效果图：

封装好的工具类：TimeUtils.java

package com.xiao7.pump.Utils;

import android.os.Handler;

import android.os.Message;

import android.widget.TextView;

import java.util.Timer;

import java.util.TimerTask;

public class TimeUtils {

/*倒计时时长 单位：秒*/

public static int COUNT = 20*60;

/*当前做*/

private static int CURR_COUNT = 0;

/*预计结束的时间*/

private static long TIME_END = 0;

/*计时器*/

private static Timer countdownTimer;

/*显示倒计时的textView*/

private static TextView txtCountdown;

/**

* 开始倒计时

* @param isFirst 标识是否是第一次进入

* @param second 倒计时时长 单位：秒

* @param textView 显示倒计时的textView

*/

public static void startCountdown(boolean isFirst,int second,TextView textView) {

COUNT = second;

long data = System.currentTimeMillis();

long time = TIME_END;

//第一次进入时，重新赋值

if(isFirst){

CURR_COUNT = COUNT;

time = data + COUNT * 1000;

TIME_END = time;

}else {

int the_difference = ((int) (time - data)) / 1000;

CURR_COUNT = the_difference;

}

//开始倒计时

txtCountdown = textView;

if (countdownTimer == null) {

countdownTimer = new Timer();

countdownTimer.schedule(new TimerTask() {

@Override

public void run() {

Message msg = new Message();

msg.what = CURR_COUNT--;

handler.sendMessage(msg);

}

}, 0, 1000);

//第二个参数delay:"0"的意思是:无延迟

//第三个参数period:"1000"的意思是:每隔多长时间调用一次(单位毫秒)

}

}

/**

* 结束倒计时

*/

public static void stopCountdown() {

//发送消息，结束倒计时

Message message = new Message();

message.what = 0;

handler.sendMessage(message);

}

private static Handler handler = new Handler() {

public void handleMessage(Message msg) {

if (msg.what <= 0) {

if (countdownTimer != null) {

countdownTimer.cancel();

countdownTimer = null;

}

txtCountdown.setText("剩余：00:00:00");

txtCountdown.setEnabled(true);

} else {

//倒计时效果展示

String txtTime = formatSecondTime(msg.what);

txtCountdown.setText(txtTime);

txtCountdown.setEnabled(false);

}

super.handleMessage(msg);

}

};

/**

* 时间格式化方法

* @param second 秒数

* @return

*/

private static String formatSecondTime(int second) {

int hour = 0;

int minute = 0;

if (second > 60) {

minute = second / 60; //取整

second = second % 60; //取余

}

if (minute > 60) {

hour = minute / 60;

minute = minute % 60;

}

String strtime = "剩余："+hour+"小时"+minute+"分"+second+"秒";

return strtime;

}

}

TimeUtils调用方式：

//在启动倒计时的按钮上

buttonStart.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View view) {

//假设倒计20分钟

int secondTime=20*60;

//倒计时

TimeUtils.startCountdown(true,secondTime,txtCountDown);

//第一个参数为true,表示刚启动倒计时(第一次)

}

});

活动的生命周期onRestart()上重新调用，如下：

@Override

protected void onRestart() {

super.onRestart();

TimeUtils.startCountdown(false,secondTime,txtCountDown);

//第一个参数为false,表示非第一次启用，倒计时正在运行中

}