android 内存泄漏处理方式

由于某个对象持有了其他对象的引用导致，导致无法 GC。

1:合理的使用context–比如我们常使用的Toast,Service,最好使用getApplicationContext(),因为这些在activity结束的时候可能仍在运行
下图通过图片说明国关于context的使用)

2:不要在activity中使用AsyncTask的强引用,如下是不行的:

class MyActivity extends Activity {  private AsyncTask myTask = new AsyncTask() {    //内部类隐含了对activity的一个强引用,强引用是无法被gc回收的;  }}

我们异步获取手机音频文件做个小范例：

 private static class ScanRingsPhoneMusic extends AsyncTask {        private WeakReference activityReference;        // only retain a weak reference to the activity        ScanRingsPhoneMusic(MusicListActivity context) {            activityReference = new WeakReference<>(context);        }        @Override        protected Void doInBackground(Void... voids) {            MusicListActivity activity = activityReference.get();            getAllSongs(activity);            return null;        }    }    @Override    protected void onDestroy() {        super.onDestroy();        PublicUtils.getInstance().mediaPlayerRelease();        mHandler.removeCallbacksAndMessages(null);    }    public static void  getAllSongs(MusicListActivity activity) {        Cursor cursor = activity.getApplicationContext().getContentResolver().query(                MediaStore.Audio.Media.EXTERNAL_CONTENT_URI,                new String[] { MediaStore.Audio.Media._ID,                        MediaStore.Audio.Media.DISPLAY_NAME,                        MediaStore.Audio.Media.TITLE,                        MediaStore.Audio.Media.DURATION,                        MediaStore.Audio.Media.ARTIST,                        MediaStore.Audio.Media.ALBUM,                        MediaStore.Audio.Media.YEAR,                        MediaStore.Audio.Media.MIME_TYPE,                        MediaStore.Audio.Media.SIZE,                        MediaStore.Audio.Media.DATA },                MediaStore.Audio.Media.MIME_TYPE + "=? or "                        + MediaStore.Audio.Media.MIME_TYPE + "=?",                new String[] { "audio/mpeg", "audio/x-ms-wma" }, null);        if (cursor.moveToFirst()) {            BackGroundMusic backGroundMusic = null;            while (cursor.moveToNext()) {                backGroundMusic = new BackGroundMusic();                // 文件名                backGroundMusic.setFileName(cursor.getString(1));                // 歌曲名                backGroundMusic.setTitle(cursor.getString(2));                // 时长                backGroundMusic.setDuration(cursor.getInt(3));                // 歌手名                backGroundMusic.setSinger(cursor.getString(4));                // 专辑名                backGroundMusic.setAlbum(cursor.getString(5));                // 年代                if (cursor.getString(6) != null) {                    backGroundMusic.setYear(cursor.getString(6));                } else {                    backGroundMusic.setYear("未知");                }                // 歌曲格式                if ("audio/mpeg".equals(cursor.getString(7).trim())) {                    backGroundMusic.setType("mp3");                } else if ("audio/x-ms-wma".equals(cursor.getString(7).trim())) {                    backGroundMusic.setType("wma");                }                // 文件大小                if (cursor.getString(8) != null) {                    float size = cursor.getInt(8) / 1024f / 1024f;                    backGroundMusic.setSize((size + "").substring(0, 4) + "M");                } else {                    backGroundMusic.setSize("未知");                }                // 文件路径                if (cursor.getString(9) != null) {                    backGroundMusic.setFilePath(cursor.getString(9));                }                    Message message = activity.mHandler.obtainMessage();                    message.what = 1;                    message.obj=backGroundMusic;                    activity.mHandler.sendMessage(message);                Log.i(TAG, backGroundMusic.toString());            }            cursor.close();        }        return ;    }

最后附加一个防止handler 内存泄漏的code

 /**     * weakReference 防止内存泄漏     */    private static class MyHandler extends Handler {        private WeakReference weakReference;         MyHandler(MusicListActivity activity) {            weakReference = new WeakReference<>(activity);        }        @Override        public void handleMessage(Message msg) {            super.handleMessage(msg);            Log.e(TAG, "handleMessage: ");            MusicListActivity activity = weakReference.get();            switch (msg.what) {                case 1:                    if (activity != null) {                        BackGroundMusic backGroundMusic= (BackGroundMusic) msg.obj;                        activity.mBackGroundMusicList.add( backGroundMusic);                        if(activity.mBackGroundMusicList.size()>0){                            activity.musicAdapter.notifyDataSetChanged();                        }                    }                    break;                case 2:                    activity.musicAdapter.notifyDataSetChanged();                    break;            }        }    }

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