异步图片加载、内存、磁盘缓存 - JAVA

leInputStream(f); return Drawable.createFromStream(fis, "src"); } // 远程加载图片后写入到 SD 卡上 InputStream i = this.getImageInputStream(imageUrl); if (i == null) { return null; } final Drawable drawable = Drawable.createFromStream(i, "src"); if (drawable == null) { return null; } // 将图片异步写入到本地 SD 卡中缓存, 避免阻塞UI线程, 导致图片不能显示 new Thread(new Runnable() { @Override public void run() { ZLog.i(TAG, "async write image file disk cache"); try { BitmapDrawable bd = (BitmapDrawable) drawable; Bitmap bitmap = bd.getBitmap(); FileOutputStream out = new FileOutputStream(f); bitmap.compress(Bitmap.CompressFormat.JPEG, 90, out); out.close(); } catch (IOException e) { ZLog.e(TAG, "write image cache IOException: "+ e.getMessage()); AppException.io(e); } } }).start(); return drawable; } // 只读取远程图片不缓存 else { InputStream i = this.getImageInputStream(imageUrl); if (i == null) { return null; } return Drawable.createFromStream(i, "src"); } } /** * 远程加载图片数据 * * @param imageUrl * @return * @throws java.io.IOException */ public InputStream getImageInputStream(String imageUrl) throws IOException { ZLog.i(TAG, "load image from url"); if (! ZConnectivity.isNetworkConnected()) { ZLog.i(TAG, "net work not connected"); return null; } URL m = new URL(imageUrl); HttpURLConnection conn = (HttpURLConnection) m.openConnection(); conn.setRequestMethod("GET"); conn.setUseCaches(false); conn.setDoInput(true); conn.setConnectTimeout(5000); conn.setReadTimeout(30000); conn.setInstanceFollowRedirects(true); return conn.getInputStream(); } /** * 加载图片的事件监听器 */ public interface OnImageLoadListener { /** * 图片加载完成事件处理 * * @param imageDrawable * @param imageUrl * @param tag */ public void onSuccess(Drawable imageDrawable, String imageUrl, String tag); /** * 图片加载失败的事件处理 * * @param e * @param imageUrl * @param tag */ public void onFailure(IOException e, String imageUrl, String tag); } }

使用方法：

    /**
     * 日记照片加载事件监听
     */
    private class OnPicLoadListener extends OnImageLoadListener
    {
        private int mImageSource = R.drawable.default_pic;

        /**
         * 设置图片
         *
         * @param view
         * @param imageUrl
         * @param tag
         * @param drawable
         */
        public void setDrawable(ImageView view, String imageUrl, String tag, Drawable drawable)
        {
            if (view == null) return;
            int height = 0;
            if (mImagesHeight.containsKey(imageUrl)) {
                height = mImagesHeight.get(imageUrl);
            }
            View ct = ((View) view.getParent()).findViewById(R.id.calendarCt);
            if (ct != null) {
                ct.setVisibility(View.INVISIBLE);
            }
            if (drawable != null) {
                // 定义图片的最佳高度
                if (height == 0) {
                    int minHeight = ZUI.dp2px(mContext, PIC_MIN_HEIGHT);
                    int maxHeight = ZUI.dp2px(mContext, PIC_MAX_HEIGHT);
                    height = (int) ((float) view.getWidth() / drawable.getMinimumWidth() * drawable.getMinimumHeight());
                    if (height > maxHeight) {
                        height = maxHeight;
                    } else if (height < minHeight) {
                        height = minHeight;
                    }
                    mImagesHeight.put(imageUrl, height);
                }
                // 现将图片完全透明
                drawable.setAlpha(0);
                view.setLayoutParams(new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, height));
                view.setScaleType(ImageView.ScaleType.CENTER_CROP);
                view.setImageDrawable(drawable);
                // 添加透明渐变动画显示图片
                AlphaAnimation alphaAnim = new AlphaAnimation(0.0f, 1.0f);
                alphaAnim.setDuration(100);
                view.setAnimation(alphaAnim);
                if (ct != null) {
                    ct.setVisibility(View.VISIBLE);
                }
            } else {
                int minHeight = ZUI.dp2px(mContext, PIC_MIN_HEIGHT);
                height = height < minHeight   minHeight : height;
                view.setLayoutParams(new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, height));
                view.setScaleType(ImageView.ScaleType.CENTER);
                view.setImageResource(mImageSource);
            }
        }
    }

    /**
     * 图片的加载监听事件
     */
    abstract private class OnImageLoadListener implements ZImageLoader.OnImageLoadListener
    {
        /**
         * 实现图片显示的抽象方法
         *
         * @param view
         * @param tag
         * @param drawable
         */
        abstract public void setDrawable(ImageView view, String imageUrl, String tag, Drawable drawable);

        @Override
        public void onSuccess(Drawable drawable, String imageUrl, String tag) {
            ImageView view = (ImageView) mDiaryListView.findViewWithTag(tag == null   imageUrl : tag);
            this.setDrawable(view, imageUrl, tag, drawable);
        }

        @Override
        public void onFailure(IOException e, String imageUrl, String tag) {
            //Toast.makeText(mContext, e.toString(), Toast.LENGTH_SHORT).show();
        }
    }

// 调用该方法
ZImageLoader.getInstance().loadDrawable(item.getPicUrl(), item.getPicTag(), this.mOnPicLoadListener);

这是之前自己实现的简单的图片加载缓存类，不过今天开始尝试使用开源的《Android Universal Image Loader》，先把代码贴在这儿也算做个备份吧

github项目地址：https://github.com/nostra13/Android-Universal-Image-Loader

功能很完善、很强大了

异步图片加载、内存、磁盘缓存(二)