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