Android Volley不缓存图像

问题描述

我使用了此教程，以使用Volley在网格中显示和缓存图像.当互联网连接时，它可以正常工作.但是断开图像连接后不显示.看来Volley并没有缓存任何图像.问题是，没有有关使用Volley缓存图像的完整文档.这是我的代码:

I used this tutorial to show and cache image in grid using Volley. when internet is connected , it works fine .but after disconnecting the image do not show.it seems Volley do not cache any image. the problem is, there is no complete documentation about caching image using Volley.here is my code :

xml:

<android.support.v4.widget.DrawerLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/drawer_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <LinearLayout
        android:id="@+id/container_toolbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <include
            android:id="@+id/toolbar"
            layout="@layout/toolbar" />
    </LinearLayout>


    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="#F4F4F6"
        android:paddingTop="@dimen/activity_vertical_margin"
        tools:context=".Content_Gallery_Activity">

        <TextView
            android:id="@+id/text_gallery_title"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:layout_alignParentTop="true"
            android:layout_centerHorizontal="true"
            android:gravity="center"
            android:paddingLeft="10dp"
            android:paddingRight="10dp"
            android:textAppearance="?android:attr/textAppearanceSmall" />

        <RelativeLayout
            android:id="@+id/relative_gallery"
            android:layout_width="match_parent"
            android:layout_height="80dp"
            android:layout_below="@+id/text_gallery_title"
            android:layout_marginLeft="8dp"
            android:layout_marginRight="8dp"
            android:layout_marginTop="10dp"
            android:background="@drawable/rect_lst_tree"
            android:paddingLeft="10dp"
            android:paddingRight="10dp" >

            <com.beardedhen.androidbootstrap.AwesomeTextView
                android:id="@+id/font_time"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerVertical="true"
                android:layout_toLeftOf="@+id/tv_date_gallery"
                app:bootstrapBrand="info"
                app:fontAwesomeIcon="fa_clock_o"
                >
            </com.beardedhen.androidbootstrap.AwesomeTextView>

            <TextView
                android:id="@+id/tv_date_gallery"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentRight="true"
                android:layout_centerVertical="true"
                android:layout_marginLeft="5dp"
                android:textAppearance="?android:attr/textAppearanceSmall"
                android:textColor="#1B131B"
                android:textSize="13dp" >
            </TextView>

            <TextView
                android:id="@+id/text_image_count"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerVertical="true"
                android:layout_marginLeft="10dp"
                android:layout_toRightOf="@+id/gallery_thumb"
                android:text="Small"
                android:textAppearance="?android:attr/textAppearanceSmall"
                android:textColor="#F01435"
                android:textSize="12dp" />

            <ir.whc.news.views.CircularNetworkImageView
                android:id="@+id/gallery_thumb"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentLeft="true"
                android:layout_centerVertical="true"
                >
            </ir.whc.news.views.CircularNetworkImageView>
        </RelativeLayout>

        <GridView
            android:id="@+id/gridView1"
            android:layout_width="match_parent"
            android:layout_height="fill_parent"
            android:layout_below="@+id/relative_gallery"
            android:columnWidth="100dp"
            android:horizontalSpacing="1dp"
            android:numColumns="auto_fit"
            android:paddingTop="10dp"
            android:stretchMode="spacingWidthUniform"
            android:verticalSpacing="8dp" >
        </GridView>

    </RelativeLayout>
</LinearLayout>


<fragment
    android:id="@+id/fragment_navigation_drawer"
    android:name="ir.whc.news.activity.FragmentDrawer"
    android:layout_width="@dimen/nav_drawer_width"
    android:layout_height="match_parent"
    android:layout_gravity="start"
    app:layout="@layout/fragment_navigation_drawer"
    tools:layout="@layout/fragment_navigation_drawer" />

活动:

    grd.setAdapter(new MyImageAdapter(galleryItem.get_images()));
        grd.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                Intent intent = new Intent(ContentGalleryActivity.this, DisplayImageActivity.class);
                intent.putExtra("largimage_url", galleryItem.get_images().get(position).get_largimage_path());
                startActivity(intent);
            }
        });

适配器:

    class MyImageAdapter extends BaseAdapter {

        ArrayList<ImageItem> imageItems;

        public MyImageAdapter(ArrayList<ImageItem> imageItems)
        {
            this.imageItems=imageItems;
        }

        @Override
        public int getCount() {
            return imageItems.size();
        }

        @Override
        public Object getItem(int position) {
            return imageItems.get(position);
        }

        @Override
        public long getItemId(int position) {
            return imageItems.get(position).get_id();
        }

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

            View view = convertView;
            final ViewHolder gridViewImageHolder;
//            check to see if we have a view
            if (view == null) {
                view = getLayoutInflater().inflate(R.layout.grid_image_item, parent, false);
                gridViewImageHolder = new ViewHolder();
                gridViewImageHolder.imageView = (ImageView) view.findViewById(R.id.image_grid_networkImageView);
                view.setTag(gridViewImageHolder);
            } else {
                gridViewImageHolder = (ViewHolder) view.getTag();
            }

            mNetworkImageView = (NetworkImageView) gridViewImageHolder.imageView;
            mNetworkImageView.setDefaultImageResId(R.drawable.ic_launcher);
            mNetworkImageView.setErrorImageResId(android.R.drawable.ic_dialog_alert);
            mNetworkImageView.setAdjustViewBounds(true);
            mNetworkImageView.setImageUrl(imageItems.get(position).get_thumb_path(), imageLoader);

            return view;
        }
    }

Imageloder :

imageLoader = MyApplication.getInstance().getImageLoader();
        imageLoader.get(galleryItem.get_imgPath(), imageLoader.getImageListener(img_thumb,
                R.drawable.ic_launcher,
                android.R.drawable.ic_dialog_alert));
        img_thumb.setImageUrl(galleryItem.get_imgPath(), imageLoader);

LruBitmapCache :

import android.graphics.Bitmap;
import android.support.v4.util.LruCache;

import com.android.volley.toolbox.ImageLoader.ImageCache;

public class LruBitmapCache extends LruCache<String, Bitmap> implements
        ImageCache {
    public static int getDefaultLruCacheSize() {
        final int maxMemory = (int) (Runtime.getRuntime().maxMemory() / 1024);
        final int cacheSize = maxMemory / 8;

        return cacheSize;
    }

    public LruBitmapCache() {
        this(getDefaultLruCacheSize());
    }

    public LruBitmapCache(int sizeInKiloBytes) {
        super(sizeInKiloBytes);
    }

    @Override
    protected int sizeOf(String key, Bitmap value) {
        return value.getRowBytes() * value.getHeight() / 1024;
    }

    @Override
    public Bitmap getBitmap(String url) {
        return get(url);
    }

    @Override
    public void putBitmap(String url, Bitmap bitmap) {
        put(url, bitmap);
    }
}

我的代码有什么问题.我对挣扎感到厌倦.

what's wrong with my code.I'm tired of struggling.

推荐答案

问题似乎是您的图像没有告诉Volley对其进行缓存的缓存标头.您可以通过扩展在MyApplication中初始化的ImageLoader来显式强制缓存.

what seems to be the issue is that your images does not have cache headers that tells Volley to cache it. You can explicitly force the cache by extending your ImageLoader which you initialize in MyApplication.

例如:

mImageLoader = new ImageLoader(this.mRequestQueue,
                new LruBitmapCache()) {
@Override
    protected Request<Bitmap> makeImageRequest(String requestUrl, int maxWidth, int maxHeight,
                ScaleType scaleType, final String cacheKey) {
            return new ImageRequest(requestUrl, new Listener<Bitmap>() {
                @Override
                public void onResponse(Bitmap response) {
                    onGetImageSuccess(cacheKey, response);
                }
            }, maxWidth, maxHeight, scaleType, Config.RGB_565, new ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {
                    onGetImageError(cacheKey, error);
                }
            }){
      @Override
                public Response<Bitmap> parseNetworkResponse(NetworkResponse response) {
                    Response<Bitmap> resp = super.parseNetworkResponse(response);
                    if(!resp.isSuccess()) {
                        return resp;
                    }
                    long now = System.currentTimeMillis();
                    Cache.Entry entry = resp.cacheEntry;
    if(entry == null) {

        entry = new Cache.Entry();
        entry.data = response.data;
        entry.softTtl = now + 1 * 60 * 60 * 1000; // keeps valid(no refresh) for 1hr
        entry.responseHeaders = response.headers;
    }
    entry.ttl = now + 30l * 24 * 60 * 60 * 1000;  //keeps cache for 30 days
                    return Response.success(resp.result, entry);
                }

    };
        }
};

这样，您的图像将在磁盘中缓存30天，但在需要时也会刷新.

This way your images will be cached in the disk for 30 days but also refresh when needed.

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