app下载链接，欢迎给我的所谓的app找bug，谢谢指教！听朋友反映，问题还不少，有的手机根本无法打开app,有的出现歌曲列表就闪退，正在努力debug,见谅，浪费各位流量了！ http://pan.baidu.com/s/1jHNa5Bg
前言
MusicBox的制作过程涉及到不少知识，如四大组件、MediaStore等等。制作完成后收获颇丰，现在带大家制作自己的音乐播放器。 #开发思路 程序由一个Activity（交互）和Service（后台播放音乐）构成。当发生单击事件时，Activity发送广播通知Service改变播放状态；Service将当前播放状态和当前播放的是哪一首歌曲广播给Activity供其更新UI界面。而歌曲信息（歌名、艺术家、路径等）则由系统的多媒体ContentProvider提供。
开发细节
1.布局界面有两个TextView及5个ImageButton（分别代表上一首、播放/暂停、下一首、停止、显示歌曲列表）.见文末效果展示图.5个Button均注册监听器，当单击事件发生时向Service发送广播。为了让Service知道哪个按钮被按下了，可以这样操作：
intent.putExra("contral",xxx); //xxx是Button的flag，比如
//“上一首”这个Button的flag设置为0x123
sendBrocast(intent);
2.Activity创建三个String数组,分别存储歌曲的title，artist，display_name,而Service中则创建一个String数组，用于存储歌曲的path。可以做到4个数组的同一下标对应同一首歌曲。这样做的好处是Activity和Service之间只需要交换数组的下标就可以实现TextView的更新以及歌曲的切换，避免了直接传输字符串。
3.Service设置一个status标志播放状态，并广播给Activity。Activity依据此改变表示播放/暂停的那个ImageButton显示的图片。
4.当用户点击用于显示歌曲列表的Button时，可以使用AlertDialog加载一个单选列表对话框，这相比跳转到另一Activity的思路更加简单易行。要使用户点击列表的某一首歌时能切歌并使列表消失，只需覆写 DialogInterface.OnClickListener的onClick方法即可，如下：
DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
Intent intent=new Intent(actionByActivity);//actionByActivity是自定义的action
intent.putExtra("contral",which);//which从0开始，表示第which+1首歌被点击
sendBroadcast(intent);
dialog.dismiss();//使dialog消失
}
}
5.Service使用MediaPlayer播放音乐，为了使在无用户交互时能顺序播放，为MediaPlayer对象注册播放完毕监听器，如下：
//player为MediaPlayer对象
player.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
@Override
public void onCompletion(MediaPlayer mp) {
player.reset();
try {
current=(current+1)%(num-1);//current是正在播放的歌曲的数组下标
player.setDataSource(path[current]);//path[]为路径数组
player.prepare();
player.start();
}catch (IOException e){
e.printStackTrace();
}
Intent intent=new Intent(MainActivity.actionByService);
intent.putExtra("current",current);
sendBroadcast(intent);//把current广播给Activity
}
});
重点知识讲解
MediaStore获取歌曲信息
类MediaStore可以看作是安卓Media数据库的配置说明（说明该数据库表名、列名、访问的uri等等），MediaStore这个类里面包含了Image、Audio、Video这几个内部类。其中类Audio中有以下表名：Media、Genres、Playlists、Artists、Albums，每一个表都有其供外部访问的uri和许多String类型的列名。顾名思义，要找专辑信息应当在Albums表找，其他类似。为了有个直观印象，看一下Media表的源码：
我们看到AudioColums继承了MediaColums,后者有title、display_name等列名，如图：
必备知识
1.AlertDialog创建对话框知识
2.SQLite数据库知识以及通过Cursor对象访问的知识
掌握了以上内容看起源码才能不费力气，鉴于篇幅限制，读者自行补充
源码
MainActivity.java
-------------------------------------------------------------------------------------
package com.golfer.www.musicboxdemo;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.support.v7.app.AppCompatActivity;
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.ContentResolver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.database.Cursor;
import android.media.MediaScannerConnection;
import android.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageButton;
import android.widget.RelativeLayout;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
//最大歌曲数目
final static int max_num=500;
//实际歌曲数目
int real_num=0;
//存储歌曲信息的数组
private String[] Artist=new String[max_num];
private String[] songname=new String[max_num];
private String[] display_name=new String[max_num];
//当前播放的歌曲的下标
int current=0;
//用于注册BrocastReceiver的action
/**
在Activity注册BrocastReceiver用到actionByService
在Service注册BrocastReceiver用到actionByActivity，完全可以将actionByActivity在myService.java里面定义
**/
static final String actionByActivity="MusicBoxDemo.action.actionByActivity";
static final String actionByService="MusicBoxDemo.action.actionByService";
//控件
TextView nameOfsong,artist;
ImageButton stop,playOrpause,previous,next,menu;
//BrocastReceiver
ActivityReceiver receiver;
//Intent
Intent intent;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//匹配控件
nameOfsong=(TextView)findViewById(R.id.nameOfsong) ;
artist=(TextView)findViewById(R.id.artist) ;
previous=(ImageButton)findViewById(R.id.previous);
playOrpause=(ImageButton)findViewById(R.id.playOrpause);
stop=(ImageButton)findViewById(R.id.stop) ;
next=(ImageButton)findViewById(R.id.next) ;
menu=(ImageButton)findViewById(R.id.menu) ;
//为按钮注册监听器
previous.setOnClickListener(this);
playOrpause.setOnClickListener(this);
stop.setOnClickListener(this);
next.setOnClickListener(this);
menu.setOnClickListener(this);
//读取MediaDataBase的信息（为数组赋值）
prepareInformation();
//注册BrocastReceiver
IntentFilter filter=new IntentFilter();
filter.addAction(actionByService);
receiver=new ActivityReceiver();
registerReceiver(receiver,filter);
//启动Service
this.intent=new Intent(MainActivity.this,myService.class);
startService(intent);
}
@Override
protected void onDestroy() {
//取消对BrocastReceiver的注册
unregisterReceiver(receiver);
//停止myService
stopService(this.intent);
super.onDestroy();
return;
}
//自定义BrocastReceiver,用于处理Service发过来的广播
private class ActivityReceiver extends BroadcastReceiver{
@Override
//覆写onReceive
public void onReceive(Context context, Intent intent) {
//update获取当前MediaPlayer的播放状态
int update=intent.getIntExtra("update",-1);
//current获取当前播放歌曲
int current=intent.getIntExtra("current",-1);
//更新文本框内容
if(current>=0){
nameOfsong.setText(songname[current]);
artist.setText(Artist[current]);
}
//更新按钮背景
switch(update){
case 0x11:
playOrpause.setImageResource(android.R.drawable.ic_media_pause);
break;
case 0x12:
playOrpause.setImageResource(android.R.drawable.ic_media_play);
break;
case 0x13:
playOrpause.setImageResource(android.R.drawable.ic_media_pause);
break;
}
}
}
//覆写onClick
public void onClick(View source){
final Intent intent=new Intent(actionByActivity);
//根据source的ID为intent的Extra属性赋不同的值
switch(source.getId()){
case R.id.previous:
intent.putExtra("contral",0x124);
break;
case R.id.playOrpause:
intent.putExtra("contral",0x125);
break;
case R.id.stop:
intent.putExtra("contral",0x126);
break;
case R.id.next:
intent.putExtra("contral",0x127);
break;
case R.id.menu:
//加载单选列表对话框
final AlertDialog dialog=new AlertDialog.Builder(MainActivity.this).setTitle("歌曲列表").setSingleChoiceItems(display_name, -1,
new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
Intent intent=new Intent(actionByActivity);
intent.putExtra("contral",which);
sendBroadcast(intent);
System.out.println("which:"+which);
dialog.dismiss();
}
}).create();
dialog.show();
}
sendBroadcast(intent);
}
//读取歌曲信息
private void prepareInformation(){
//创建ContentResolver
ContentResolver resolver=getContentResolver();
//读取艺术家信息
Cursor cursor= resolver.query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,null,null,null,null );
int index=0;
while(cursor.moveToNext()){
Artist[index++]=cursor.getString(cursor.getColumnIndex(MediaStore.Audio.AudioColumns.ARTIST));
}
real_num=index;
index=0;
//读取歌曲名
Cursor cursor2= resolver.query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,null,null,null,null );
while(cursor2.moveToNext()){
songname[index++]=cursor2.getString(cursor2.getColumnIndex(MediaStore.MediaColumns.TITLE));
}
index=0;
//读取歌曲的展示名
Cursor cursor3= resolver.query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,null,null,null,null );
while(cursor3.moveToNext()){
display_name[index++]=cursor3.getString(cursor3.getColumnIndex(MediaStore.MediaColumns.TITLE));
}
}
}
------------------------------------------------------------------------------------------
myService.java
package com.golfer.www.musicboxdemo;
import android.app.Service;
import android.content.BroadcastReceiver;
import android.content.ContentResolver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.database.Cursor;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.net.Uri;
import android.os.IBinder;
import android.provider.MediaStore;
import android.support.annotation.Nullable;
import android.support.annotation.StringDef;
import java.io.IOException;
/**
* Created by Golfer on 2017/2/4.
*/
public class myService extends Service {
String[] path=new String[MainActivity.max_num];
MediaPlayer player;
int current=0;
int status=0x11;
int num;
ServiceReceiver receiver;
public void onCreate() {
System.out.println("---Service已启动---");
IntentFilter filter=new IntentFilter();
filter.addAction(MainActivity.actionByActivity);
receiver=new ServiceReceiver();
registerReceiver(receiver,filter);
if((player=new MediaPlayer())!=null) System.out.println("---MediaPlayer创建成功---");
else System.out.println("---MediaPlayer创建失败---");
player.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
@Override
public void onCompletion(MediaPlayer mp) {
player.reset();
try {
current=(current+1)%(num-1);
player.setDataSource(path[current]);
player.prepare();
player.start();
}catch (IOException e){
e.printStackTrace();
}
Intent intent=new Intent(MainActivity.actionByService);
intent.putExtra("current",current);
sendBroadcast(intent);
}
});
ContentResolver resolver=getContentResolver();
Cursor cursor= resolver.query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,null,null,null,null );
int index=0;
while(cursor.moveToNext()){
path[index]=cursor.getString(cursor.getColumnIndex(MediaStore.MediaColumns.DATA));
System.out.println("path["+index+"]:"+path[index]);
index++;
}
num=index;
return;
}
public IBinder onBind(Intent intent) {
return null;
}
@Override
public void onDestroy() {
unregisterReceiver(receiver);
player.release();
super.onDestroy();
return;
}
private class ServiceReceiver extends BroadcastReceiver{
@Override
public void onReceive(Context context, Intent intent) {
int contral=intent.getIntExtra("contral",-1);
if(contral>=0) {
switch (contral) {
case 0x124:
if (status == 0x12 && current > 0) {
player.reset();
try {
player.setDataSource(path[current - 1]);
player.prepare();
player.start();
System.out.println("---成功播放上一首歌曲---");
current = current - 1;
} catch (IOException E) {
E.printStackTrace();
}
}
break;
case 0x125:
if (status == 0x11) {
try {
player.reset();
player.setDataSource(path[current]);
player.prepare();
player.start();
status = 0x12;
} catch (IOException e) {
e.printStackTrace();
}
} else if (status == 0x12) {
player.pause();
status = 0x13;
} else if (status == 0x13) {
player.start();
status = 0x12;
}
break;
case 0x126:
if (status == 0x12 || status == 0x13) {
player.stop();
status = 0x11;
}
break;
case 0x127:
if (status == 0x12 && current < num - 1) {
player.reset();
try {
player.setDataSource(path[current + 1]);
player.prepare();
player.start();
System.out.println("---成功播放下一首歌曲---");
current = current + 1;
} catch (IOException E) {
E.printStackTrace();
}
}
break;
default:
player.reset();
try {
player.setDataSource(path[contral]);
player.prepare();
player.start();
current=contral;
System.out.println("---成功切换播放第"+(current+1)+"首歌---");
}catch (IOException e){
e.printStackTrace();
}
}
}
Intent intent1=new Intent(MainActivity.actionByService);
intent1.putExtra("update",status);
intent1.putExtra("current",current);
sendBroadcast(intent1);
}
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.golfer.www.musicboxdemo.MainActivity">
<TextView
android:text="歌曲名称"
android:layout_height="wrap_content"
android:id="@+id/nameOfsong"
android:layout_alignParentStart="true"
android:layout_width="wrap_content"
android:textAppearance="@style/TextAppearance.AppCompat.Small" />
<ImageButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:srcCompat="@android:drawable/ic_media_next"
android:layout_alignTop="@+id/previous"
android:layout_alignParentEnd="true"
android:id="@+id/next" />
<ImageButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:srcCompat="@android:drawable/ic_media_previous"
android:layout_marginBottom="132dp"
android:id="@+id/previous"
android:layout_alignParentBottom="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
<ImageButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:srcCompat="@android:drawable/ic_media_pause"
android:id="@+id/playOrpause"
android:layout_alignTop="@+id/next"
android:layout_centerHorizontal="true" />
<ImageButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:srcCompat="@android:drawable/ic_lock_power_off"
android:id="@+id/stop"
android:layout_marginTop="29dp"
android:layout_below="@+id/playOrpause"
android:layout_toRightOf="@+id/previous"
android:layout_toEndOf="@+id/previous" />
<TextView
android:text="歌手"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/artist"
android:textAppearance="@style/TextAppearance.AppCompat.Small"
android:layout_marginTop="44dp"
android:layout_below="@+id/nameOfsong"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
<ImageButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:srcCompat="@android:drawable/ic_menu_sort_by_size"
android:layout_alignBottom="@+id/stop"
android:layout_toLeftOf="@+id/next"
android:layout_toStartOf="@+id/next"
android:layout_marginRight="11dp"
android:layout_marginEnd="11dp"
android:id="@+id/menu" />
</RelativeLayout>
-------------------------------------------------------------------------------------------------
AndroidManifest.xml //记得要在此文件中注册myService,
//并且为程序添加访问外部存储器的权限，由于两个BrocastReceiver均使用动态注册方式，
//故无须在此文件注册
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.golfer.www.musicboxdemo">
<application
android:allowBackup="true"
android:icon="mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme">
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service android:name=".myService">
</service>
</application>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
</manifest>
效果展示
由于知识水平限制，app难免存在各种bug，请各位指教，或者有其他好的开发思路，欢迎共同交流！ app下载链接，欢迎给我的所谓的app找bug，谢谢指教！ http://pan.baidu.com/s/1jHNa5Bg