Android - UniversalMusicPlayer 代码

1、LogHelper

package com.example.android.uamp.utils;

import android.util.Log;

import com.example.android.uamp.BuildConfig;

public class LogHelper {

    private static final String LOG_PREFIX = "uamp_";
    private static final int LOG_PREFIX_LENGTH = LOG_PREFIX.length();
    private static final int MAX_LOG_TAG_LENGTH = 23;

    public static String makeLogTag(String str) {
        if (str.length() > MAX_LOG_TAG_LENGTH - LOG_PREFIX_LENGTH) {
            return LOG_PREFIX + str.substring(0, MAX_LOG_TAG_LENGTH - LOG_PREFIX_LENGTH - 1);
        }

        return LOG_PREFIX + str;
    }

    /**
     * Don't use this when obfuscating class names!
     */
    public static String makeLogTag(Class cls) {
        return makeLogTag(cls.getSimpleName());
    }


    public static void v(String tag, Object... messages) {
        // Only log VERBOSE if build type is DEBUG
        if (BuildConfig.DEBUG) {
            log(tag, Log.VERBOSE, null, messages);
        }
    }

    public static void d(String tag, Object... messages) {
        // Only log DEBUG if build type is DEBUG
        if (BuildConfig.DEBUG) {
            log(tag, Log.DEBUG, null, messages);
        }
    }

    public static void i(String tag, Object... messages) {
        log(tag, Log.INFO, null, messages);
    }

    public static void w(String tag, Object... messages) {
        log(tag, Log.WARN, null, messages);
    }

    public static void w(String tag, Throwable t, Object... messages) {
        log(tag, Log.WARN, t, messages);
    }

    public static void e(String tag, Object... messages) {
        log(tag, Log.ERROR, null, messages);
    }

    public static void e(String tag, Throwable t, Object... messages) {
        log(tag, Log.ERROR, t, messages);
    }

    public static void log(String tag, int level, Throwable t, Object... messages) {
        if (Log.isLoggable(tag, level)) {
            String message;
            if (t == null && messages != null && messages.length == 1) {
                // handle this common case without the extra cost of creating a stringbuffer:
                message = messages[0].toString();
            } else {
                StringBuilder sb = new StringBuilder();
                if (messages != null) for (Object m : messages) {
                    sb.append(m);
                }
                if (t != null) {
                    sb.append("\n").append(Log.getStackTraceString(t));
                }
                message = sb.toString();
            }
            Log.println(level, tag, message);
        }
    }
}

2、ImageCache

package com.example.android.uamp;

import android.graphics.Bitmap;
import android.os.AsyncTask;
import android.util.LruCache;

import com.example.android.uamp.utils.BitmapHelper;
import com.example.android.uamp.utils.LogHelper;

import java.io.IOException;

/**
 * Implements a basic cache of album arts, with async loading support.
 */
public final class AlbumArtCache {
    private static final String TAG = LogHelper.makeLogTag(AlbumArtCache.class);

    private static final int MAX_ALBUM_ART_CACHE_SIZE = 12*1024*1024;  // 12 MB
    private static final int MAX_ART_WIDTH = 800;  // pixels
    private static final int MAX_ART_HEIGHT = 480;  // pixels

    // Resolution reasonable for carrying around as an icon (generally in
    // MediaDescription.getIconBitmap). This should not be bigger than necessary, because
    // the MediaDescription object should be lightweight. If you set it too high and try to
    // serialize the MediaDescription, you may get FAILED BINDER TRANSACTION errors.
    private static final int MAX_ART_WIDTH_ICON = 128;  // pixels
    private static final int MAX_ART_HEIGHT_ICON = 128;  // pixels

    private static final int BIG_BITMAP_INDEX = 0;
    private static final int ICON_BITMAP_INDEX = 1;

    private final LruCache<String, Bitmap[]> mCache;

    private static final AlbumArtCache sInstance = new AlbumArtCache();

    public static AlbumArtCache getInstance() {
        return sInstance;
    }

    private AlbumArtCache() {
        // Holds no more than MAX_ALBUM_ART_CACHE_SIZE bytes, bounded by maxmemory/4 and
        // Integer.MAX_VALUE:
        int maxSize = Math.min(MAX_ALBUM_ART_CACHE_SIZE,
            (int) (Math.min(Integer.MAX_VALUE, Runtime.getRuntime().maxMemory()/4)));
        mCache = new LruCache<String, Bitmap[]>(maxSize) {
            @Override
            protected int sizeOf(String key, Bitmap[] value) {
                return value[BIG_BITMAP_INDEX].getByteCount()
                    + value[ICON_BITMAP_INDEX].getByteCount();
            }
        };
    }

    public Bitmap getBigImage(String artUrl) {
        Bitmap[] result = mCache.get(artUrl);
        return result == null ? null : result[BIG_BITMAP_INDEX];
    }

    public Bitmap getIconImage(String artUrl) {
        Bitmap[] result = mCache.get(artUrl);
        return result == null ? null : result[ICON_BITMAP_INDEX];
    }

    public void fetch(final String artUrl, final FetchListener listener) {
        // WARNING: for the sake of simplicity, simultaneous multi-thread fetch requests
        // are not handled properly: they may cause redundant costly operations, like HTTP
        // requests and bitmap rescales. For production-level apps, we recommend you use
        // a proper image loading library, like Glide.
        Bitmap[] bitmap = mCache.get(artUrl);
        if (bitmap != null) {
            LogHelper.d(TAG, "getOrFetch: album art is in cache, using it", artUrl);
            listener.onFetched(artUrl, bitmap[BIG_BITMAP_INDEX], bitmap[ICON_BITMAP_INDEX]);
            return;
        }
        LogHelper.d(TAG, "getOrFetch: starting asynctask to fetch ", artUrl);

        new AsyncTask<Void, Void, Bitmap[]>() {
            @Override
            protected Bitmap[] doInBackground(Void[] objects) {
                Bitmap[] bitmaps;
                try {
                    Bitmap bitmap = BitmapHelper.fetchAndRescaleBitmap(artUrl,
                        MAX_ART_WIDTH, MAX_ART_HEIGHT);
                    Bitmap icon = BitmapHelper.scaleBitmap(bitmap,
                        MAX_ART_WIDTH_ICON, MAX_ART_HEIGHT_ICON);
                    bitmaps = new Bitmap[] {bitmap, icon};
                    mCache.put(artUrl, bitmaps);
                } catch (IOException e) {
                    return null;
                }
                LogHelper.d(TAG, "doInBackground: putting bitmap in cache. cache size=" +
                    mCache.size());
                return bitmaps;
            }

            @Override
            protected void onPostExecute(Bitmap[] bitmaps) {
                if (bitmaps == null) {
                    listener.onError(artUrl, new IllegalArgumentException("got null bitmaps"));
                } else {
                    listener.onFetched(artUrl,
                        bitmaps[BIG_BITMAP_INDEX], bitmaps[ICON_BITMAP_INDEX]);
                }
            }
        }.execute();
    }

    public static abstract class FetchListener {
        public abstract void onFetched(String artUrl, Bitmap bigImage, Bitmap iconImage);
        public void onError(String artUrl, Exception e) {
            LogHelper.e(TAG, e, "AlbumArtFetchListener: error while downloading " + artUrl);
        }
    }
}

3、BitmapHelper

package com.example.android.uamp.utils;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;

import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class BitmapHelper {
    private static final String TAG = LogHelper.makeLogTag(BitmapHelper.class);

    // Max read limit that we allow our input stream to mark/reset.
    private static final int MAX_READ_LIMIT_PER_IMG = 1024 * 1024;

    public static Bitmap scaleBitmap(Bitmap src, int maxWidth, int maxHeight) {
       double scaleFactor = Math.min(
           ((double) maxWidth)/src.getWidth(), ((double) maxHeight)/src.getHeight());
        return Bitmap.createScaledBitmap(src,
            (int) (src.getWidth() * scaleFactor), (int) (src.getHeight() * scaleFactor), false);
    }

    public static Bitmap scaleBitmap(int scaleFactor, InputStream is) {
        // Get the dimensions of the bitmap
        BitmapFactory.Options bmOptions = new BitmapFactory.Options();

        // Decode the image file into a Bitmap sized to fill the View
        bmOptions.inJustDecodeBounds = false;
        bmOptions.inSampleSize = scaleFactor;

        return BitmapFactory.decodeStream(is, null, bmOptions);
    }

    public static int findScaleFactor(int targetW, int targetH, InputStream is) {
        // Get the dimensions of the bitmap
        BitmapFactory.Options bmOptions = new BitmapFactory.Options();
        bmOptions.inJustDecodeBounds = true;
        BitmapFactory.decodeStream(is, null, bmOptions);
        int actualW = bmOptions.outWidth;
        int actualH = bmOptions.outHeight;

        // Determine how much to scale down the image
        return Math.min(actualW/targetW, actualH/targetH);
    }

    @SuppressWarnings("SameParameterValue")
    public static Bitmap fetchAndRescaleBitmap(String uri, int width, int height)
            throws IOException {
        URL url = new URL(uri);
        BufferedInputStream is = null;
        try {
            HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
            is = new BufferedInputStream(urlConnection.getInputStream());
            is.mark(MAX_READ_LIMIT_PER_IMG);
            int scaleFactor = findScaleFactor(width, height, is);
            LogHelper.d(TAG, "Scaling bitmap ", uri, " by factor ", scaleFactor, " to support ",
                    width, "x", height, "requested dimension");
            is.reset();
            return scaleBitmap(scaleFactor, is);
        } finally {
            if (is != null) {
                is.close();
            }
        }
    }
}

4、网络是否正常

package com.example.android.uamp.utils;

import android.content.Context;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;

/**
 * Generic reusable network methods.
 */
public class NetworkHelper {
    /**
     * @param context to use to check for network connectivity.
     * @return true if connected, false otherwise.
     */
    public static boolean isOnline(Context context) {
        ConnectivityManager connMgr = (ConnectivityManager)
            context.getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = connMgr.getActiveNetworkInfo();
        return (networkInfo != null && networkInfo.isConnected());
    }
}

5、从主题中获取颜色值

public class ResourceHelper {
    /**
     * Get a color value from a theme attribute.
     * @param context used for getting the color.
     * @param attribute theme attribute.
     * @param defaultColor default to use.
     * @return color value
     */
    public static int getThemeColor(Context context, int attribute, int defaultColor) {
        int themeColor = 0;
        String packageName = context.getPackageName();
        try {
            Context packageContext = context.createPackageContext(packageName, 0);
            ApplicationInfo applicationInfo =
                context.getPackageManager().getApplicationInfo(packageName, 0);
            packageContext.setTheme(applicationInfo.theme);
            Resources.Theme theme = packageContext.getTheme();
            TypedArray ta = theme.obtainStyledAttributes(new int[] {attribute});
            themeColor = ta.getColor(0, defaultColor);
            ta.recycle();
        } catch (PackageManager.NameNotFoundException e) {
            e.printStackTrace();
        }
        return themeColor;
    }
}