下载图像和更新 listView 时出现问题

Question

我在下载图像和更新 ImageView 时遇到问题，我正在使用 ExecutorServices 下载图像，但我面临的问题是，就场景而言，我正在使用基本适配器在list.Image 已下载，但两张图片仅在 firstImage View 中更新。

所以位图在同一个图像视图中得到更新，有没有人遇到过类似的问题

例如，我正在下载 2 个图像，它正在创建 2 个 ImageDownloader 实例，所有运行都很好，直到 class 行中的运行()在下载部分之前，一旦下载了图像，我得到了第一个图像下载器 class 的 ImageView 的对象引用，我不确定为什么？我认为它与列表视图或适配器无关，它更多与 Executor 和运行nable Implementation 相关，

public class ImageLoader {

ExecutorService mExecutorService = null;
static ImageLoader mLoader = null;
Handler mImageHandler = null ;
DisplayMetrics mDisplayMetrics = null;
int mRequiredWidth =0 , mRequiredHeight = 0;
Map<String,ImageView> mToLoadObjects = Collections.synchronizedMap(
        new WeakHashMap<String, ImageView>());
ArrayList<String> toloadURL = new ArrayList<String>();
protected Resources mResources = null;
MyImageCache mMemoryCache;
Activity activity;
public static final String LOGGER = "ImageLoader";

public ImageLoader(Activity context){
  mExecutorService = Executors.newFixedThreadPool(5);
  mImageHandler = new Handler();
  mResources = context.getResources();
  activity = context;
  mMemoryCache  = new MyImageCache();
  mDisplayMetrics  = context.getResources().getDisplayMetrics();
  mRequiredWidth = mDisplayMetrics.widthPixels;
  mRequiredHeight = mDisplayMetrics.heightPixels;

}



public void loadImage (String url,ImageView imageView){     
    try {
        if (imageView != null) {
           if (!toloadURL.contains(url)) {
                toloadURL.add(url);
                mExecutorService.execute(new ImageDownloader(url,imageView));
            } 
        }
    }catch (Exception e){
        Log.v("Exception Occurs>>",""+e.getMessage());
    }
}




class ImageDownloader implements  Runnable{
    String imageUrl;
    ImageView downloadableImageView;
    ImageDownloader loader;


    ImageDownloader(String url,ImageView view){
        Log.v(LOGGER,"Within ImageDownloader "+url +"this>>>"+this);
        loader = this;
        imageUrl = url;
        downloadableImageView  = view;
        Log.v(LOGGER,"Within ImageDownloader "+downloadableImageView.getTag()+"this>>>"+this);
    }

    @Override
    public void run() {
        Log.v(LOGGER, "run" + downloadableImageView.getTag()+"this>>>>>"+this);
        Bitmap tempBitmap = null;
        tempBitmap = (mMemoryCache.getBitmapFromMemCache(imageUrl));
        try{
            if(tempBitmap!=null){
                Log.v(LOGGER,"ImageBitmap Wid>>>>>>"+downloadableImageView.getTag()+"this>>>>"+this+""+tempBitmap.getWidth());
                Log.v(LOGGER,"ImageBitmap Ht>>>>>>"+downloadableImageView.getTag()+ "this>>>>"+this+""+tempBitmap.getHeight());
                downloadableImageView.setImageBitmap(tempBitmap);
            }else{
                Log.v(LOGGER, "else to download Tag is" + downloadableImageView.getTag()+"this>>>>>"+this);//Works till this point

                final Bitmap tempBitmap1 = getBitmap(imageUrl);
                Log.v(LOGGER, "else to download Tag is " + downloadableImageView.getTag() + "After Download>>>" + tempBitmap1.getWidth() + "this>>>>>" + this);//Issue happens here
                mMemoryCache.addBitmapToMemoryCache(imageUrl, tempBitmap1);
                Log.v("LOGGER, else to download Tag is "+downloadableImageView.getTag()+"After Cache>>>", "" + downloadableImageView.getTag()+"this>>>>"+this);
                if(tempBitmap1!=null){
                    activity.runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            Log.v("LOGGER, else to download Tag is "+downloadableImageView.getTag()+"RunOnUIThread>>>", "" + downloadableImageView.getTag()+"this>>>>"+loader);
                            downloadableImageView.setImageBitmap(tempBitmap1);
                            downloadableImageView.requestLayout();
                        }
                    });
                }
            }
        }catch(Exception e){
            Log.v("ExceptionBitmap",""+e.getMessage());
        }

    }

    public Bitmap getBitmap(String imageUrl){
        Bitmap bitmap=null;
        try {
            Log.v("Within getBitmap ","run");
            URL uri = new URL(imageUrl);
            HttpURLConnection connection = (HttpURLConnection)uri.openConnection();
            connection.setInstanceFollowRedirects(true);
            //bitmap = BitmapFactory.decodeStream(connection.getInputStream());
             bitmap = decodeSampledBitmapFromInputStream(connection.getInputStream(), mRequiredWidth, mRequiredHeight);

        } catch (Exception e) {
           Log.v("ExceptionLoad",""+e.getMessage());
        }
        return bitmap;
    }
}

public  Bitmap decodeSampledBitmapFromInputStream(InputStream in
                                                        , int reqWidth, int reqHeight) {

    InputStream copyiInputStream1 = null;
    InputStream copyiInputStream2 = null;
    try {
        byte[] data = InputStreamTOByte(in);
        copyiInputStream1 = byteTOInputStream(data);
        copyiInputStream2 = byteTOInputStream(data);
    } catch (Exception e) {
        e.printStackTrace();
    }
    final BitmapFactory.Options options = new BitmapFactory.Options();
    options.inJustDecodeBounds = true;
    BitmapFactory.decodeStream(copyiInputStream1, null, options);

    // Calculate inSampleSize
    options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);

    // Decode bitmap with inSampleSize set
    options.inJustDecodeBounds = false;
    return BitmapFactory.decodeStream(copyiInputStream2, null, options);
}

public static int calculateInSampleSize(
        BitmapFactory.Options options, int reqWidth, int reqHeight) {
    // Raw height and width of image
    final int height = options.outHeight;
    final int width = options.outWidth;
    int inSampleSize = 1;

    if (height > reqHeight || width > reqWidth) {

        final int halfHeight = height / 2;
        final int halfWidth = width / 2;

        // Calculate the largest inSampleSize value that is a power of 2 and keeps both
        // height and width larger than the requested height and width.
        while ((halfHeight / inSampleSize) > reqHeight
                && (halfWidth / inSampleSize) > reqWidth) {
            inSampleSize *= 2;
        }
    }

    return inSampleSize;
}

public InputStream byteTOInputStream(byte[] in) throws Exception{

    ByteArrayInputStream is = new ByteArrayInputStream(in);
    return is;
}

public byte[] InputStreamTOByte(InputStream in) throws IOException {

    ByteArrayOutputStream outStream = new ByteArrayOutputStream();
    byte[] data = new byte[1024*16];
    int count = -1;
    while((count = in.read(data,0,1024*16)) != -1)
        outStream.write(data, 0, count);

    data = null;
    return outStream.toByteArray();
}


class BitmapUpdater implements Runnable
{
    Bitmap bitmap;
    ImageView imageView;

    public BitmapUpdater(Bitmap bitmap, ImageView imageView){
        bitmap=bitmap;
        imageView =imageView;
    }
    public void run()
    {
        // Show bitmap on UI
        if(bitmap!=null){
            activity.runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    imageView.setImageBitmap(bitmap);
                }
            });
        }
        else
            imageView.setImageResource(R.drawable.account_photo_book_detail2);
    }
}

}

我附上日志供参考，请帮忙解决这个问题

Image Tag(0,1)--> I applied Tag for ImageView to sort out the Image View instance

线程 1:(ImageDownloader1 线程对象)

04-06 17:05:57.662 20053-20053/com.xxx.xxxxmobileapp V/ImageLoader﹕ImageDownloader内https://lh6.googleusercontent.com/-8HO-4vIFnlw/URquZnsFgtI/AAAAAAAAAbs/WT8jViTF7vw/s1024/Antelope%252520Hallway.jpgthis>>>com.xxx.xxxxmobileapp.Imagebook.network. ImageLoader$ImageDownloader@435058b0 04-06 17:05:57.662 20053-20053/com.xxx.xxxxmobileapp V/ImageLoader﹕ImageDownloader内0(imageViewObjectTag)this>>>com.xxx.xxxxmobileapp.Imagebook.network.ImageLoader$ImageDownloader@

04-06 17:05:57.664 20053-20130/com.xxx.xxxxmobileapp V/ImageLoader：else要下载的Tag是0(imageViewObjectTag)this>>>>>com.xxx.xxxxmobileapp。 Imagebook.network.ImageLoader$ImageDownloader@435058b0

线程 2:((ImageDownloader2 线程对象))

04-06 17:05:57.666 20053-20053/com.xxx.xxxxmobileapp V/ImageLoader﹕ImageDownloader内https://lh5.googleusercontent.com/-7qZeDtRKFKc/URquWZT1gOI/AAAAAAAAAbs/hqWgteyNXsg/s1024/Another%252520Rockaway%252520Sunset.jpgthis>>>com.xxx.xxxxmobileapp.Imagebook.network.图片加载器$ImageDownloader@431a5d58 04-06 17:05:57.666 20053-20053/com.xxx.xxxxmobileapp V/ImageLoader﹕ImageDownloader内1(imageView)this>>>com.xxx.xxxxmobileapp.Imagebook.network.ImageLoader$ImageDownloader@431a5d58

线程 1 和 2 运行 ():

20053-20130/com.xxx.xxxxmobileapp V/ImageLoader﹕ 运行 0(imageViewObjectTag)这个>>>>>com.xxx.xxxxmobileapp.Imagebook.network.ImageLoader$ImageDownloader@435058b0 20053-20131/com.xxx.xxxxmobileapp V/ImageLoader﹕运行 1(imageViewObjectTag)这个>>>>>com.xxx.xxxxmobileapp.Imagebook.network.ImageLoader$ImageDownloader@431a5d58

其他下载标签是1this>>>>>com.xxx.xxxxmobileapp.Imagebook.network.ImageLoader$ImageDownloader@431a5d58

((ImageDownloader1 线程对象)) 下载后：

else to download Tag is 0(imageViewObjectTag)After Download>>>1024this>>>>>com.xxx.xxxxmobileapp.Imagebook.network.ImageLoader$ImageDownloader@435058b0//(ImageDownloader1 Object)) else to download Tag is 0(imageViewObjectTag)After Cache>>>: 0this>>>>com.xxx.xxxxmobileapp.Imagebook.network.ImageLoader$ImageDownloader@435058b0//(ImageDownloader1 Object)) else to download Tag is 0(imageViewObjectTag)运行OnUIThread>>>: 0this>>>>com.xxx.xxxxmobileapp.Imagebook.network.ImageLoader$ImageDownloader@435058b0//(ImageDownloader1 Object))

一切都好到此为止

((ImageDownloader2 线程对象))下载后：

else to download Tag is 0(imageViewObjectTag)After Download>>>1024this>>>>>com.xxx.xxxxmobileapp.Imagebook.network.ImageLoader$ImageDownloader@431a5d58//(ImageDownloader2 Object with ImageView tag coming as 0 不同，应该是 tag1)) else to download Tag is 0(imageViewObjectTag)After Cache>>>: 0this>>>>com.xxx.xxxxmobileapp.Imagebook.network.ImageLoader$ImageDownloader@431a5d58 //(ImageDownloader2 Object with ImageView tag coming as 0 different which should be标签 1)) else to download Tag is 0(imageViewObjectTag)运行OnUIThread>>>: 0this>>>>com.xxx.xxxxmobileapp.Imagebook.network.ImageLoader$ImageDownloader@431a5d58//(ImageDownloader2 Object with ImageView tag coming as 0不同，应该是 tag1))

Answer 1

我认为这是一个回收问题，问题在于下载完成后最初的ImageView可能代表列表中的另一个位置。您看到问题发生在 getBitmap(imageUrl) 调用之后，但理论上，它也可能更早发生。我不确定你的代码中是否使用了BitmapUpdater，但乍一看，它与你的情况无关。

因此，为了解决这个问题，您需要实施一种机制来避免 ImageView 被更新为 "old" 位图。您可以使用 ImageView 的 tag 属性来保存实际需要显示的 URL。如果图片的 tag 中的 URL 与实际用于下载的不同，则缓存图片即可。你可以做类似

的事情

public void loadImage (String url,ImageView imageView){
    if(imageView != null) imageView.setTag(url);
    [...]
}

和

if(tempBitmap1!=null){
    activity.runOnUiThread(new Runnable() {
        @Override
        public void run() {
            Log.v("LOGGER, else to download Tag is " + downloadableImageView.getTag()+"RunOnUIThread>>>", "" + downloadableImageView.getTag()+"this>>>>"+loader);
            if(downloadableImageView.getTag().equals(imageUrl) {
                downloadableImageView.setImageBitmap(tempBitmap1);
            }
            else Log.v(LOGGER, "the image no longer wants this URL, ignoring");
            //downloadableImageView.requestLayout();
        }
    });
}

此外，我建议避免 downloadableImageView.requestLayout();，因为它会导致测量整个布局，而在您的情况下，则不需要。

Answer 2

图片下载为什么不用Glide库？

它在一行中完成所有事情。

这是它的语法

Glide.with(context).load(URL).into(Imageview);

Answer 3

是的，最后我通过我的朋友解决了这个问题arunkumar

向他致敬:)

我尝试了两件事，

1) 找出问题出在列表视图或执行程序服务 implementation.To 发现我用线性布局替换了列表视图并添加为成功工作的视图，这确认问题出在列表视图而不是执行器服务实现。

2) 图像在第一个图像中更新的真正问题是因为视图 ID(ImageView.getID()) 相同，

我设置了 ID 而不是设置标签，我将 ID 传递给图像加载器 class，我通过 findViewById(SetID) 检索了图像，这有效

我正在添加一些有用的代码

用于在适配器中设置 ID class:

 final ImageView imageView = holder.jobImageView;
       holder.jobImageView.setId(position);
       loader.loadImage(object.getlargeImageUrl(),holder.jobImageView,position);

获取适配器中的 ID class:

final Bitmap tempBitmap1 = getBitmap(imageUrl);
                Log.v(LOGGER, "else to download Tag is " +imageViewId + "After Download>>>" + tempBitmap1.getWidth() + "this>>>>>" + this);
                mMemoryCache.addBitmapToMemoryCache(imageUrl, tempBitmap1);
                downloadableImageView = (ImageView)activity.findViewById(imageViewId);
                Log.v("LOGGER, else to download Tag is "+downloadableImageView.getTag()+"After Cache>>>", "" + downloadableImageView.getTag()+"this>>>>"+this);
                if(tempBitmap1!=null){
                    activity.runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            Log.v("LOGGER, else to download Tag is " + downloadableImageView.getTag() + "RunOnUIThread>>>", "" + downloadableImageView.getTag() + "this>>>>" + loader);

                            downloadableImageView.setImageBitmap(tempBitmap1);
                            //downloadableImageView.requestLayout();
                        }
                    });
                }

Answer 4

可以使用毕加索图片加载库
Link 用于 Picasso

的文档

Answer 5

像解码本地存储或在线流中的大位图这样繁重的工作，我们必须在工作线程中完成，问题是解码完成后，imageview 已被回收。解决它：

// In your adapter (onCreateView)
bitmap = yourBitmapCache.get(position);
if (bitmap != null)
    yourImageView.setImageBitmap(bitmap);
else if (imageLoaderManager.isLoading.get(position) == false){
    imagerLoaderManager.load(position, url);
}


// Create Callback interface
interface Callback {
     void onFinishLoad(int position, Bitmap bm);
}

// Create inner class ImageLoaderManager
class ImageLoaderManager {
    Hasmap<Integer, Boolean> isLoading = new Hasmap<>();
    Callback callback = new Callback() {
         @Override
         void onFinishLoad(int position, Bitmap bitmap){
             isLoading.put(position, false);
             if (bitmap != null) {
                  yourBitmapCache.put(position, bitmap)
                  activity.runOnUiThread(new Runnable() {
                       @Override
                       public void run(){
                            notifyDataSetInvalidated();
                            // If you use recycler view adapter: notifyItemChanged(position)
                       }
                  });

             }
         }
    };

    public void load(int position, String url){
         isLoading.put(position, true);
         newYourImageLoader(url, position, callback).start();
         // when loader finish job, 
         // it's must call back using callback.onFinishLoad(given position, bitmap result);
    }
}

无需在我的解决方案中保留 ImageView 引用。请记住 position 并要求适配器在解码任务完成后重新加载此位置的项目视图，现在位图已经存在于 yourBitmapCache.

下载图像和更新 listView 时出现问题

Issue in Downloading the Image and Updating the listView

android

listview

executorservice

runnable