<?xml version="1.0" encoding="utf-8"?><resources>  <declare-styleable name="CountDownView">    <!--顏色-->    <attr name="ringColor" format="color" />    <!-- 進度文本的字體大小 -->    <attr name="progressTextSize" format="dimension" />    <!-- 圓環寬度 -->    <attr name="ringWidth" format="float" />    <!--進度文本顏色-->    <attr name="progressTextColor" format="color"/>    <!--倒計時-->    <attr name="countdownTime" format="integer"/>  </declare-styleable></resources>

import android.content.Context;/** * Created by 王 on 2017/10/21. */public class DisplayUtil {  /**   * 將px裝換成dp，保證尺寸不變   * @param context   * @param pxValue   * @return   */  public static int px2dp(Context context, float pxValue){    float density = context.getResources().getDisplayMetrics().density;//得到設備的密度    return (int) (pxValue/density+0.5f);  }  public static int dp2px(Context context,float dpValue){    float density = context.getResources().getDisplayMetrics().density;    return (int) (dpValue*density+0.5f);  }  public static int px2sp(Context context,float pxValue){    float scaleDensity = context.getResources().getDisplayMetrics().scaledDensity;//縮放密度    return (int) (pxValue/scaleDensity+0.5f);  }  public static int sp2px(Context context,float spValue) {    float scaleDensity = context.getResources().getDisplayMetrics().scaledDensity;    return (int) (spValue*scaleDensity+0.5f);  }}

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.Paint;import android.graphics.RectF;import android.util.AttributeSet;import android.view.View;import android.view.animation.LinearInterpolator;/** * Created by 王 on 2017/10/21. */public class CountDownView extends View{  //圓輪顏色  private int mRingColor;  //圓輪寬度  private float mRingWidth;  //圓輪進度值文本大小  private int mRingProgessTextSize;  //寬度  private int mWidth;  //高度  private int mHeight;  private Paint mPaint;  //圓環的矩形區域  private RectF mRectF;  //  private int mProgessTextColor;  private int mCountdownTime;  private float mCurrentProgress;  private OnCountDownFinishListener mListener;  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, context.getResources().getColor(R.color.colorAccent));    mRingWidth = a.getFloat(R.styleable.CountDownView_ringWidth, 40);    mRingProgessTextSize = a.getDimensionPixelSize(R.styleable.CountDownView_progressTextSize, DisplayUtil.sp2px(context, 20));    mProgessTextColor = a.getColor(R.styleable.CountDownView_progressTextColor, context.getResources().getColor(R.color.colorAccent));    mCountdownTime = a.getInteger(R.styleable.CountDownView_countdownTime, 10);    a.recycle();    mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);    mPaint.setAntiAlias(true);    this.setWillNotDraw(false);  }  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);    /**     *圓環     */    //顏色    mPaint.setColor(mRingColor);    //空心    mPaint.setStyle(Paint.Style.STROKE);    //寬度    mPaint.setStrokeWidth(mRingWidth);    canvas.drawArc(mRectF, -90, mCurrentProgress - 360, false, mPaint);    //繪制文本    Paint textPaint = new Paint();    textPaint.setAntiAlias(true);    textPaint.setTextAlign(Paint.Align.CENTER);    String text = mCountdownTime - (int) (mCurrentProgress / 360f * mCountdownTime) + "";    textPaint.setTextSize(mRingProgessTextSize);    textPaint.setColor(mProgessTextColor);    //文字居中顯示    Paint.FontMetricsInt fontMetrics = textPaint.getFontMetricsInt();    int baseline = (int) ((mRectF.bottom + mRectF.top - fontMetrics.bottom - fontMetrics.top) / 2);    canvas.drawText(text, mRectF.centerX(), baseline, textPaint);  }  private ValueAnimator getValA(long countdownTime) {    ValueAnimator valueAnimator = ValueAnimator.ofFloat(0, 100);    valueAnimator.setDuration(countdownTime);    valueAnimator.setInterpolator(new LinearInterpolator());    valueAnimator.setRepeatCount(0);    return valueAnimator;  }  /**   * 開始倒計時   */  public void startCountDown() {    setClickable(false);    ValueAnimator valueAnimator = getValA(mCountdownTime * 1000);    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();    valueAnimator.addListener(new AnimatorListenerAdapter() {      @Override      public void onAnimationEnd(Animator animation) {        super.onAnimationEnd(animation);        //倒計時結束回調        if (mListener != null) {          mListener.countDownFinished();        }        setClickable(true);      }    });  }  public void setAddCountDownListener(OnCountDownFinishListener mListener) {    this.mListener = mListener;  }  public interface OnCountDownFinishListener {    void countDownFinished();  }}

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  xmlns:app="http://schemas.android.com/apk/res-auto"  xmlns:tools="http://schemas.android.com/tools"  android:layout_width="match_parent"  android:layout_height="match_parent"  tools:context="com.example.circulardemo.MainActivity">  <com.example.circulardemo.CountDownView    android:id="@+id/cdv"    android:layout_width="50dp"    android:layout_height="50dp"    android:layout_centerVertical="true"    android:layout_centerHorizontal="true" /></RelativeLayout>

import android.os.Bundle;import android.support.v7.app.AppCompatActivity;public class MainActivity extends AppCompatActivity {  @Override  protected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    setContentView(R.layout.activity_main);    CountDownView countDownView = (CountDownView) findViewById(R.id.cdv);    //啟動    countDownView.startCountDown();    countDownView.setAddCountDownListener(new CountDownView.OnCountDownFinishListener() {      @Override      public void countDownFinished() {        Toast.makeText(MainActivity.this, "倒計時結束", Toast.LENGTH_SHORT).show();      }    });  }}