Android自定义一个带缩放动画的倒计时View

为了方便修改字体样式，于是我继承了TextView。这个自定义的倒计时View，于是就是一个特别一点的TextView，用法和TextView一样。

以下是全部代码。需要注意的是，存在多个倒计时View时，应将Handler和TimeTask分离出来，重写代码。只使用一个线程进行倒计时，分发消息通知多个view更新时间文字。

import android.content.Context;
import android.graphics.Canvas;
import android.os.Build.VERSION_CODES;
import android.os.Handler;
import android.os.Message;
import android.support.annotation.Nullable;
import android.support.annotation.RequiresApi;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.View;
import android.view.animation.AccelerateInterpolator;
import android.view.animation.AlphaAnimation;
import android.view.animation.Animation;
import android.view.animation.AnimationSet;
import android.view.animation.ScaleAnimation;
import android.widget.TextView;

import java.util.Timer;
import java.util.TimerTask;

/**
* Created by Yue on 2017/7/18.
*/

public class TimeDownView extends TextView {
private Timer timer;
private DownTimerTask downTimerTask;
private int downCount;
private int lastDown;
private long intervalMills;
private long delayMills;
private AnimationSet animationSet;

public TimeDownView(Context context) {
this(context, null);
}

public TimeDownView(Context context, @Nullable AttributeSet attrs) {
this(context, attrs, 0);
}

public TimeDownView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}

@RequiresApi(api = VERSION_CODES.LOLLIPOP)
public TimeDownView(Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
init();
}

private void init() {
if (timer == null) {
timer = new Timer();
}
if (animationSet == null) {
animationSet = new AnimationSet(true);
}
if (downHandler == null){
downHandler = new DownHandler();
}
setGravity(Gravity.CENTER);
}

/**
* 开始计时
*
* @param seconds
*/
public void downSecond(int seconds) {
downTime(seconds, 0, 0, 1000);
}

/**
* 倒计时开启方法
*
* @param downCount     倒计时总数
* @param lastDown      显示的倒计时的最后一个数
* @param delayMills    延迟启动倒计时（毫秒数）
* @param intervalMills 倒计时间隔时间（毫秒数）
*/
public void downTime(int downCount, int lastDown, long delayMills, long intervalMills) {
this.downCount = downCount;
this.lastDown = lastDown;
this.delayMills = delayMills;
this.intervalMills = intervalMills;
initDefaultAnimate();

if (downTimerTask == null) {
downTimerTask = new DownTimerTask();
}
timer.schedule(downTimerTask, delayMills, intervalMills);

}

@Override
public void setVisibility(int visibility) {
super.setVisibility(visibility);
if (View.GONE == visibility) {
timer.cancel();
}
}

@Override
protected void onDraw(Canvas canvas) {
if (drawTextFlag == DRAW_TEXT_NO) {
return;
}
super.onDraw(canvas);
}

/**
* 取消
*/
public void cancel() {
timer.cancel();
}

private class DownTimerTask extends TimerTask {

@Override
public void run() {
if (downCount >= (lastDown - 1)) {
Message msg = Message.obtain();
msg.what = 1;
downHandler.sendMessage(msg);
}
}
}

public interface DownTimeWatcher {
void onTime(int num);

void onLastTime(int num);

void onLastTimeFinish(int num);
}

private DownTimeWatcher downTimeWatcher = null;

/**
* 监听倒计时的变化
*
* @param downTimeWatcher
*/
public void setOnTimeDownListener(DownTimeWatcher downTimeWatcher) {
this.downTimeWatcher = downTimeWatcher;
}
private DownHandler downHandler;

private class DownHandler extends Handler {
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
if (msg.what == 1) {
if (downTimeWatcher != null) {
downTimeWatcher.onTime(downCount);
}
if (downCount >= (lastDown - 1)) {
drawTextFlag = DRAW_TEXT_YES;//默认绘制

//未到结束时
if (downCount >= lastDown) {
setText(downCount + "");
startDefaultAnimate();
if (downCount == lastDown && downTimeWatcher != null) {
downTimeWatcher.onLastTime(downCount);
}
}

//到结束时
else if (downCount == (lastDown - 1)) {// 若lastDown为0，downCount == -1时是倒计时真正结束之时。
if (downTimeWatcher != null) {
downTimeWatcher.onLastTimeFinish(downCount);
}
//倒计时结束，虽然setText()方法触发onDraw，但重写使之不进行绘制
//设置不绘制标记
if (afterDownDimissFlag == AFTER_LAST_TIME_DIMISS) {
drawTextFlag = DRAW_TEXT_NO;
}
invalidate();//刷新一下
timer.cancel();
}
downCount--;
}
//
}
}
}
private final int DRAW_TEXT_YES = 1;
private final int DRAW_TEXT_NO = 0;
/**
* 是否执行onDraw的标识，默认绘制
*/
private int drawTextFlag = DRAW_TEXT_YES;

private final int AFTER_LAST_TIME_DIMISS = 1;
private final int AFTER_LAST_TIME_NODIMISS = 0;
/**
* 在倒计时结束之后文字是否消失的标志，默认消失
*/
private int afterDownDimissFlag = AFTER_LAST_TIME_DIMISS;

/**
* 设置倒计时结束后文字不消失
*/
public void setAfterDownNoDimiss() {
afterDownDimissFlag = AFTER_LAST_TIME_NODIMISS;
}

/**
* 设置倒计时结束后文字消失
*/
public void setAferDownDimiss() {
afterDownDimissFlag = AFTER_LAST_TIME_DIMISS;
}

private boolean startDefaultAnimFlag = true;

//关闭默认动画
public void closeDefaultAnimate() {
animationSet.reset();
startDefaultAnimFlag = false;
}
//开启默认动画
private void startDefaultAnimate() {
if (startDefaultAnimFlag) {
animationSet.startNow();
}
}

private void initDefaultAnimate() {
if (animationSet == null) {
animationSet = new AnimationSet(true);
}

ScaleAnimation scaleAnimation = new ScaleAnimation(1f, 0.5f, 1f, 0.5f, Animation.RESTART, 0.5f, Animation.RESTART, 0.5f);
scaleAnimation.setDuration(intervalMills);

AlphaAnimation alphaAnimation = new AlphaAnimation(1f, 0.3f);
alphaAnimation.setDuration(intervalMills);
//将AlphaAnimation这个已经设置好的动画添加到 AnimationSet中
animationSet.addAnimation(scaleAnimation);
animationSet.addAnimation(alphaAnimation);
animationSet.setInterpolator(new AccelerateInterpolator());
setAnimation(animationSet);
}

}

使用方式：

TimeDownView tdvDownTime = (TimeDownView)findViewById(R.id.xxx);
tdvDownTime.downSecond(10);//从10开始倒计时，一秒倒一次

如果要定义倒计时间隔时间，使用：

tdvDownTime.downTime(10, 0, 500, 1000);//从10开始倒计时， 到0结束；延迟500毫秒才开始倒计时，每1000毫秒倒一次。

如果要监听倒计时的变化，使用：

tdvDownTime.setOnTimeDownListener(new DownTimeWatcher() {
void onTime(int num){
}

void onLastTime(int num){
}

void onLastTimeFinish(int num){
}
}

);

缩放动画是默认开启的，可以关闭它：

tdvDownTime.closeDefaultAnimate();

——end