Android MediaPlayer 音乐播放器扫描本地音乐、上一曲、下一曲切歌、播放本地音乐（下）-阿里云开发者社区

样式文件：

rounded_corners.xml 水波纹效果的xml文件

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true">
        <shape android:shape="rectangle">
            <solid android:color="#18ffc400"/>
        </shape>
    </item>
    <item android:state_focused="true" android:state_enabled="true">
        <shape android:shape="rectangle">
            <solid android:color="#0f000000"/>
        </shape>
    </item>
</selector>

在bg_white.xml中调用了rounded_corners.xml

bg_white.xml代码如下：

<?xml version="1.0" encoding="utf-8"?>
<ripple xmlns:android="http://schemas.android.com/apk/res/android"
    android:color="#20000000"
    android:drawable="@drawable/rounded_corners"/>

扫描按钮的背景图

scan_finish_btn_bg_pressed.9

scan_finish_btn_bg_normal.9

selector_scan_btn.xml使用上面两个图片的按钮点击样式

<?xml version="1.0" encoding="utf-8"?>
<selector
  xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true" android:drawable="@drawable/scan_finish_btn_bg_pressed" />
    <item android:drawable="@drawable/scan_finish_btn_bg_normal" />
</selector>

selector_scan_btn这个样式文件，在activity_main中用到

seekbar_style.xml 进度条样式

<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@android:id/background">
        <shape>
            <corners android:radius="5dp" />
            <solid android:color="#B6C4F9" />
        </shape>
    </item>
    <item android:id="@android:id/secondaryProgress">
        <clip>
            <shape>
                <corners android:radius="5dp" />
                <solid android:color="#B6C4F9" />
            </shape>
        </clip>
    </item>
    <item android:id="@android:id/progress">
        <clip>
            <shape>
                <corners android:radius="5dp" />
                <solid android:color="#7D95F3" />
            </shape>
        </clip>
    </item>
</layer-list>

thumb.xml 进度条滑块样式

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval">
    <solid android:color="#40DEF1" />
    <size
        android:width="10dp"
        android:height="10dp" />
    <stroke
        android:width="1dp"
        android:color="#40DEF1" />
</shape>

上面两个关于进度条的样式也在activity_main.xml中用到

然后是values下面的styles.xml文件

<resources>
    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/white</item>
        <item name="colorPrimaryDark">@color/white</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>
    <style name="AppTheme.PopupOverlay" parent="ThemeOverlay.AppCompat.Light" />
</resources>

样式和布局讲完了，接下来是工具类:

Constant.java 缓存字符工具类，因为现在只在MainActivity中用到，所以提现不出它的优势，代码如下：

public class Constant {
    public final static String MUSIC_DATA_FIRST = "musicDataFirst";
}

DateUtil.java 时间转换工具类：

/**
 * 时间转换工具类
 */
public class DateUtil {
    //获取当前完整的日期和时间
    public static String getNowDateTime(){
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy:MM:dd HH:mm:ss");
        return sdf.format(new Date());
    }
    //获取当前日期
    public static String getNowDate(){
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd");
        return sdf.format(new Date());
    }
    //获取当前时间
    public static String getNowTime(){
        SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss");
        return sdf.format(new Date());
    }
    //获取当前时间不包含秒
    public static String getNowTimeM(){
        SimpleDateFormat sdf = new SimpleDateFormat("HH:mm");
        return sdf.format(new Date());
    }
    //转换当前时间不包含时
    public static String parseTime(int oldTime) {
        SimpleDateFormat sdf = new SimpleDateFormat("mm:ss");// 时间格式
        String newTime = sdf.format(new Date(oldTime));
        return newTime;
    }
    //获取当前日期(精确到毫秒)
    public static String getNowTimeDetail(){
        SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss:SSS");
        return sdf.format(new Date());
    }
    //获取当前日期是星期几
    public static String getWeekOfDate(Date date) {
        String[] weekDays = { "星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六" };
        Calendar cal = Calendar.getInstance();
        cal.setTime(date);
        int w = cal.get(Calendar.DAY_OF_WEEK) - 1;
        if (w < 0)
            w = 0;
        return weekDays[w];
    }
    //将时间戳转化为对应的时间(10位或者13位都可以)
    public static String formatTime(long time){
        String times = null;
        if(String.valueOf(time).length()>10){// 10位的秒级别的时间戳
            times = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date(time * 1000));
        }else {// 13位的秒级别的时间戳
            times  = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(time);
        }
        return times;
    }
    //将时间字符串转为时间戳字符串
    public static String getStringTimestamp(String time) {
        String timestamp = null;
        try {
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            Long longTime = sdf.parse(time).getTime()/1000;
            timestamp = Long.toString(longTime);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return timestamp;
    }
    //将长整型时间转为为分秒
    public static String time(long millionSeconds) {
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("mm:ss");
        Calendar c = Calendar.getInstance();
        c.setTimeInMillis(millionSeconds);
        return simpleDateFormat.format(c.getTime());
    }
    //将长度转换为时间
    public static StringBuilder mFormatBuilder = new StringBuilder();
    public static Formatter mFormatter = new Formatter(mFormatBuilder, Locale.getDefault());
    public static String stringForTime(int timeMs) {
        int totalSeconds = timeMs / 1000;
        int seconds = totalSeconds % 60;
        int minutes = (totalSeconds / 60) % 60;
        int hours = totalSeconds / 3600;
        mFormatBuilder.setLength(0);
        if (hours > 0) {
            return mFormatter.format("%d:%02d:%02d", hours, minutes, seconds).toString();
        } else {
            return mFormatter.format("%02d:%02d", minutes, seconds).toString();
        }
    }
}

MusicUtils.java 音乐扫描工具类

public class MusicUtils {
    /**
     * 扫描系统里面的音频文件，返回一个list集合
     */
    public static List<Song> getMusicData(Context context) {
        List<Song> list = new ArrayList<Song>();
        // 媒体库查询语句（写一个工具类MusicUtils）
        Cursor cursor = context.getContentResolver().query(MediaStore.Audio.Media.EXTERNAL_CONTENT_URI, null, null,
                null, MediaStore.Audio.AudioColumns.IS_MUSIC);
        if (cursor != null) {
            while (cursor.moveToNext()) {
                Song song = new Song();
                song.song = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Audio.Media.TITLE));//歌曲名称
                song.singer = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Audio.Media.ARTIST));//歌手
                song.album = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Audio.Media.ALBUM));//专辑名
                song.path = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Audio.Media.DATA));//歌曲路径
                song.duration = cursor.getInt(cursor.getColumnIndexOrThrow(MediaStore.Audio.Media.DURATION));//歌曲时长
                song.size = cursor.getLong(cursor.getColumnIndexOrThrow(MediaStore.Audio.Media.SIZE));//歌曲大小
                if (song.size > 1000 * 800) {
                    // 注释部分是切割标题，分离出歌曲名和歌手 （本地媒体库读取的歌曲信息不规范）
                    if (song.song.contains("-")) {
                        String[] str = song.song.split("-");
                        song.singer = str[0];
                        song.song = str[1];
                    }
                    list.add(song);
                }
            }
            // 释放资源
            cursor.close();
        }
        return list;
    }
    //专辑图片
    private static String imgUrl(Context context){
        String album_art= null;
        String[] mediaColumns1 = new String[] {MediaStore.Audio.Albums.ALBUM_ART, MediaStore.Audio.Albums.ALBUM};
        Cursor cursor1 = context.getContentResolver().query(MediaStore.Audio.Albums.EXTERNAL_CONTENT_URI, mediaColumns1, null, null,
                null);
        if (cursor1 != null) {
            cursor1.moveToFirst();
            do {
                album_art =  cursor1.getString(0);
                if (album_art != null) {
                    Log.d("ALBUM_ART", album_art);
                }
                String album =  cursor1.getString(1);
                if (album != null) {
                    Log.d("ALBUM_ART", album);
                }
            } while (cursor1.moveToNext());
            cursor1.close();
        }
        return album_art;
    }
    /**
     * 定义一个方法用来格式化获取到的时间
     */
    public static String formatTime(int time) {
        if (time / 1000 % 60 < 10) {
            return time / 1000 / 60 + ":0" + time / 1000 % 60;
        } else {
            return time / 1000 / 60 + ":" + time / 1000 % 60;
        }
    }

ObjectUtil.java 对象工具类，用于判空

public final class ObjectUtils {
    private ObjectUtils() {
        throw new UnsupportedOperationException("u can't instantiate me...");
    }
    /**
     * Return whether object is empty.
     *
     * @param obj The object.
     * @return {@code true}: yes<br>{@code false}: no
     */
    public static boolean isEmpty(final Object obj) {
        if (obj == null) {
            return true;
        }
        if (obj.getClass().isArray() && Array.getLength(obj) == 0) {
            return true;
        }
        if (obj instanceof CharSequence && obj.toString().length() == 0) {
            return true;
        }
        if (obj instanceof Collection && ((Collection) obj).isEmpty()) {
            return true;
        }
        if (obj instanceof Map && ((Map) obj).isEmpty()) {
            return true;
        }
        if (obj instanceof SimpleArrayMap && ((SimpleArrayMap) obj).isEmpty()) {
            return true;
        }
        if (obj instanceof SparseArray && ((SparseArray) obj).size() == 0) {
            return true;
        }
        if (obj instanceof SparseBooleanArray && ((SparseBooleanArray) obj).size() == 0) {
            return true;
        }
        if (obj instanceof SparseIntArray && ((SparseIntArray) obj).size() == 0) {
            return true;
        }
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR2) {
            if (obj instanceof SparseLongArray && ((SparseLongArray) obj).size() == 0) {
                return true;
            }
        }
        if (obj instanceof LongSparseArray && ((LongSparseArray) obj).size() == 0) {
            return true;
        }
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
            if (obj instanceof android.util.LongSparseArray
                    && ((android.util.LongSparseArray) obj).size() == 0) {
                return true;
            }
        }
        return false;
    }
    public static boolean isEmpty(final CharSequence obj) {
        return obj == null || obj.toString().length() == 0;
    }
    public static boolean isEmpty(final Collection obj) {
        return obj == null || obj.isEmpty();
    }
    public static boolean isEmpty(final Map obj) {
        return obj == null || obj.isEmpty();
    }
    public static boolean isEmpty(final SimpleArrayMap obj) {
        return obj == null || obj.isEmpty();
    }
    public static boolean isEmpty(final SparseArray obj) {
        return obj == null || obj.size() == 0;
    }
    public static boolean isEmpty(final SparseBooleanArray obj) {
        return obj == null || obj.size() == 0;
    }
    public static boolean isEmpty(final SparseIntArray obj) {
        return obj == null || obj.size() == 0;
    }
    public static boolean isEmpty(final LongSparseArray obj) {
        return obj == null || obj.size() == 0;
    }
    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
    public static boolean isEmpty(final SparseLongArray obj) {
        return obj == null || obj.size() == 0;
    }
    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
    public static boolean isEmpty(final android.util.LongSparseArray obj) {
        return obj == null || obj.size() == 0;
    }
    /**
     * Return whether object is not empty.
     *
     * @param obj The object.
     * @return {@code true}: yes<br>{@code false}: no
     */
    public static boolean isNotEmpty(final Object obj) {
        return !isEmpty(obj);
    }
    public static boolean isNotEmpty(final CharSequence obj) {
        return !isEmpty(obj);
    }
    public static boolean isNotEmpty(final Collection obj) {
        return !isEmpty(obj);
    }
    public static boolean isNotEmpty(final Map obj) {
        return !isEmpty(obj);
    }
    public static boolean isNotEmpty(final SimpleArrayMap obj) {
        return !isEmpty(obj);
    }
    public static boolean isNotEmpty(final SparseArray obj) {
        return !isEmpty(obj);
    }
    public static boolean isNotEmpty(final SparseBooleanArray obj) {
        return !isEmpty(obj);
    }
    public static boolean isNotEmpty(final SparseIntArray obj) {
        return !isEmpty(obj);
    }
    public static boolean isNotEmpty(final LongSparseArray obj) {
        return !isEmpty(obj);
    }
    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN_MR2)
    public static boolean isNotEmpty(final SparseLongArray obj) {
        return !isEmpty(obj);
    }
    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
    public static boolean isNotEmpty(final android.util.LongSparseArray obj) {
        return !isEmpty(obj);
    }
    /**
     * Return whether object1 is equals to object2.
     *
     * @param o1 The first object.
     * @param o2 The second object.
     * @return {@code true}: yes<br>{@code false}: no
     */
    public static boolean equals(final Object o1, final Object o2) {
        return o1 == o2 || (o1 != null && o1.equals(o2));
    }
    /**
     * Require the objects are not null.
     *
     * @param objects The object.
     * @throws NullPointerException if any object is null in objects
     */
    public static void requireNonNull(final Object... objects) {
        if (objects == null) throw new NullPointerException();
        for (Object object : objects) {
            if (object == null) throw new NullPointerException();
        }
    }
    /**
     * Return the nonnull object or default object.
     *
     * @param object        The object.
     * @param defaultObject The default object to use with the object is null.
     * @param <T>           The value type.
     * @return the nonnull object or default object
     */
    public static <T> T getOrDefault(final T object, final T defaultObject) {
        if (object == null) {
            return defaultObject;
        }
        return object;
    }
    /**
     * Return the hash code of object.
     *
     * @param o The object.
     * @return the hash code of object
     */
    public static int hashCode(final Object o) {
        return o != null ? o.hashCode() : 0;
    }
}

SPUtils.java 缓存读写工具类，配合Constant使效果更佳

/**
 * sharepref工具类
 */
public class SPUtils {
    private static final String NAME="config";
    public static void putBoolean(String key, boolean value, Context context) {
        SharedPreferences sp = context.getSharedPreferences(NAME,
                Context.MODE_PRIVATE);
        sp.edit().putBoolean(key, value).commit();
    }
    public static boolean getBoolean(String key, boolean defValue, Context context) {
        SharedPreferences sp = context.getSharedPreferences(NAME,
                Context.MODE_PRIVATE);
        return sp.getBoolean(key, defValue);
    }
    public static void putString(String key, String value, Context context) {
        SharedPreferences sp = context.getSharedPreferences(NAME,
                Context.MODE_PRIVATE);
        sp.edit().putString(key, value).commit();
    }
    public static String getString(String key, String defValue, Context context) {
        if(context!=null){
            SharedPreferences sp = context.getSharedPreferences(NAME,
                    Context.MODE_PRIVATE);
            return sp.getString(key, defValue);
        }
        return "";
    }
    public static void putInt(String key, int value, Context context) {
        SharedPreferences sp = context.getSharedPreferences(NAME,
                Context.MODE_PRIVATE);
        sp.edit().putInt(key, value).commit();
    }
    public static int getInt(String key, int defValue, Context context) {
        SharedPreferences sp = context.getSharedPreferences(NAME,
                Context.MODE_PRIVATE);
        return sp.getInt(key, defValue);
    }
    public static void remove(String key, Context context) {
        SharedPreferences sp = context.getSharedPreferences(NAME,
                Context.MODE_PRIVATE);
        sp.edit().remove(key).commit();
    }
}

StatusBarUtil.java 状态栏工具类：

public class StatusBarUtil {
    /**
     * 修改状态栏为全透明
     *
     * @param activity
     */
    @TargetApi(19)
    public static void transparencyBar(Activity activity) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            Window window = activity.getWindow();
            window.clearFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
            window.getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN
                    | View.SYSTEM_UI_FLAG_LAYOUT_STABLE);
            window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
            window.setStatusBarColor(Color.TRANSPARENT);
        } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            Window window = activity.getWindow();
            window.setFlags(WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS,
                    WindowManager.LayoutParams.FLAG_TRANSLUCENT_STATUS);
        }
    }
    /**
     * 修改状态栏颜色，支持4.4以上版本
     *
     * @param activity
     * @param colorId
     */
    public static void setStatusBarColor(Activity activity, int colorId) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            Window window = activity.getWindow();
//      window.addFlags(WindowManager.LayoutParams.FLAG_DRAWS_SYSTEM_BAR_BACKGROUNDS);
            window.setStatusBarColor(activity.getResources().getColor(colorId));
        } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            //使用SystemBarTint库使4.4版本状态栏变色，需要先将状态栏设置为透明
            transparencyBar(activity);
            SystemBarTintManager tintManager = new SystemBarTintManager(activity);
            tintManager.setStatusBarTintEnabled(true);
            tintManager.setStatusBarTintResource(colorId);
        }
    }
    /**
     * 状态栏亮色模式，设置状态栏黑色文字、图标，
     * 适配4.4以上版本MIUIV、Flyme和6.0以上版本其他Android
     *
     * @param activity
     * @return 1:MIUUI 2:Flyme 3:android6.0
     */
    public static int StatusBarLightMode(Activity activity) {
        int result = 0;
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            if (MIUISetStatusBarLightMode(activity, true)) {
                result = 1;
            } else if (FlymeSetStatusBarLightMode(activity.getWindow(), true)) {
                result = 2;
            } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                activity.getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN | View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR);
                result = 3;
            }
        }
        return result;
    }
    /**
     * 已知系统类型时，设置状态栏黑色文字、图标。
     * 适配4.4以上版本MIUIV、Flyme和6.0以上版本其他Android
     *
     * @param activity
     * @param type     1:MIUUI 2:Flyme 3:android6.0
     */
    public static void StatusBarLightMode(Activity activity, int type) {
        if (type == 1) {
            MIUISetStatusBarLightMode(activity, true);
        } else if (type == 2) {
            FlymeSetStatusBarLightMode(activity.getWindow(), true);
        } else if (type == 3) {
            activity.getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN | View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR);
        }
    }
    /**
     * 状态栏暗色模式，清除MIUI、flyme或6.0以上版本状态栏黑色文字、图标
     */
    public static void StatusBarDarkMode(Activity activity, int type) {
        if (type == 1) {
            MIUISetStatusBarLightMode(activity, false);
        } else if (type == 2) {
            FlymeSetStatusBarLightMode(activity.getWindow(), false);
        } else if (type == 3) {
            activity.getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_VISIBLE);
        }
    }
    /**
     * 设置状态栏图标为深色和魅族特定的文字风格
     * 可以用来判断是否为Flyme用户
     *
     * @param window 需要设置的窗口
     * @param dark   是否把状态栏文字及图标颜色设置为深色
     * @return boolean 成功执行返回true
     */
    public static boolean FlymeSetStatusBarLightMode(Window window, boolean dark) {
        boolean result = false;
        if (window != null) {
            try {
                WindowManager.LayoutParams lp = window.getAttributes();
                Field darkFlag = WindowManager.LayoutParams.class
                        .getDeclaredField("MEIZU_FLAG_DARK_STATUS_BAR_ICON");
                Field meizuFlags = WindowManager.LayoutParams.class
                        .getDeclaredField("meizuFlags");
                darkFlag.setAccessible(true);
                meizuFlags.setAccessible(true);
                int bit = darkFlag.getInt(null);
                int value = meizuFlags.getInt(lp);
                if (dark) {
                    value |= bit;
                } else {
                    value &= ~bit;
                }
                meizuFlags.setInt(lp, value);
                window.setAttributes(lp);
                result = true;
            } catch (Exception e) {
            }
        }
        return result;
    }
    /**
     * 需要MIUIV6以上
     *
     * @param activity
     * @param dark     是否把状态栏文字及图标颜色设置为深色
     * @return boolean 成功执行返回true
     */
    public static boolean MIUISetStatusBarLightMode(Activity activity, boolean dark) {
        boolean result = false;
        Window window = activity.getWindow();
        if (window != null) {
            Class clazz = window.getClass();
            try {
                int darkModeFlag = 0;
                Class layoutParams = Class.forName("android.view.MiuiWindowManager$LayoutParams");
                Field field = layoutParams.getField("EXTRA_FLAG_STATUS_BAR_DARK_MODE");
                darkModeFlag = field.getInt(layoutParams);
                Method extraFlagField = clazz.getMethod("setExtraFlags", int.class, int.class);
                if (dark) {
                    extraFlagField.invoke(window, darkModeFlag, darkModeFlag);//状态栏透明且黑色字体
                } else {
                    extraFlagField.invoke(window, 0, darkModeFlag);//清除黑色字体
                }
                result = true;
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                    //开发版 7.7.13 及以后版本采用了系统API，旧方法无效但不会报错，所以两个方式都要加上
                    if (dark) {
                        activity.getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN | View.SYSTEM_UI_FLAG_LIGHT_STATUS_BAR);
                    } else {
                        activity.getWindow().getDecorView().setSystemUiVisibility(View.SYSTEM_UI_FLAG_VISIBLE);
                    }
                }
            } catch (Exception e) {
            }
        }
        return result;
    }
}

ToastUtils.java Toast消息类，原来的太麻烦了，

public class ToastUtils {
    public static void showLongToast(Context context, CharSequence llw) {
        Toast.makeText(context.getApplicationContext(), llw, Toast.LENGTH_LONG).show();
    }
    public static void showShortToast(Context context, CharSequence llw) {
        Toast.makeText(context.getApplicationContext(), llw, Toast.LENGTH_SHORT).show();
    }
}

工具类介绍完成，接下来是数据模型：

Song.java 歌曲工具类：

public class Song {
    /**
     * 歌手
     */
    public String singer;
    /**
     * 歌曲名
     */
    public String song;
    /**
     * 专辑名
     */
    public String album;
    /**
     * 专辑图片
     */
    public String album_art;
    /**
     * 歌曲的地址
     */
    public String path;
    /**
     * 歌曲长度
     */
    public int duration;
    /**
     * 歌曲的大小
     */
    public long size;
    public String getSinger() {
        return singer;
    }
    public void setSinger(String singer) {
        this.singer = singer;
    }
    public String getSong() {
        return song;
    }
    public void setSong(String song) {
        this.song = song;
    }
    public String getPath() {
        return path;
    }
    public void setPath(String path) {
        this.path = path;
    }
    public int getDuration() {
        return duration;
    }
    public void setDuration(int duration) {
        this.duration = duration;
    }
    public long getSize() {
        return size;
    }
    public void setSize(long size) {
        this.size = size;
    }
    public String getAlbum() {
        return album;
    }
    public void setAlbum(String album) {
        this.album = album;
    }
    public String getAlbum_art() {
        return album_art;
    }
    public void setAlbum_art(String album_art) {
        this.album_art = album_art;
    }
}

MusicListAdapter.java 歌曲列表适配器

public class MusicListAdapter extends BaseQuickAdapter<Song, BaseViewHolder>{
    public MusicListAdapter(int layoutResId, @Nullable List<Song> data) {
        super(layoutResId, data);
    }
    @Override
    protected void convert(BaseViewHolder helper, Song item) {
        //给控件赋值
        int duration = item.duration;
        String time = MusicUtils.formatTime(duration);
        helper.setText(R.id.tv_song_name,item.getSong().trim())//歌曲名称
                .setText(R.id.tv_singer,item.getSinger()+" - "+item.getAlbum())//歌手 - 专辑
                .setText(R.id.tv_duration_time,time)//歌曲时间
                //歌曲序号，因为getAdapterPosition得到的位置是从0开始，故而加1，
                //是因为位置和1都是整数类型，直接赋值给TextView会报错，故而拼接了""
                .setText(R.id.tv_position,helper.getAdapterPosition()+1+"");
        helper.addOnClickListener(R.id.item_music);//给item添加点击事件，点击之后传递数据到播放页面或者在本页面进行音乐播放
    }
}

然后是主角出场了：

MainActivity.java 主要逻辑代码都在里面：

注释也已经写好了，我就不过多的啰嗦了，代码如下：

package com.llw.music;
import android.Manifest;
import android.graphics.drawable.Drawable;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.SeekBar;
import android.widget.TextView;
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;
import com.chad.library.adapter.base.BaseQuickAdapter;
import com.llw.music.adapter.MusicListAdapter;
import com.llw.music.model.Song;
import com.llw.music.utils.Constant;
import com.llw.music.utils.MusicUtils;
import com.llw.music.utils.ObjectUtils;
import com.llw.music.utils.SPUtils;
import com.llw.music.utils.StatusBarUtil;
import com.llw.music.utils.ToastUtils;
import com.tbruyelle.rxpermissions2.RxPermissions;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import butterknife.BindView;
import butterknife.ButterKnife;
import butterknife.OnClick;
import static com.llw.music.utils.DateUtil.parseTime;
public class MainActivity extends AppCompatActivity implements MediaPlayer.OnCompletionListener {
    @BindView(R.id.rv_music)
    RecyclerView rvMusic;
    @BindView(R.id.btn_scan)
    Button btnScan;
    @BindView(R.id.scan_lay)
    LinearLayout scanLay;
    @BindView(R.id.tv_clear_list)
    TextView tvClearList;
    @BindView(R.id.tv_title)
    TextView tvTitle;
    @BindView(R.id.toolbar)
    Toolbar toolbar;
    @BindView(R.id.tv_play_time)
    TextView tvPlayTime;
    @BindView(R.id.time_seekBar)
    SeekBar timeSeekBar;
    @BindView(R.id.tv_total_time)
    TextView tvTotalTime;
    @BindView(R.id.btn_previous)
    ImageView btnPrevious;
    @BindView(R.id.btn_play_or_pause)
    ImageView btnPlayOrPause;
    @BindView(R.id.btn_next)
    ImageView btnNext;
    @BindView(R.id.tv_play_song_info)
    TextView tvPlaySongInfo;
    @BindView(R.id.play_state_img)
    ImageView playStateImg;
    @BindView(R.id.play_state_lay)
    LinearLayout playStateLay;
    private MusicListAdapter mAdapter;//歌曲适配器
    private List<Song> mList;//歌曲列表
    private RxPermissions rxPermissions;//权限请求
    private MediaPlayer mediaPlayer;//音频播放器
    private String musicData = null;
    // 记录当前播放歌曲的位置
    public int mCurrentPosition;
    private static final int INTERNAL_TIME = 1000;// 音乐进度间隔时间
    private Handler mHandler = new Handler(new Handler.Callback() {
        @Override
        public boolean handleMessage(Message message) {
            // 展示给进度条和当前时间
            int progress = mediaPlayer.getCurrentPosition();
            timeSeekBar.setProgress(progress);
            tvPlayTime.setText(parseTime(progress));
            // 继续定时发送数据
            updateProgress();
            return true;
        }
    });
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ButterKnife.bind(this);
        StatusBarUtil.StatusBarLightMode(this);
        rxPermissions = new RxPermissions(this);//使用前先实例化
        timeSeekBar.setOnSeekBarChangeListener(seekBarChangeListener);//滑动条监听
        musicData = SPUtils.getString(Constant.MUSIC_DATA_FIRST, "yes", this);
        if (musicData.equals("no")) {//说明是第一次打开APP，未进行扫描
            scanLay.setVisibility(View.GONE);
            initMusic();
        } else {
            scanLay.setVisibility(View.VISIBLE);
        }
    }
    private void permissionRequest() {//使用这个框架需要制定JDK版本，建议用1.8
        rxPermissions.request(Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE)
                .subscribe(granted -> {
                    if (granted) {//请求成功之后开始扫描
                        initMusic();
                    } else {//失败时给一个提示
                        ToastUtils.showShortToast(MainActivity.this, "未授权");
                    }
                });
    }
    //获取音乐列表
    private void initMusic() {
        mList = new ArrayList<>();//实例化
        //数据赋值
        mList = MusicUtils.getMusicData(this);//将扫描到的音乐赋值给音乐列表
        if (!ObjectUtils.isEmpty(mList) && mList != null) {
            scanLay.setVisibility(View.GONE);
            SPUtils.putString(Constant.MUSIC_DATA_FIRST, "no", this);
        }
        mAdapter = new MusicListAdapter(R.layout.item_music_rv_list, mList);//指定适配器的布局和数据源
        //线性布局管理器，可以设置横向还是纵向，RecyclerView默认是纵向的，所以不用处理,如果不需要设置方向，代码还可以更加的精简如下
        rvMusic.setLayoutManager(new LinearLayoutManager(this));
        //如果需要设置方向显示，则将下面代码注释去掉即可
//        LinearLayoutManager manager = new LinearLayoutManager(this);
//        manager.setOrientation(RecyclerView.HORIZONTAL);
//        rvMusic.setLayoutManager(manager);
        //设置适配器
        rvMusic.setAdapter(mAdapter);
        //item的点击事件
        mAdapter.setOnItemChildClickListener(new BaseQuickAdapter.OnItemChildClickListener() {
            @Override
            public void onItemChildClick(BaseQuickAdapter adapter, View view, int position) {
                if (view.getId() == R.id.item_music) {
                    mCurrentPosition = position;
                    changeMusic(mCurrentPosition);
//                    mAdapter.notifyItemRangeChanged(0, mList.size());
                }
            }
        });
        //设置背景样式
        initStyle();
    }
    private void initStyle() {
        //toolbar背景变透明
        toolbar.setBackgroundColor(getResources().getColor(R.color.half_transparent));
        //文字变白色
        tvTitle.setTextColor(getResources().getColor(R.color.white));
        tvClearList.setTextColor(getResources().getColor(R.color.white));
        StatusBarUtil.transparencyBar(this);
    }
    @OnClick({R.id.tv_clear_list, R.id.btn_scan, R.id.btn_previous, R.id.btn_play_or_pause, R.id.btn_next})
    public void onViewClicked(View view) {
        switch (view.getId()) {
            case R.id.tv_clear_list://清空数据
                mList.clear();
                mAdapter.notifyDataSetChanged();
                SPUtils.putString(Constant.MUSIC_DATA_FIRST, "yes", this);
                scanLay.setVisibility(View.VISIBLE);
                toolbar.setBackgroundColor(getResources().getColor(R.color.white));
                StatusBarUtil.StatusBarLightMode(this);
                tvTitle.setTextColor(getResources().getColor(R.color.black));
                tvClearList.setTextColor(getResources().getColor(R.color.black));
                if (mediaPlayer == null) {
                    mediaPlayer = new MediaPlayer();
                }
                if (mediaPlayer.isPlaying()) {
                    mediaPlayer.pause();
                    mediaPlayer.reset();
                }
                break;
            case R.id.btn_scan://扫描本地歌曲
                permissionRequest();
                break;
            case R.id.btn_previous://上一曲
                changeMusic(--mCurrentPosition);//当前歌曲位置减1
                break;
            case R.id.btn_play_or_pause://播放或者暂停
                // 首次点击播放按钮，默认播放第0首，下标从0开始
                if (mediaPlayer == null) {
                    changeMusic(0);
                } else {
                    if (mediaPlayer.isPlaying()) {
                        mediaPlayer.pause();
                        btnPlayOrPause.setBackground(getResources().getDrawable(R.mipmap.icon_pause));
                        playStateImg.setBackground(getResources().getDrawable(R.mipmap.list_play_state));
                        //如果你是用TextView的leftDrawable设置的图片，在代码里面就可以通过下面代码来动态更换
//                        Drawable leftImg = getResources().getDrawable(R.mipmap.list_play_state);
//                        leftImg.setBounds(0, 0, leftImg.getMinimumWidth(), leftImg.getMinimumHeight());
//                        tvPlaySongInfo.setCompoundDrawables(leftImg, null, null, null);
                    } else {
                        mediaPlayer.start();
                        btnPlayOrPause.setBackground(getResources().getDrawable(R.mipmap.icon_play));
                        playStateImg.setBackground(getResources().getDrawable(R.mipmap.list_pause_state));
                    }
                }
                break;
            case R.id.btn_next://下一曲
                changeMusic(++mCurrentPosition);//当前歌曲位置加1
                break;
        }
    }
    //切歌
    private void changeMusic(int position) {
        Log.e("MainActivity", "position:" + position);
        if (position < 0) {
            mCurrentPosition = position = mList.size() - 1;
            Log.e("MainActivity", "mList.size:" + mList.size());
        } else if (position > mList.size() - 1) {
            mCurrentPosition = position = 0;
        }
        Log.e("MainActivity", "position:" + position);
        if (mediaPlayer == null) {
            mediaPlayer = new MediaPlayer();
        }
        try {
            // 切歌之前先重置，释放掉之前的资源
            mediaPlayer.reset();
            // 设置播放源
            Log.d("Music", mList.get(position).path);
            mediaPlayer.setDataSource(mList.get(position).path);
            tvPlaySongInfo.setText("歌名： " + mList.get(position).song +
                    "  歌手： " + mList.get(position).singer);
//            Glide.with(this).load(mList.get(position).album_art).into(songImage);
            tvPlaySongInfo.setSelected(true);//跑马灯效果
            playStateLay.setVisibility(View.VISIBLE);
            // 开始播放前的准备工作，加载多媒体资源，获取相关信息
            mediaPlayer.prepare();
            // 开始播放
            mediaPlayer.start();
        } catch (IOException e) {
            e.printStackTrace();
        }
        // 切歌时重置进度条并展示歌曲时长
        timeSeekBar.setProgress(0);
        timeSeekBar.setMax(mediaPlayer.getDuration());
        tvTotalTime.setText(parseTime(mediaPlayer.getDuration()));
        updateProgress();
        if (mediaPlayer.isPlaying()) {
            btnPlayOrPause.setBackground(getResources().getDrawable(R.mipmap.icon_play));
            playStateImg.setBackground(getResources().getDrawable(R.mipmap.list_pause_state));
        } else {
            btnPlayOrPause.setBackground(getResources().getDrawable(R.mipmap.icon_pause));
            playStateImg.setBackground(getResources().getDrawable(R.mipmap.list_play_state));
        }
    }
    private void updateProgress() {
        // 使用Handler每间隔1s发送一次空消息，通知进度条更新
        Message msg = Message.obtain();// 获取一个现成的消息
        // 使用MediaPlayer获取当前播放时间除以总时间的进度
        int progress = mediaPlayer.getCurrentPosition();
        msg.arg1 = progress;
        mHandler.sendMessageDelayed(msg, INTERNAL_TIME);
    }
    //滑动条监听
    SeekBar.OnSeekBarChangeListener seekBarChangeListener = new SeekBar.OnSeekBarChangeListener() {
        @Override
        public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
        }
        @Override
        public void onStartTrackingTouch(SeekBar seekBar) {
        }
        // 当手停止拖拽进度条时执行该方法
        // 获取拖拽进度
        // 将进度对应设置给MediaPlayer
        @Override
        public void onStopTrackingTouch(SeekBar seekBar) {
            int progress = seekBar.getProgress();
            mediaPlayer.seekTo(progress);
        }
    };
    //播放完成之后自动下一曲
    @Override
    public void onCompletion(MediaPlayer mp) {
        changeMusic(++mCurrentPosition);
    }
}

Android MediaPlayer 音乐播放器扫描本地音乐、上一曲、下一曲切歌、播放本地音乐（下）

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