1.Handler2.Timer3.RxJava4.ValueAnimator5.其他

这些方式中，我选择了ValueAnimator,主要是它的API比较友好，不需要我们去封装太多东西,具体的使用方式我就不单独写了，下面的代码都有备注

代码实现：

package com.example.countdownview;import android.animation.Animator;import android.animation.AnimatorListenerAdapter;import android.animation.ValueAnimator;import android.content.Context;import android.content.res.TypedArray;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.RectF;import android.util.AttributeSet;import android.view.View;import android.view.animation.LinearInterpolator;public class CountDownView extends View {  //圆轮颜色  private int mRingColor;  //圆轮宽度  private float mRingWidth;  //宽度  private int mWidth;  //高度  private int mHeight;  private Paint mPaint;  //圆环的矩形区域  private RectF mRectF;  //  private int mCountdownTime;  private float mCurrentProgress;  private OnCountDownFinishListener mListener;  ValueAnimator valueAnimator;  public CountDownView(Context context) {    this(context, null);  }  public CountDownView(Context context, AttributeSet attrs) {    this(context, attrs, 0);  }  public CountDownView(Context context, AttributeSet attrs, int defStyleAttr) {    super(context, attrs, defStyleAttr);    TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CountDownView);    mRingColor = a.getColor(R.styleable.CountDownView_ringColor, Color.RED);    mCountdownTime = a.getInteger(R.styleable.CountDownView_countdownTime, 10);    mRingWidth=a.getDimension(R.styleable.CountDownView_ringWidth,2);    a.recycle();    mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);    /**     *圆环     */    //颜色    mPaint.setColor(mRingColor);    //空心    mPaint.setStyle(Paint.Style.STROKE);    mPaint.setAntiAlias(true); // 消除锯齿    //宽度    mPaint.setStrokeWidth(mRingWidth);  }  public void setCountdownTime(int mCountdownTime) {    this.mCountdownTime = mCountdownTime;  }  @Override  protected void onLayout(boolean changed, int left, int top, int right, int bottom) {    super.onLayout(changed, left, top, right, bottom);    mWidth = getMeasuredWidth();    mHeight = getMeasuredHeight();    mRectF = new RectF(0 + mRingWidth / 2, 0 + mRingWidth / 2,        mWidth - mRingWidth / 2, mHeight - mRingWidth / 2);  }  @Override  protected void onDraw(Canvas canvas) {    super.onDraw(canvas);    canvas.drawArc(mRectF, -90, mCurrentProgress, false, mPaint);  }  private ValueAnimator getValA(long countdownTime) {    ValueAnimator valueAnimator = ValueAnimator.ofFloat(0, 100);    valueAnimator.setDuration(countdownTime);    valueAnimator.setInterpolator(new LinearInterpolator());    valueAnimator.setRepeatCount(0);    return valueAnimator;  }  /**   * 开始倒计时   */  public void startCountDown() {    setClickable(false);    valueAnimator = getValA(mCountdownTime * 1000);    //状态更新监听    valueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {      @Override      public void onAnimationUpdate(ValueAnimator animation) {        float i = Float.valueOf(String.valueOf(animation.getAnimatedValue()));        mCurrentProgress = (int) (360 * (i / 100f));        invalidate();      }    });    valueAnimator.start();    //状态变化结束监听    valueAnimator.addListener(new AnimatorListenerAdapter() {      @Override      public void onAnimationEnd(Animator animation) {        super.onAnimationEnd(animation);        //倒计时结束回调        if (mListener != null) {          mListener.countDownFinished();        }        setClickable(true);      }    });  }  /**   * 恢复   */  public void resumeCountDown(){    if (valueAnimator!=null){      valueAnimator.resume();    }  }  /**   * 暂停   */  public void pauseCountDown(){    if (valueAnimator!=null){        valueAnimator.pause();    }  }  /**   * 停止倒计时   */  public void stopCountDown(){    if (valueAnimator!=null){      valueAnimator.cancel();    }  }  public void setCountDownFinishListener(OnCountDownFinishListener mListener) {    this.mListener = mListener;  }  public interface OnCountDownFinishListener {    void countDownFinished();  }}