1.背景

还是音乐播放界面，实现倒计时和进度条功能，基本实现过程: 当打开MusicActivity 的时候，MusicService会发送广播给MusicActivity ，后开始当前播放的时间进度，从而实现倒计时和进度条；

这里说明下 进度条是 从小到大 ，倒计时是 从大到小 ；

效果展示 ：

2.倒计时实现

实现通过CountDownTimer实现，提供了start()和cancel() 两个方法，可以开始倒计时和取消倒计时，但是，(Android5.0以下)不可以停止，这是非常不给力的；

(1)解决方法1

在使用的时候，每次更新，将CountDownTimer 对象先调用cancel()方法，后进行销毁(赋值为null)，重新创建和初始化时间，并start();

(2)解决办法2

在网上查阅资料后，有人提供了android5.0的CountDownTimmer 源码，使用这个可以cancel(); 但是我没有成功；

源码分享：

/*

* Copyright (C) 2008 The Android Open Source Project

*

* Licensed under the Apache License, Version 2.0 (the "License");

* you may not use this file except in compliance with the License.

* You may obtain a copy of the License at

*

* http://www.apache.org/licenses/LICENSE-2.0

*

* Unless required by applicable law or agreed to in writing, software

* distributed under the License is distributed on an "AS IS" BASIS,

* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

* See the License for the specific language governing permissions and

* limitations under the License.

*/

package cn.labelnet.ui;

import android.os.Handler;

import android.os.Message;

import android.os.SystemClock;

/**

* Schedule a countdown until a time in the future, with regular notifications

* on intervals along the way.

*

* Example of showing a 30 second countdown in a text field:

*

* * new CountdownTimer(30000, 1000) {

*

* public void onTick(long millisUntilFinished) {

* mTextField.setText("seconds remaining: " + millisUntilFinished / 1000);

* }

*

* public void onFinish() {

* mTextField.setText("done!");

* }

* }.start();

*

*

* The calls to {@link #onTick(long)} are synchronized to this object so that

* one call to {@link #onTick(long)} won't ever occur before the previous

* callback is complete. This is only relevant when the implementation of

* {@link #onTick(long)} takes an amount of time to execute that is significant

* compared to the countdown interval.

*/

public abstract class CountDownTimer {

/**

* Millis since epoch when alarm should stop.

*/

private final long mMillisInFuture;

/**

* The interval in millis that the user receives callbacks

*/

private final long mCountdownInterval;

private long mStopTimeInFuture;

private boolean mCancelled = false;

/**

* @param millisInFuture

* The number of millis in the future from the call to

* {@link #start()} until the countdown is done and

* {@link #onFinish()} is called.

* @param countDownInterval

* The interval along the way to receive {@link #onTick(long)}

* callbacks.

*/

public CountDownTimer(long millisInFuture, long countDownInterval) {

mMillisInFuture = millisInFuture;

mCountdownInterval = countDownInterval;

}

/**

* Cancel the countdown.

*

* Do not call it from inside CountDownTimer threads

*/

public final void cancel() {

mHandler.removeMessages(MSG);

mCancelled = true;

}

/**

* Start the countdown.

*/

public synchronized final CountDownTimer start() {

if (mMillisInFuture <= 0) {

onFinish();

return this;

}

mStopTimeInFuture = SystemClock.elapsedRealtime() + mMillisInFuture;

mHandler.sendMessage(mHandler.obtainMessage(MSG));

mCancelled = false;

return this;

}

/**

* Callback fired on regular interval.

*

* @param millisUntilFinished

* The amount of time until finished.

*/

public abstract void onTick(long millisUntilFinished);

/**

* Callback fired when the time is up.

*/

public abstract void onFinish();

private static final int MSG = 1;

// handles counting down

private Handler mHandler = new Handler() {

@Override

public void handleMessage(Message msg) {

synchronized (CountDownTimer.this) {

final long millisLeft = mStopTimeInFuture

- SystemClock.elapsedRealtime();

if (millisLeft <= 0) {

onFinish();

} else if (millisLeft < mCountdownInterval) {

// no tick, just delay until done

sendMessageDelayed(obtainMessage(MSG), millisLeft);

} else {

long lastTickStart = SystemClock.elapsedRealtime();

onTick(millisLeft);

// take into account user's onTick taking time to execute

long delay = lastTickStart + mCountdownInterval

- SystemClock.elapsedRealtime();

// special case: user's onTick took more than interval to

// complete, skip to next interval

while (delay < 0)

delay += mCountdownInterval;

if (!mCancelled) {

sendMessageDelayed(obtainMessage(MSG), delay);

}

}

}

}

};

}

(3)倒计时实现

作用：

1)倒计时时间显示

2)进度条实时更新显示

3)歌词进度显示

4)播放结束 ：进度条设置为0，时间设置为总时长，回调LrcView播放结束，进行歌词初始化，显示第一行。

/**

* 倒计时

*/

private class CountDownTime extends CountDownTimer {

private double second = 0;

public CountDownTime(long millisInFuture, long countDownInterval) {

super(millisInFuture, countDownInterval);

}

@Override

public void onTick(long millisUntilFinished) {

//倒计时显示操作

second = millisUntilFinished / 1000;

tv_time_sheng.setText(TimeUtil.getMinuteBySecond((int) second));

// 进度条实现更新操作

second = (allSecond - second) / allSecond * 100;

//

progressbar_music.setProgress((int) second);

// 歌词更新操作

second = allSecond * 1000 - millisUntilFinished;

// Log.d("MaskMusic", "geci : "+(long)second);

lrc.updateTime((long) second);

// lrcplaytoend.playToPause((long)

// (allSecond*1000-millisUntilFinished));

}

@Override

public void onFinish() {

// showToast("MusicActivity 播放完毕");

lrc.destroyDrawingCache();

// 播放完毕显示歌词

// showLrc();

// 播放完毕需要进行 ，初始化界面 1.进度条初始值，2.歌词回归到第一行 3.时间恢复到总时间

// 播放中 ，暂停恢复 ： 1.进度条进度保持 2.歌词保持位置 3.时间保持(可以从MusicService获取)

progressbar_music.setProgress(0);

tv_time_sheng.setText(TimeUtil.getMinuteBySecond((int) allSecond));

allSecond = 0;

lrcplaytoend.playToEnd();

}

}

(4)一个单独的方法来初始化倒计时

private void CountDown(int allTime) {

countDown = new CountDownTime(allTime, COUNT_DOWN_INTERVAL);

}

(5)初始化倒计时所需要的判断

410001不需要看，里面的countDown是CountDownTimmer的对象，清楚该对象，重新重建倒计时，这是这里面使用的；

if (code == 41001) {

// 初始化 时间

if (countDown != null) {

countDown.cancel();

countDown = null;

}

CountDown(mm.getSeconds() * 1000);

} else {

// 销毁上一个对象

if (countDown != null) {

countDown.cancel();

countDown = null;

}

// 倒计时同步

currentTime = intent.getIntExtra(

MUSIC_SERVICE_TO_ACTIVITY_NOWTIME, 0);

CountDown(currentTime);

}

(6)将秒转化为分

/**

* 1.秒转分

*/

public static String getMinuteBySecond(int seconds) {

StringBuffer buffer = new StringBuffer();

int second = seconds % 60;

int minute = seconds / 60;

if (minute <= 9) {

buffer.append("0" + minute + ":");

} else {

buffer.append(minute + ":");

}

if (second <= 9) {

buffer.append("0" + second);

} else {

buffer.append(second);

}

return buffer.toString();

}

3.进度条实现

(1)布局实现

直接使用的是系统的ProgressBar , 不是很漂亮但很是可以使用的；

(2)控制实现

思路是倒计时在执行的时候，总时间减去当前的时间，后将时间换位百分制来使用，实时更新，如倒计时实现；

4.总结

倒计时和进度条的实现是相对简单的，主要是倒计时的实现，它决定了歌词显示，进度条显示，倒计时显示，三个主要的模块；在使用过程中遇到的问题就是上面的无法cancel() 。当然倒计时也可以自己去封装一个类使用，这里就不实现了。