universal image loader在listview/gridview中滚动时重复加载图片的问题及解决方法

    public void displayImage(String uri, ImageView imageView, DisplayImageOptions options) {
        displayImage(uri, new ImageViewAware(imageView), options, null, null);
    }

public ViewAware(View view) {
        this(view, true);
    }

    /**
     * Constructor
     *
     * @param view                {@link android.view.View View} to work with
     * @param checkActualViewSize <b>true</b> - then {@link #getWidth()} and {@link #getHeight()} will check actual
     *                            size of View. It can cause known issues like
     *                            <a href="https://github.com/nostra13/Android-Universal-Image-Loader/issues/376">this</a>.
     *                            But it helps to save memory because memory cache keeps bitmaps of actual (less in
     *                            general) size.
     *                            <p/>
     *                            <b>false</b> - then {@link #getWidth()} and {@link #getHeight()} will <b>NOT</b>
     *                            consider actual size of View, just layout parameters. <br /> If you set ‘false‘
     *                            it‘s recommended ‘android:layout_width‘ and ‘android:layout_height‘ (or
     *                            ‘android:maxWidth‘ and ‘android:maxHeight‘) are set with concrete values. It helps to
     *                            save memory.
     */
    public ViewAware(View view, boolean checkActualViewSize) {
        if (view == null) throw new IllegalArgumentException("view must not be null");

        this.viewRef = new WeakReference<View>(view);
        this.checkActualViewSize = checkActualViewSize;
    }

ImageAware imageAware = new ImageViewAware(imageView, false);
imageLoader.displayImage(imageUri, imageAware);

File cacheDir = StorageUtils.getOwnCacheDirectory(getApplicationContext(), "imageloader/Cache"); //缓存文件的存放地址
ImageLoaderConfiguration config = new ImageLoaderConfiguration 
.Builder(getApplicationContext()) 
.memoryCacheExtraOptions(480, 800) // max width, max height 
.threadPoolSize(3)//线程池内加载的数量 
.threadPriority(Thread.NORM_PRIORITY - 2)  //降低线程的优先级保证主UI线程不受太大影响
.denyCacheImageMultipleSizesInMemory() 
.memoryCache(new LruMemoryCache(5 * 1024 * 1024)) //建议内存设在5-10M,可以有比较好的表现
.memoryCacheSize(5 * 1024 * 1024) 
.discCacheSize(50 * 1024 * 1024) 
.discCacheFileNameGenerator(new Md5FileNameGenerator()) 
.tasksProcessingOrder(QueueProcessingType.LIFO) 
.discCacheFileCount(100) //缓存的文件数量 
.discCache(new UnlimitedDiscCache(cacheDir)) 
.defaultDisplayImageOptions(DisplayImageOptions.createSimple()) 
.imageDownloader(new BaseImageDownloader(getApplicationContext(), 5 * 1000, 30 * 1000)) // connectTimeout (5 s), readTimeout (30 s)
.writeDebugLogs() // Remove for release app 
.build();

options = new DisplayImageOptions.Builder()
.showStubImage(R.drawable.default_cover)
.showImageForEmptyUri(R.drawable.default_cover)
.showImageOnFail(R.drawable.default_cover)
.cacheInMemory(true)
.cacheOnDisc(true)
.imageScaleType(ImageScaleType.NONE)
.bitmapConfig(Bitmap.Config.RGB_565)//设置为RGB565比起默认的ARGB_8888要节省大量的内存
.delayBeforeLoading(100)//载入图片前稍做延时可以提高整体滑动的流畅度
.build();

setOnScrollListener(new PauseOnScrollListener(imageLoader, true, true));//两个分别表示拖动下拉条和滑动过程中暂停加载