• 先上效果圖

- 倒計時結束

程式碼塊

attr.xml 控制元件需要用到的屬性：

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <declare-styleable name="CountDownView">
        <!--顏色-->
        <attr name="ringColor" format="color" />
        <!-- 進度文字的字型大小 -->
        <attr name
 
="progressTextSize" format="dimension" />
        <!-- 圓環寬度 -->
        <attr name="ringWidth" format="float" />
        <!--進度文字顏色-->
        <attr name="progressTextColor" format="color"/>
        <!--倒計時-->
        <attr name="countdownTime" format="integer"/>
    </declare-styleable
 
>
</resources>

CountDownView.java

public class CountDownView extends View {
    //圓輪顏色
    private int mRingColor;
    //圓輪寬度
    private float mRingWidth;
    //圓輪進度值文字大小
    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, DisplayUtils.sp2px(context, 20));
        mProgessTextColor = a.getColor(R.styleable.CountDownView_progressTextColor, context.getResources().getColor(R.color.colorAccent));
        mCountdownTime = a.getInteger(R.styleable.CountDownView_countdownTime, 60);
        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);
        //繪製文字
        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);
                //倒計時結束回撥
                if (mListener != null) {
                    mListener.countDownFinished();
                }
                setClickable(true);
            }

        });
    }
    public void setAddCountDownListener(OnCountDownFinishListener mListener) {
        this.mListener = mListener;
    }
    public interface OnCountDownFinishListener {
        void countDownFinished();
    }


}

MainActivity.java

package com.ouyuan.demo.myapplication;

import android.animation.ValueAnimator;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    CountDownView cdv;
    TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        cdv = (CountDownView) findViewById(R.id.countDownView);

        cdv.setAddCountDownListener(new CountDownView.OnCountDownFinishListener() {
            @Override
            public void countDownFinished() {
                Toast.makeText(MainActivity.this, "倒計時結束", Toast.LENGTH_SHORT).show();
            }
        });

        cdv.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                cdv.startCountDown();
            }
        });
    }
}