Android 倒计时器 CountDownTimer 的使用

　　昨天的程序需求中需要一个倒计时器，我自己用TextView封装了一个，只是能用而已，今天早上发现Android 系统自己已经实现了一个，很好用，在这里记录一下，方便下次使用。

　　我自己封装的如下：

package com.hy.testfragment;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.widget.TextView;

public class HyTextViewTimer extends TextView {

    private int timer = -1;
    private Paint paint = new Paint();
    private HyEndOfTimerListener hyEndOfTimerListener = null;
    private MyThread th = null;

    Rect targetRect = new Rect(0, 0, 10, 10);

    private void init() {
        paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        paint.setStrokeWidth(3);
        paint.setTextSize(26);
        paint.setColor(Color.WHITE);
        paint.setTextAlign(Paint.Align.CENTER);
        setFocusable(true);
    }

    public HyTextViewTimer(Context context) {
        super(context);
        init();
    }

    public HyTextViewTimer(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public HyTextViewTimer(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init();
    }

    class MyThread extends Thread {
        HyTextViewTimer hyTextViewTimer = null;
        boolean bFlag = true;

        public MyThread(HyTextViewTimer hyTextViewTimer) {
            this.hyTextViewTimer = hyTextViewTimer;
            bFlag = true;
        }

        public void hy_stop() {
            bFlag = false;
        }

        @Override
        public void run() {
            while (bFlag) {
                this.hyTextViewTimer.postInvalidate();
                try {
                    for (int i = 0; i < 10; i++) {
                        Thread.sleep(100);
                        if(!bFlag) {
                            break;
                        }
                    }
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                if (timer >= 0) {
                    if (timer == 0 && hyEndOfTimerListener != null) {
                        if(bFlag) {
                            hyEndOfTimerListener.OnEnd();
                        }
                        break;
                    }
                    if(bFlag) {
                        timer--;
                    }
                }
            }
        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        targetRect.set(0, 0, getWidth(), getHeight());
        Paint.FontMetricsInt fontMetrics = paint.getFontMetricsInt();
        int baseline = (targetRect.bottom + targetRect.top - fontMetrics.bottom
                - fontMetrics.top) / 2;

        canvas.drawText(String.valueOf(timer < 0 ? 0 : timer),
                targetRect.centerX(), baseline, paint);

    }

    public interface HyEndOfTimerListener {
        /**
         * 倒计时结束时调用
         */
        void OnEnd();
    }


    public void setTimer(int value) {
        this.timer = value;
    }

    public void start() {
        if(th != null) {
            th.hy_stop();
            th = null;
        }

        th = new MyThread(this);
        th.start();
    }

    public void stop() {
        if(th != null) {
            th.hy_stop();
            th = null;
        }
    }

    public void setTextSize(int fontSize) {
        paint.setTextSize(fontSize);
    }

    public void setEndOfTimerListener(HyEndOfTimerListener hyEndOfTimerListener) {
        this.hyEndOfTimerListener = hyEndOfTimerListener;
    }

}

使用方法如下：

<com.hy.testfragment.HyTextViewTimer
    android:id="@+id/hyt"
    android:layout_width="250dp"
    android:layout_height="260dp"
    android:layout_marginLeft="100dp"
    android:textSize="25sp"/>

hyt = (HyTextViewTimer) findViewById(R.id.hyt);
hyt.setTextSize(80);
hyt.setEndOfTimerListener(new HyTextViewTimer.HyEndOfTimerListener() {
    @Override
    public void OnEnd() {
        //Toast.makeText(MainActivity.this, "the end", Toast.LENGTH_SHORT).show();
        System.out.println("---> the end");
        Message msg = handler.obtainMessage();

        handler.sendMessage(msg);
    }
});

// 开始使用
hyt.setTimer(9);

hyt.start();

// 停止使用
hyt.stop();

Android 系统自带的是 CountDownTimer, 使用方法如下：

private CountDownTimer timer = null;

public void btnStartClick(View view) throws Exception {
    if (timer != null) {
        timer.cancel();
        timer = null;
    }

    timer = new CountDownTimer(10000, 1000) {
        @Override
        public void onTick(long millisUntilFinished) {
            System.out.println((millisUntilFinished / 1000) + "秒后重发");
        }

        @Override
        public void onFinish() {
            Toast.makeText(MainActivity.this, "HHH CCC", Toast.LENGTH_SHORT).show();
        }
    };
    timer.start();
}

Android系统自带的 CountDownTimer 使用确实很方便。