Android Studio 入门：（四） 音乐播放器的实现
一、实现效果
点击“上一首”键、“下一首”键可切换歌曲，点击“暂停”键可暂停歌曲。
二、涉及到的知识点
1.ContentResolver
2.RecyclerView.Adapter
3.MediaPlayer
三、编码实现
//MainAcitivity.java
package com.animee.localmusic;
import android.content.ContentResolver;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.media.MediaPlayer;
import android.net.Uri;
import android.provider.MediaStore;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
ImageView nextIv,playIv,lastIv,albumIv;
TextView singerTv,songTv;
RecyclerView musicRv;
// 数据源
ListmDatas;
private LocalMusicAdapter adapter;
// 记录当前正在播放的音乐的位置
int currnetPlayPosition = -1;
// 记录暂停音乐时进度条的位置
int currentPausePositionInSong = 0;
MediaPlayer mediaPlayer;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
mediaPlayer = new MediaPlayer();
mDatas = new ArrayList<>();
// 创建适配器对象
adapter = new LocalMusicAdapter(this, mDatas);
musicRv.setAdapter(adapter);
// 设置布局管理器
LinearLayoutManager layoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);
musicRv.setLayoutManager(layoutManager);
// 加载本地数据源
loadLocalMusicData();
// 设置每一项的点击事件
setEventListener();
}
private void setEventListener() {
/* 设置每一项的点击事件*/
adapter.setOnItemClickListener(new LocalMusicAdapter.OnItemClickListener() {
@Override
public void OnItemClick(View view, int position) {
currnetPlayPosition = position;
LocalMusicBean musicBean = mDatas.get(position);
playMusicInMusicBean(musicBean);
}
});
}
public void playMusicInMusicBean(LocalMusicBean musicBean) {
/*根据传入对象播放音乐*/
//设置底部显示的歌手名称和歌曲名
singerTv.setText(musicBean.getSinger());
songTv.setText(musicBean.getSong());
stopMusic();
// 重置多媒体播放器
mediaPlayer.reset();
// 设置新的播放路径
try {
mediaPlayer.setDataSource(musicBean.getPath());
String albumArt = musicBean.getAlbumArt();
Log.i("lsh123", "playMusicInMusicBean: albumpath=="+albumArt);
Bitmap bm = BitmapFactory.decodeFile(albumArt);
Log.i("lsh123", "playMusicInMusicBean: bm=="+bm);
albumIv.setImageBitmap(bm);
playMusic();
} catch (IOException e) {
e.printStackTrace();
}
}
/*
* 点击播放按钮播放音乐，或者暂停从新播放
* 播放音乐有两种情况：
* 1.从暂停到播放
* 2.从停止到播放
* */
private void playMusic() {
/* 播放音乐的函数*/
if (mediaPlayer!=null&&!mediaPlayer.isPlaying()) {
if (currentPausePositionInSong == 0) {
try {
mediaPlayer.prepare();
mediaPlayer.start();
} catch (IOException e) {
e.printStackTrace();
}
}else{
// 从暂停到播放
mediaPlayer.seekTo(currentPausePositionInSong);
mediaPlayer.start();
}
playIv.setImageResource(R.mipmap.icon_pause);
}
}
private void pauseMusic() {
/* 暂停音乐的函数*/
if (mediaPlayer!=null&&mediaPlayer.isPlaying()) {
currentPausePositionInSong = mediaPlayer.getCurrentPosition();
mediaPlayer.pause();
playIv.setImageResource(R.mipmap.icon_play);
}
}
private void stopMusic() {
/* 停止音乐的函数*/
if (mediaPlayer!=null) {
currentPausePositionInSong = 0;
mediaPlayer.pause();
mediaPlayer.seekTo(0);
mediaPlayer.stop();
playIv.setImageResource(R.mipmap.icon_play);
}
}
@Override
protected void onDestroy() {
super.onDestroy();
stopMusic();
}
private void loadLocalMusicData() {
/* 加载本地存储当中的音乐mp3文件到集合当中*/
// 1.获取ContentResolver对象
ContentResolver resolver = getContentResolver();
// 2.获取本地音乐存储的Uri地址
Uri uri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI;
// 3 开始查询地址
Cursor cursor = resolver.query(uri, null, null, null, null);
// 4.遍历Cursor
int id = 0;
while (cursor.moveToNext()) {
String song = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.TITLE));
String singer = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.ARTIST));
String album = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.ALBUM));
id++;
String sid = String.valueOf(id);
String path = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.DATA));
long duration = cursor.getLong(cursor.getColumnIndex(MediaStore.Audio.Media.DURATION));
SimpleDateFormat sdf = new SimpleDateFormat("mm:ss");
String time = sdf.format(new Date(duration));
// 获取专辑图片主要是通过album_id进行查询
String album_id = cursor.getString(cursor.getColumnIndex(MediaStore.Audio.Media.ALBUM_ID));
String albumArt = getAlbumArt(album_id);
// 将一行当中的数据封装到对象当中
LocalMusicBean bean = new LocalMusicBean(sid, song, singer, album, time, path,albumArt);
mDatas.add(bean);
}
// 数据源变化，提示适配器更新
adapter.notifyDataSetChanged();
}
private String getAlbumArt(String album_id) {
String mUriAlbums = "content://media/external/audio/albums";
String[] projection = new String[]{"album_art"};
Cursor cur = this.getContentResolver().query(
Uri.parse(mUriAlbums + "/" + album_id),
projection, null, null, null);
String album_art = null;
if (cur.getCount() > 0 && cur.getColumnCount() > 0) {
cur.moveToNext();
album_art = cur.getString(0);
}
cur.close();
cur = null;
return album_art;
}
private void initView() {
/* 初始化控件的函数*/
nextIv = findViewById(R.id.local_music_bottom_iv_next);
playIv = findViewById(R.id.local_music_bottom_iv_play);
lastIv = findViewById(R.id.local_music_bottom_iv_last);
albumIv = findViewById(R.id.local_music_bottom_iv_icon);
singerTv = findViewById(R.id.local_music_bottom_tv_singer);
songTv = findViewById(R.id.local_music_bottom_tv_song);
musicRv = findViewById(R.id.local_music_rv);
nextIv.setOnClickListener(this);
lastIv.setOnClickListener(this);
playIv.setOnClickListener(this);
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.local_music_bottom_iv_last:
if (currnetPlayPosition ==0) {
Toast.makeText(this,"已经是第一首了，没有上一曲！",Toast.LENGTH_SHORT).show();
return;
}
currnetPlayPosition = currnetPlayPosition-1;
LocalMusicBean lastBean = mDatas.get(currnetPlayPosition);
playMusicInMusicBean(lastBean);
break;
case R.id.local_music_bottom_iv_next:
if (currnetPlayPosition ==mDatas.size()-1) {
Toast.makeText(this,"已经是最后一首了，没有下一曲！",Toast.LENGTH_SHORT).show();
return;
}
currnetPlayPosition = currnetPlayPosition+1;
LocalMusicBean nextBean = mDatas.get(currnetPlayPosition);
playMusicInMusicBean(nextBean);
break;
case R.id.local_music_bottom_iv_play:
if (currnetPlayPosition == -1) {
// 并没有选中要播放的音乐
Toast.makeText(this,"请选择想要播放的音乐",Toast.LENGTH_SHORT).show();
return;
}
if (mediaPlayer.isPlaying()) {
// 此时处于播放状态，需要暂停音乐
pauseMusic();
}else {
// 此时没有播放音乐，点击开始播放音乐
playMusic();
}
break;
}
}
}
//LocalMusicAdapter.java
package com.animee.localmusic;
import android.content.Context;
import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import java.util.List;
public class LocalMusicAdapter extends RecyclerView.Adapter{
Context context;
ListmDatas;
OnItemClickListener onItemClickListener;
public void setOnItemClickListener(OnItemClickListener onItemClickListener) {
this.onItemClickListener = onItemClickListener;
}
public interface OnItemClickListener{
public void OnItemClick(View view,int position);
}
public LocalMusicAdapter(Context context, List mDatas) {
this.context = context;
this.mDatas = mDatas;
}
@NonNull
@Override
public LocalMusicViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = LayoutInflater.from(context).inflate(R.layout.item_local_music,parent,false);
LocalMusicViewHolder holder = new LocalMusicViewHolder(view);
return holder;
}
@Override
public void onBindViewHolder(@NonNull LocalMusicViewHolder holder, final int position) {
LocalMusicBean musicBean = mDatas.get(position);
holder.idTv.setText(musicBean.getId());
holder.songTv.setText(musicBean.getSong());
holder.singerTv.setText(musicBean.getSinger());
holder.albumTv.setText(musicBean.getAlbum());
holder.timeTv.setText(musicBean.getDuration());
holder.itemView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onItemClickListener.OnItemClick(v,position);
}
});
}
@Override
public int getItemCount() {
return mDatas.size();
}
class LocalMusicViewHolder extends RecyclerView.ViewHolder{
TextView idTv,songTv,singerTv,albumTv,timeTv;
public LocalMusicViewHolder(View itemView) {
super(itemView);
idTv = itemView.findViewById(R.id.item_local_music_num);
songTv = itemView.findViewById(R.id.item_local_music_song);
singerTv = itemView.findViewById(R.id.item_local_music_singer);
albumTv = itemView.findViewById(R.id.item_local_music_album);
timeTv = itemView.findViewById(R.id.item_local_music_durtion);
}
}
}