Android 音乐播放器的实现（二）界面的实现
浏览数：19 /
时间：2015年06月11日
写程序的过程中，想法总会不断地变，有时候会很纠结，到底做哪种效果好，怎么做好呢？
就比如这个音乐播放器，我原来的想法是把列表页面跟歌词页面放在同一个Activity中的两个Fragment，然后通过左右滑动来进行页面的切换。
但是看了酷狗的播放器，它是在启动页面点击了左下角的按钮，就会把歌词页面从右下角斜切上来，我觉得也挺帅的呀，又想做这个效果了。
不管怎么样，先做出一个来再说吧。
下面先看一下效果动态图，是用4.4的AVD来播放的，因为那个斜切上来的动画，会用到一些属性是3.0才支持的，所以2.3的机器做不出来。机器有点差，开个模拟器真是慢到死。
做得比较匆忙，其实还是有不少Bug的，还有一些功能，比如歌词也还没实现，请各位多包涵。
效果图：
下面我们分几步来讲：
界面：
目前只有两个界面，列表界面MainActivity和歌词DetailActivity。
列表界面也分两部分，上面是一个ListView,下面是一个RelativeLayout，里面放了一个按钮（去歌词界面），一个进度条，一个TextView去显示歌名，两个控制按钮，播放和前进（酷狗就是只有这两个按钮，有点好奇设计的理念是什么，为什么不加前一首？），这个看布局的xml就一目了然了。
\res\layout\activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity" >
<ListView
android:id="@+id/lvSongs"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="8"
android:cacheColorHint="#00000000" />
<RelativeLayout
android:layout_width="match_parent"
android:background="#BBBBBB"
android:layout_height="0dp"
android:layout_weight="1" >
<Button
android:id="@+id/btnDetail"
android:layout_width="48dip"
android:layout_height="48dip"
android:layout_margin="0dip"
android:background="@drawable/music_app"
android:layout_alignParentBottom="true"
android:layout_alignParentTop="true"/>
<SeekBar
android:id="@+id/pbDuration"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="wrap_content"
android:layout_marginTop="3dip"
android:layout_height="10dip"
android:layout_marginBottom="3dip"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:layout_toRightOf="@+id/btnDetail"
android:maxHeight="1dip"
android:minHeight="1dip"
android:progressDrawable="@drawable/progress_style"
android:thumbOffset="0dip"
android:thumb="@drawable/seekbar_thumb"/>
<TextView
android:id="@+id/tvCurrentMusic"
android:layout_width="190dp"
android:layout_height="32dip"
android:layout_alignBaseline="@+id/btnNext"
android:layout_toRightOf="@+id/btnDetail"
android:gravity="left|center_vertical"
android:paddingLeft="5dip"
android:paddingRight="5dip" />
<Button
android:id="@+id/btnStartStop"
android:layout_width="32dip"
android:layout_height="32dip"
android:layout_alignBaseline="@+id/btnNext"
android:layout_below="@+id/pbDuration"
android:layout_toLeftOf="@+id/btnNext"
android:background="@drawable/play"
android:layout_marginRight="5dip"
/>
<Button
android:id="@+id/btnNext"
android:layout_width="24dp"
android:layout_height="24dp"
android:layout_alignParentRight="true"
android:layout_below="@+id/pbDuration"
android:layout_marginRight="20dip"
android:background="@drawable/forward" />
</RelativeLayout>
</LinearLayout>其中进度条是用自定义的风格的（也是在CSDN上找的，还没去具体了解，到时了解了再讲一下）。下面是DetailActivity的布局xml.
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:custom="http://schemas.android.com/apk/res/com.example.nature"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/tvTitle"
android:layout_width="match_parent"
android:layout_height="0dip"
android:layout_weight="1"
android:background="#00EEEE"
android:gravity="center_vertical"
android:paddingLeft="5dip"
android:paddingRight="5dip" />
<TextView
android:id="@+id/tvLyric"
android:layout_width="match_parent"
android:layout_height="0dip"
android:layout_weight="9"
android:gravity="center_vertical"
android:text="To Continue...." />
<LinearLayout
android:id="@+id/llProgress"
android:layout_width="match_parent"
android:layout_height="0dip"
android:layout_weight="1"
android:gravity="center_horizontal"
android:orientation="horizontal" >
<TextView
android:id="@+id/tvTimeElapsed"
android:layout_width="0dip"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal|center_vertical"
android:layout_weight="1"
android:text="00:00" />
<SeekBar
android:id="@+id/pbDuration"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="0dip"
android:layout_height="10dip"
android:layout_gravity="center_horizontal|center_vertical"
android:layout_weight="6"
android:maxHeight="1dip"
android:minHeight="1dip"
android:progressDrawable="@drawable/progress_style"
android:secondaryProgress="0"
android:thumb="@drawable/seekbar_thumb"
android:thumbOffset="0dip" />
<TextView
android:id="@+id/tvDuration"
android:layout_width="0dip"
android:layout_height="wrap_content"
android:layout_gravity="center_horizontal|center_vertical"
android:layout_weight="1"
android:text="00:00" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="0dip"
android:layout_weight="2"
android:orientation="horizontal" >
<com.example.nature.CustomAudioIcon
android:id="@+id/btnMode"
android:layout_width="0dip"
android:layout_height="match_parent"
android:layout_weight="1"
custom:type="mode"
custom:color="#66DD22" />
<com.example.nature.CustomAudioIcon
android:id="@+id/btnPrevious"
android:layout_width="0dip"
android:layout_height="match_parent"
android:layout_weight="1"
custom:type="backward"
custom:color="#66DD22" />
<com.example.nature.CustomAudioIcon
android:id="@+id/btnStartStop"
android:layout_width="0dip"
android:layout_height="match_parent"
android:layout_weight="1"
custom:type="start"
custom:color="#66DD22" />
<com.example.nature.CustomAudioIcon
android:id="@+id/btnNext"
android:layout_width="0dip"
android:layout_height="match_parent"
android:layout_weight="1"
custom:type="forward"
custom:color="#66DD22" />
<com.example.nature.CustomAudioIcon
android:id="@+id/btnExit"
android:layout_width="0dip"
android:layout_height="match_parent"
android:layout_weight="1"
custom:type="exit"
custom:color="#66DD22" />
</LinearLayout>
</LinearLayout>这里面有三部分：上端的是一个TextView，用来显示歌曲名的。
中间的是一个歌词显示，目前还没实现，所以显示了“To Continue...”。
最下面是五个自定义按钮（上网找图标真是很麻烦的，自定义按钮的实现，请看前一篇博文
控制逻辑
说完界面，下面就是来说我们控制逻辑。
下面是Activity的代码，先贴上来，我再仔细说一下实现。
public class MainActivity extends Activity implements OnClickListener{
public static final String TAG = "com.example.nature.MAIN_ACTIVITY";
private ListView lvSongs;
private SeekBar pbDuration;
private TextView tvCurrentMusic;
private List<MusicInfo> musicList;
private int currentMusic; // The music that is playing.
private int currentPosition; //The position of the music is playing.
private int currentMax;
private Button btnStartStop;
private Button btnNext;
private Button btnDetail;
private ProgressReceiver progressReceiver;
private NatureBinder natureBinder;
private ServiceConnection serviceConnection = new ServiceConnection() {
@Override
public void onServiceDisconnected(ComponentName name) {
}
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
natureBinder = (NatureBinder) service;
}
};
private void connectToNatureService(){
Intent intent = new Intent(MainActivity.this, NatureService.class);
bindService(intent, serviceConnection, BIND_AUTO_CREATE);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
Log.v(TAG, "OnCreate");
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
MusicLoader musicLoader = MusicLoader.instance(getContentResolver());
musicList = musicLoader.getMusicList();
connectToNatureService();
initComponents();
}
public void onResume(){
Log.v(TAG, "OnResume register Progress Receiver");
super.onResume();
registerReceiver();
if(natureBinder != null){
if(natureBinder.isPlaying()){
btnStartStop.setBackgroundResource(R.drawable.pause);
}else{
btnStartStop.setBackgroundResource(R.drawable.play);
}
natureBinder.notifyActivity();
}
}
public void onPause(){
Log.v(TAG, "OnPause unregister Progress Receiver");
super.onPause();
unregisterReceiver(progressReceiver);
}
public void onStop(){
Log.v(TAG, "OnStop");
super.onStop();
}
public void onDestroy(){
Log.v(TAG, "OnDestroy");
super.onDestroy();
if(natureBinder != null){
unbindService(serviceConnection);
}
}
private void initComponents(){
pbDuration = (SeekBar) findViewById(R.id.pbDuration);
pbDuration.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {
@Override
public void onStopTrackingTouch(SeekBar seekBar) {}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {}
@Override
public void onProgressChanged(SeekBar seekBar, int progress,
boolean fromUser) {
if(fromUser){
natureBinder.changeProgress(progress);
}
}
});
tvCurrentMusic = (TextView) findViewById(R.id.tvCurrentMusic);
btnStartStop = (Button)findViewById(R.id.btnStartStop);
btnStartStop.setOnClickListener(this);
btnNext = (Button)findViewById(R.id.btnNext);
btnNext.setOnClickListener(this);
btnDetail = (Button) findViewById(R.id.btnDetail);
btnDetail.setOnClickListener(this);
MusicAdapter adapter = new MusicAdapter();
lvSongs = (ListView) findViewById(R.id.lvSongs);
lvSongs.setAdapter(adapter);
lvSongs.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
currentMusic = position;
natureBinder.startPlay(currentMusic,0);
if(natureBinder.isPlaying()){
btnStartStop.setBackgroundResource(R.drawable.pause);
}
}
});
}
private void registerReceiver(){
progressReceiver = new ProgressReceiver();
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(NatureService.ACTION_UPDATE_PROGRESS);
intentFilter.addAction(NatureService.ACTION_UPDATE_DURATION);
intentFilter.addAction(NatureService.ACTION_UPDATE_CURRENT_MUSIC);
registerReceiver(progressReceiver, intentFilter);
}
class MusicAdapter extends BaseAdapter{
@Override
public int getCount() {
return musicList.size();
}
@Override
public Object getItem(int position) {
return musicList.get(position);
}
@Override
public long getItemId(int position) {
return musicList.get(position).getId();
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder;
if(convertView == null){
convertView = LayoutInflater.from(MainActivity.this).inflate(R.layout.music_item, null);
ImageView pImageView = (ImageView) convertView.findViewById(R.id.albumPhoto);
TextView pTitle = (TextView) convertView.findViewById(R.id.title);
TextView pDuration = (TextView) convertView.findViewById(R.id.duration);
TextView pArtist = (TextView) convertView.findViewById(R.id.artist);
viewHolder = new ViewHolder(pImageView, pTitle, pDuration, pArtist);
convertView.setTag(viewHolder);
}else{
viewHolder = (ViewHolder) convertView.getTag();
}
viewHolder.imageView.setImageResource(R.drawable.audio);
viewHolder.title.setText(musicList.get(position).getTitle());
viewHolder.duration.setText(FormatHelper.formatDuration(musicList.get(position).getDuration()));
viewHolder.artist.setText(musicList.get(position).getArtist());
return convertView;
}
}
class ViewHolder{
public ViewHolder(ImageView pImageView, TextView pTitle, TextView pDuration, TextView pArtist){
imageView = pImageView;
title = pTitle;
duration = pDuration;
artist = pArtist;
}
ImageView imageView;
TextView title;
TextView duration;
TextView artist;
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btnStartStop:
play(currentMusic,R.id.btnStartStop);
break;
case R.id.btnNext:
natureBinder.toNext();
break;
case R.id.btnDetail:
Intent intent = new Intent(MainActivity.this,DetailActivity.class);
intent.putExtra(DetailActivity.MUSIC_LENGTH, currentMax);
intent.putExtra(DetailActivity.CURRENT_MUSIC, currentMusic);
intent.putExtra(DetailActivity.CURRENT_POSITION, currentPosition);
startActivity(intent);
break;
}
}
private void play(int position, int resId){
if(natureBinder.isPlaying()){
natureBinder.stopPlay();
btnStartStop.setBackgroundResource(R.drawable.play);
}else{
natureBinder.startPlay(position,currentPosition);
btnStartStop.setBackgroundResource(R.drawable.pause);
}
}
class ProgressReceiver extends BroadcastReceiver{
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if(NatureService.ACTION_UPDATE_PROGRESS.equals(action)){
int progress = intent.getIntExtra(NatureService.ACTION_UPDATE_PROGRESS, 0);
if(progress > 0){
currentPosition = progress; // Remember the current position
pbDuration.setProgress(progress / 1000);
}
}else if(NatureService.ACTION_UPDATE_CURRENT_MUSIC.equals(action)){
//Retrive the current music and get the title to show on top of the screen.
currentMusic = intent.getIntExtra(NatureService.ACTION_UPDATE_CURRENT_MUSIC, 0);
tvCurrentMusic.setText(musicList.get(currentMusic).getTitle());
}else if(NatureService.ACTION_UPDATE_DURATION.equals(action)){
//Receive the duration and show under the progress bar
//Why do this ? because from the ContentResolver, the duration is zero.
currentMax = intent.getIntExtra(NatureService.ACTION_UPDATE_DURATION, 0);
int max = currentMax / 1000;
Log.v(TAG, "[Main ProgressReciver] Receive duration : " + max);
pbDuration.setMax(currentMax / 1000);
}
}
}
}
接下来说说主要的实现逻辑：
1）加载歌曲，写了一个MusicLoader来读取本地sdcard中的歌曲，这一方面的请参考：
2）将歌曲放到ListView中，写了一个继承于BaseAdapter的MusicAdapter，一般实现BaseAdapter，都会用到下面两种优化方式：
2.1）重复利用ConvertView，保证同一个时刻在列表的View不会太多
2.3）利用ViewHolder，来存放加载过的View，不用每次都要重新用findViewById去实例化View，节省成本
3）绑定Service，音乐播放器主要的操作，包括播放，暂停，前进，后退等，都是在Service中实现的，我们在Service里面实现了一个Binder，在里面定义了几种操作，然后传给Activity，让Activity可以跟Service进行互动。
4）继承BroadcastReceiver 实现一个自定义的Receiver，接收从Service传过来的广播，比如当前播放的位置，播放的前/后一首是什么，播放的当前模式是什么，这些都要从Service传回到Activity中，从而让Activity可以根据这些状态去更新按钮的状态。
基本的功能就是这样。
在这里面有一点要注意的就是，注册广播的时候，最好是在OnResume中，因为在OnPause的时候我们会将这个广播给卸掉，这样从歌词界面切回来的时候，系统只会调用OnResume函数，从而就会重新将广播给注册上，而不需要让广播一直监听信息（即使Activity都没显示了）。
基本的逻辑大概就是这样了，但是这里面还是会有很多小细节需要完善的。
比如在Detail界面中一首歌播完了，开始播下一首，那么Service会传个广播回到这个Activity，告诉当前界面要更新歌曲名，歌曲长度，但是如果这个时候我们切回Main界面的话，
Service是不会知道要发送广播回Main界面告诉它要更新的（因为只有在一首歌结束的时候，进入下一首歌的时候才发广播）， 那么此时就要在MainActivity恢复（OnResume）的时候，让Service发送广播回来，所以可以在MainActivity中看到如下的代码：
public void onResume(){
Log.v(TAG, "OnResume register Progress Receiver");
super.onResume();
registerReceiver();
if(natureBinder != null){
...
natureBinder.notifyActivity();
}
}
在Service中的Binder也提供了这样一个接口，来让Activity告诉Service，我想知道当前在播哪一首歌。。。所以在Service中的Binder类，其实我们要实现比较多的接口来跟Activity中交互的，先列举一下，下一篇文章会详细说一下Service
class NatureBinder extends Binder{
public void startPlay(int currentMusic, int currentPosition){
play(currentMusic,currentPosition);
}
public void stopPlay(){
stop();
}
public void toNext(){
playNext();
}
public void toPrevious(){
playPrevious();
}
/**
* MODE_ONE_LOOP = 1;
* MODE_ALL_LOOP = 2;
* MODE_RANDOM = 3;
* MODE_SEQUENCE = 4;
*/
public void changeMode(){
currentMode = (currentMode + 1) % 4;
Log.v(TAG, "[NatureBinder] changeMode : " + currentMode);
Toast.makeText(NatureService.this, MODE_DESC[currentMode], Toast.LENGTH_SHORT).show();
}
/**
* return the current mode
* MODE_ONE_LOOP = 1;
* MODE_ALL_LOOP = 2;
* MODE_RANDOM = 3;
* MODE_SEQUENCE = 4;
* @return
*/
public int getCurrentMode(){
return currentMode;
}
/**
* The service is playing the music
* @return
*/
public boolean isPlaying(){
return isPlaying;
}
/**
* Notify Activities to update the current music and duration when current activity changes.
*/
public void notifyActivity(){
toUpdateCurrentMusic();
toUpdateDuration();
}
/**
* Seekbar changes
* @param progress
*/
public void changeProgress(int progress){
...
}
public class DetailActivity extends Activity implements OnClickListener{
private static final String TAG = "com.example.natrue.DetailActivity";
public static final String MUSIC_LENGTH = "com.example.nature.DetailActivity.MUSIC_LENGTH";
public static final String CURRENT_POSITION = "com.example.nature.DetailActivity.CURRENT_POSITION";
public static final String CURRENT_MUSIC = "com.example.nature.DetailActivity.CURRENT_MUSIC";
private SeekBar pbDuration;
private TextView tvTitle,tvTimeElapsed, tvDuration;
private List<MusicInfo> musicList;
private int currentMusic;
private int currentPosition;
private ProgressReceiver progressReceiver;
private NatureBinder natureBinder;
private int[] btnResIds = new int[] {
R.id.btnMode,
R.id.btnPrevious,
R.id.btnStartStop,
R.id.btnNext,
R.id.btnExit
};
private ServiceConnection serviceConnection = new ServiceConnection() {
@Override
public void onServiceDisconnected(ComponentName name) {
}
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
natureBinder = (NatureBinder) service;
if(natureBinder.isPlaying()){
CustomAudioIcon btnStartStop = (CustomAudioIcon)findViewById(R.id.btnStartStop);
btnStartStop.setFlagStart(false);
}
CustomAudioIcon btnMode = (CustomAudioIcon)findViewById(R.id.btnMode);
btnMode.setCurrentMode(natureBinder.getCurrentMode());
}
};
private void connectToNatureService(){
Intent intent = new Intent(DetailActivity.this, NatureService.class);
bindService(intent, serviceConnection, BIND_AUTO_CREATE);
}
@Override
public void onCreate(Bundle savedInstanceState){
Log.v(TAG, "OnCreate");
super.onCreate(savedInstanceState);
overridePendingTransition(R.anim.push_right_in,R.anim.hold);
MusicLoader musicLoader = MusicLoader.instance(getContentResolver());
musicList = musicLoader.getMusicList();
setContentView(R.layout.detail_layout);
connectToNatureService();
initComponents();
}
public void onResume(){
Log.v(TAG, "OnResume");
super.onResume();
initReceiver();
}
public void onPause(){
Log.v(TAG, "OnPause unregister progress receiver");
super.onPause();
unregisterReceiver(progressReceiver);
overridePendingTransition(R.anim.hold, R.anim.push_right_out);
}
public void onStop(){
Log.v(TAG, "OnStop");
super.onStop();
}
public void onDestroy(){
Log.v(TAG, "Destroy");
super.onDestroy();
if(natureBinder != null){
unbindService(serviceConnection);
}
}
private void initComponents(){
tvTitle = (TextView) findViewById(R.id.tvTitle);
currentMusic = getIntent().getIntExtra(CURRENT_MUSIC,0);
tvTitle.setText(musicList.get(currentMusic).getTitle());
tvDuration = (TextView) findViewById(R.id.tvDuration);
int max = getIntent().getIntExtra(MUSIC_LENGTH, 0);
tvDuration.setText(FormatHelper.formatDuration(max));
pbDuration = (SeekBar) findViewById(R.id.pbDuration);
pbDuration.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {
@Override
public void onStopTrackingTouch(SeekBar seekBar) {}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {}
@Override
public void onProgressChanged(SeekBar seekBar, int progress,
boolean fromUser) {
if(fromUser){
natureBinder.changeProgress(progress);
}
}
});
pbDuration.setMax(max/1000);
currentPosition = getIntent().getIntExtra(CURRENT_POSITION,0);
pbDuration.setProgress(currentPosition / 1000);
tvTimeElapsed = (TextView) findViewById(R.id.tvTimeElapsed);
tvTimeElapsed.setText(FormatHelper.formatDuration(currentPosition));
for(int resId : btnResIds){
CustomAudioIcon icon = (CustomAudioIcon)findViewById(resId);
icon.setOnClickListener(this);
}
}
private void initReceiver(){
progressReceiver = new ProgressReceiver();
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(NatureService.ACTION_UPDATE_PROGRESS);
intentFilter.addAction(NatureService.ACTION_UPDATE_DURATION);
intentFilter.addAction(NatureService.ACTION_UPDATE_CURRENT_MUSIC);
registerReceiver(progressReceiver, intentFilter);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btnStartStop:
play(currentMusic,R.id.btnStartStop);
break;
case R.id.btnNext:
natureBinder.toNext();
break;
case R.id.btnPrevious:
natureBinder.toPrevious();
break;
case R.id.btnExit:
finish();
break;
case R.id.btnMode:
natureBinder.changeMode();
break;
default:
break;
}
}
private void play(int currentMusic, int resId){
CustomAudioIcon btnStartStop = (CustomAudioIcon) findViewById(resId);
if(btnStartStop.isStartStatus()){
natureBinder.stopPlay();
}else{
natureBinder.startPlay(currentMusic,currentPosition);
}
}
class ProgressReceiver extends BroadcastReceiver{
@Override
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
if(NatureService.ACTION_UPDATE_PROGRESS.equals(action)){
int progress = intent.getIntExtra(NatureService.ACTION_UPDATE_PROGRESS, currentPosition);
if(progress > 0){
currentPosition = progress; // Remember the current position
tvTimeElapsed.setText(FormatHelper.formatDuration(progress));
pbDuration.setProgress(progress / 1000);
}
}else if(NatureService.ACTION_UPDATE_CURRENT_MUSIC.equals(action)){
//Retrieve the current music and get the title to show on top of the screen.
currentMusic = intent.getIntExtra(NatureService.ACTION_UPDATE_CURRENT_MUSIC, 0);
tvTitle.setText(musicList.get(currentMusic).getTitle());
}else if(NatureService.ACTION_UPDATE_DURATION.equals(action)){
//Receive the duration and show under the progress bar
//Why do this ? because from the ContentResolver, the duration is zero.
int duration = intent.getIntExtra(NatureService.ACTION_UPDATE_DURATION, 0);
tvDuration.setText(FormatHelper.formatDuration(duration));
pbDuration.setMax(duration / 1000);
}
}
}实现的功能也是类似的，不过为了实现动画效果斜切入的一个功能，我们可以看到在OnCreate函数和OnPause函数中，分别有如下两行代码： @Override
public void onCreate(Bundle savedInstanceState){
...
overridePendingTransition(R.anim.push_right_in,R.anim.hold);
...
}
@Override
public void onPause(){
...
overridePendingTransition(R.anim.hold, R.anim.push_right_out)
;
}这就是为了实现动画斜切效果的一个函数，进入当前Activity的效果是要在OnCreate的SetContentView之前，也就是在添加View到窗口展示前要把这个效果设置进去，而离开当前的Activity的效果要在OnPause的时候，也就是OnStop之前，在界面不见之前把效果给设置进去。
这个函数有两个参数，其中第一个参数是进入下一个Activity的动画，后一个参数是离开当前Activity的动画。
public void overridePendingTransition(int enterAnim, int exitAnim) {
try {
ActivityManagerNative.getDefault().overridePendingTransition(
mToken, getPackageName(), enterAnim, exitAnim);
} catch (RemoteException e) {
}
}我们再来看一下动画效果的设置，是利用xml来设置的，
res/anim/push_right_in.xml
<set xmlns:android="http://schemas.android.com/apk/res/android"> <translate android:fromYDelta="100%p" android:toYDelta="0" android:fromXDelta="100%p" android:toXDelta="0" android:duration="500"/> <rotate android:fromDegrees="90" android:toDegrees="0" android:pivotX="100%p" android:pivotY="100%p" android:duration="500"/> <alpha android:fromAlpha="0.0" android:toAlpha="1.0" android:duration="500" /> </set>
res/anim/push_right_out.xml
<set xmlns:android="http://schemas.android.com/apk/res/android"> <translate android:fromXDelta="0" android:toXDelta="100%p" android:fromYDelta="0" android:toYDelta="100%p" android:duration="500"/> <rotate android:fromDegrees="0" android:toDegrees="90" android:pivotX="100%p" android:pivotY="100%p" android:duration="500"/> <alpha android:fromAlpha="1.0" android:toAlpha="0.0" android:duration="500" /> </set>
res/anim/hold.xml
<set xmlns:android="http://schemas.android.com/apk/res/android"> <translate android:fromXDelta="0" android:toXDelta="0" android:duration="500"/> </set>
其中push_right_in 和 push_right_out实现的是相反的效果，一个是从右边斜切进来，一个是斜切出去，而hold是为了保证MainActivity不动的。
而rotate效果中的，pivotX和pivotY是3.0之后才支持的，所以在2.X中的没办法实现这个效果的。
关于界面显示的大概就是这么多了，有一些逻辑是跟Service相关的，下一篇讲Service的实现的时候再提一些。
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