Android实战 - 音心播放器 （MusicActivity - 倒计时 ，进度条实现）

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: * * <pre class="prettyprint"> * new CountdownTimer(30000, 1000) { *  * public void onTick(long millisUntilFinished) { * mTextField.setText("seconds remaining: " + millisUntilFinished / 1000); * } *  * public void onFinish() { * mTextField.setText("done!"); * } * }.start(); * </pre> * * 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 downprivate Handler mHandler = new Handler() {@Overridepublic 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 donesendMessageDelayed(obtainMessage(MSG), millisLeft);} else {long lastTickStart = SystemClock.elapsedRealtime();onTick(millisLeft);// take into account user's onTick taking time to executelong delay = lastTickStart + mCountdownInterval- SystemClock.elapsedRealtime();// special case: user's onTick took more than interval to// complete, skip to next intervalwhile (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);}@Overridepublic 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));}@Overridepublic 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；

    <ProgressBar                    android:id="@+id/progressbar_music"                    style="?android:attr/progressBarStyleHorizontal"                    android:layout_width="match_parent"                    android:layout_height="wrap_content"                    android:layout_below="@+id/tv_time_sheng"                    android:layout_centerInParent="true"                    android:max="100"                    android:progress="50" />

    （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。