# 1.背景 ? ? 還是音樂播放界面，實現倒計時和進度條功能，基本實現過程: 當打開MusicActivity 的時候，MusicService會發送廣播給MusicActivity ，后開始當前播放的時間進度，從而實現倒計時和進度條； ? ? 這里說明下 進度條是 從小到大 ，倒計時是 從大到小 ； ? ? 效果展示 ： ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? # 2.倒計時實現 ? ? ? 實現通過CountDownTimer實現，提供了start()和cancel() 兩個方法，可以開始倒計時和取消倒計時，但是，（Android5.0以下）不可以停止，這是非常不給力的； ### ? ? ?（1）解決方法1 ? ? ? ? ? ? ? 在使用的時候，每次更新，將CountDownTimer 對象先調用cancel()方法，后進行銷毀（賦值為null），重新創建和初始化時間，并start(); ### ? ? ?（2）解決辦法2 ? ? ? ? ? ? ? 在網上查閱資料后，有人提供了android5.0的CountDownTimmer 源碼，使用這個可以cancel(); 但是我沒有成功； ? ? ? ? 源碼分享： ~~~ /* * 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 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）倒計時實現 ? ? ? ? ? ? ? ?作用： ? ? ? ? ? ? ? ? ? ? ? ? 1）倒計時時間顯示 ? ? ? ? ? ? ? ? ? ? ? ? 2）進度條實時更新顯示 ? ? ? ? ? ? ? ? ? ? ? ? 3）歌詞進度顯示 ? ? ? ? ? ? ? ? ? ? ? ? 4）播放結束 ：進度條設置為0，時間設置為總時長，回調LrcView播放結束，進行歌詞初始化，顯示第一行。 ~~~ /** * 倒計時 */ private class CountDownTime extends CountDownTimer { private double second = 0; public CountDownTime(long millisInFuture, long countDownInterval) { super(millisInFuture, countDownInterval); } @Override public void onTick(long millisUntilFinished) { //倒計時顯示操作 second = millisUntilFinished / 1000; tv_time_sheng.setText(TimeUtil.getMinuteBySecond((int) second)); // 進度條實現更新操作 second = (allSecond - second) / allSecond * 100; // progressbar_music.setProgress((int) second); // 歌詞更新操作 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 播放完畢"); lrc.destroyDrawingCache(); // 播放完畢顯示歌詞 // showLrc(); // 播放完畢需要進行 ，初始化界面 1.進度條初始值，2.歌詞回歸到第一行 3.時間恢復到總時間 // 播放中 ，暫停恢復 ： 1.進度條進度保持 2.歌詞保持位置 3.時間保持（可以從MusicService獲取） progressbar_music.setProgress(0); tv_time_sheng.setText(TimeUtil.getMinuteBySecond((int) allSecond)); allSecond = 0; lrcplaytoend.playToEnd(); } } ~~~ ### ? ? ? ?（4）一個單獨的方法來初始化倒計時 ~~~ private void CountDown(int allTime) { countDown = new CountDownTime(allTime, COUNT_DOWN_INTERVAL); } ~~~ ### ? ? ? （5）初始化倒計時所需要的判斷 ? ? ? ? ? ? ? ? ?410001不需要看，里面的countDown是CountDownTimmer的對象，清楚該對象，重新重建倒計時，這是這里面使用的； ~~~ if (code == 41001) { // 初始化 時間 if (countDown != null) { countDown.cancel(); countDown = null; } CountDown(mm.getSeconds() * 1000); } else { // 銷毀上一個對象 if (countDown != null) { countDown.cancel(); countDown = null; } // 倒計時同步 currentTime = intent.getIntExtra( MUSIC_SERVICE_TO_ACTIVITY_NOWTIME, 0); CountDown(currentTime); } ~~~ ### ? ? ? ? ?（6）將秒轉化為分 ~~~ /** * 1.秒轉分 */ 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.進度條實現 ### ? ?（1）布局實現 ? ? ? ? ? ? ?直接使用的是系統的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）控制實現 ? ? ? ? ? ? ?思路是倒計時在執行的時候，總時間減去當前的時間，后將時間換位百分制來使用，實時更新，如倒計時實現； # 4.總結 ? ?倒計時和進度條的實現是相對簡單的，主要是倒計時的實現，它決定了歌詞顯示，進度條顯示，倒計時顯示，三個主要的模塊；在使用過程中遇到的問題就是上面的無法cancel() 。當然倒計時也可以自己去封裝一個類使用，這里就不實現了。