Question

我有一个应用程序从服务器下载图像，将它们存储在SD卡上，然后以幻灯片形式显示给用户。该应用程序有许多不同的幻灯片，用户可以查看。我的问题是，在我查看几个画廊后，我发现内存不足错误。我做了很多谷歌搜索，并阅读了Romain Guy的Avoiding Memory Leaks文章大约20次。我试图复制他的unbindDrawables（）方法，但是无法在Gallery对象上调用removeAllViews（）。我也尝试在所有位图上调用recycle（）但是当我在适配器中的位图上执行时，应用程序会在打开图库时立即抛出错误。我也尝试重新编码幻灯片，以便在适配器外部创建所有位图，然后将它们作为数组传递 - 这允许我遍历我的位图数组并在幻灯片中的onDestroy方法中对每个位图调用recycle（）活动 - 但这实际上似乎使泄漏变得更糟。

以下是我的幻灯片活动的代码：

public class Slideshow extends Activity {
    static String galleryId;
    public static final int MSG_DOWNLOADED = 0;
    static  Handler handler;
    static Gallery g;
    static ArrayList<String> filePaths;
    static String subFolder;
    static ArrayList<String>  imageToGet;
    static LinearLayout pb;
    static boolean firstTime = true;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
            setContentView(R.layout.slideshow);
            Context context = getApplicationContext();


            Bundle extras = getIntent().getExtras();

            if(extras != null){
            galleryId = extras.getString("galleryId");
            }
            pb = (LinearLayout) findViewById(R.id.progress); 
             handler = new Handler(){
                    @Override
                    public void handleMessage(Message msg){
                        switch (msg.what){
                        case MSG_DOWNLOADED:
                            g.setAdapter(new SlideshowAdapter(getApplicationContext(), R.id.gallery, filePaths));
                            pb.setVisibility(8);
                            if(firstTime){
                            Thread images = new Thread(){
                                public void run(){
                                    ImageGallery gallery = XMLParser.getGalleryById(galleryId, false, getApplicationContext());
                                    ArrayList<String> imageURLs = gallery.getImageURLs();
                                    String subFolder = "gallery"+galleryId+"/";
                                    getImages(imageURLs, subFolder, false);
                                }
                            };
                            images.start();
                            firstTime = false;
                            }
                            break;
                        }
                    }
                };
            ImageGallery gallery = XMLParser.getGalleryById(galleryId, false, context);
            filePaths = gallery.getFilePaths();
            ArrayList<String> imageURLs = gallery.getImageURLs();
            subFolder = "gallery"+galleryId+"/";
            g = (Gallery) findViewById(R.id.gallery);
            if(filePaths.size() > 0){
            String filePath = filePaths.get(0);
            String url = imageURLs.get(0);
            imageToGet = new ArrayList<String>();
            imageToGet.add(url);

            if(filePaths.size() == 1 ){
                File file = new File(filePath);
                if(!file.exists()){
                    Thread getFirstImage = new Thread(){
                        public void  run(){
                            Log.d("ClubSlideshow getting only image", ""+imageToGet.get(0));
                            getImages(imageToGet, subFolder, false);
                            handler.sendEmptyMessage(MSG_DOWNLOADED);
                        }
                    };
                    getFirstImage.start();
                }

            }else if(filePaths.size()>1){
                String filePath2 = filePaths.get(1);
                String url2 = imageURLs.get(1);
                File file = new File(filePath);
                File file2 = new File(filePath2);
                imageToGet.add(url2);
                if(!file.exists()||!file2.exists()){
                    Thread getFirstImage = new Thread(){
                        public void  run(){
                            getImages(imageToGet, subFolder, false);
                            handler.sendEmptyMessage(MSG_DOWNLOADED);
                        }
                    };
                    getFirstImage.start();
                }

            }
            }


    }

    public void getImages(ArrayList<String> imageURLs, String subFolder, boolean force){
        DataCache.downloadFromUrlArray(imageURLs, subFolder, force, getApplicationContext());
    }

    public class ImageThread implements Runnable{
        public ImageThread(ArrayList<String> imageURLs, String subFolder, Boolean force){
            getImages(imageURLs, subFolder, force);
        }

        public void run(){

        }
    }

    @Override
    protected void onDestroy(){
        super.onDestroy();
        g.setAdapter(null);
    }

}

这是我的SlideshowAdapter类的代码：

public class SlideshowAdapter extends ArrayAdapter<String> {
    int mGalleryItemBackground;
    private Context mContext;
    private ArrayList<String> images = new ArrayList<String>();
    Bitmap bMap;
    String filePath;
    File file;
    ImageView i;

    public SlideshowAdapter(Context c, int resourceId, ArrayList<String> objects){
        super(c, resourceId, objects);
        this.mContext = c;
        this.images = objects;
    }


    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        if(convertView !=null){
            i = (ImageView) convertView;
        }else{
            i = new ImageView(mContext);
        }

        filePath = mContext.getFilesDir()+"/"+images.get(position);

        file = new File(filePath);
        if(file.exists()){
            bMap = BitmapFactory.decodeFile(filePath);
            i.setImageBitmap(bMap);
        }

        i.setScaleType(ImageView.ScaleType.FIT_CENTER);

        return i;
    }

}

有人能看到可能导致记忆问题的原因吗？

Answer 1

实际上有几个问题：

图库视图缓存已损坏，因此每次调用getView方法时都会如此 convertView为null请参阅this bug
在适配器中，在每个getView方法调用上分配新的位图所以然后滚动发生相同的位图一次又一次地解码所以从我的角度来看，你应该尝试在你的适配器中实现你自己的Bitmap缓存，这样内存不会被相同的位图对象推翻

Answer 2

您可以尝试使用 scaledBitmap 来减少内存使用量

if(file.exists()){ 
            bMap = BitmapFactory.decodeFile(filePath); 
            i.setImageBitmap(bMap); 
        }

到

if(file.exists()){ 
            bMap = BitmapFactory.decodeFile(filePath); 
            bMap = Bitmap.createScaledBitmap(bMap, 100, 100, true);
            i.setImageBitmap(bMap); 
        }

Answer 3

尝试将图像存储在SD卡或设备内存中以避免此问题。

Android：在Gallery中使用位图的outOfMemoryError

3 个答案: