好久没有写博客了，趁着年末，总结了下最近一年所遇到的一些技术问题，还有一些自定义控件，比如倒计时功能

首先倒计时的实现方式

1.Handler
2.Timer
3.RxJava
4.ValueAnimator
5.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

项目地址

项目图片

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();
  }
}

总结

以上所述是小编给大家介绍的Android倒计时功能的实现代码，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对海外IDC网网站的支持！
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