*/public float px2dip(int pxValue) {return (pxValue / density);}
}

调用实现

 waveView.setWaveStart(true); 

布局

<com.android.circlescalebar.view.WaveViewandroid:id="@+id/waveView"android:layout_width="215dp"android:layout_height="215dp"android:layout_gravity="center"/>