首先,我已经做了很少的事情来在gridview中显示图像,使滚动时变得平滑
1.从背景线程上的互联网加载图像
AsyncTask acyncTask ;
HandlerThread handlerThread ;
URL imageUrl = new URL(link);2.将位图设置为样本大小以节省内存
final BitmapFactory.Options option = new BitmapFactory.Options();
option.inJustDecodeBounds = true;
BitmapFactory.decodeFile(mFile.getPath(),option);
option.inSampleSize = calculateInSampleSize(option,mSize,mSize);
option.inJustDecodeBounds = false;
option.inPurgeable = true ;
option.inDither = false ;
option.inScaled = false ;
option.inPreferredConfig = Bitmap.Config.ARGB_8888;
3.制作缓存以保存解码的位图
LruCache lruCache = new LruCache在baseadapter getView();
我将lruCache.get(key)取得解码后的位图
4.通过处理程序解码位图时的延迟加载
Handler handler = new Handler();
handler.post(new Runnable(){
public void run(){
imageView.setimageBitmap(bitmap);
}
});
现在我面临一个大问题,当我滚动时它仍然有点滞后
我有谷歌的东西可以使滚动更好,不知道真的有什么可以改善或问题出来的地方我检查每个getView()只花我约2~6毫秒它会调用我的代码异步加载图像表单工作线程,所以我真的不知道为什么有些应用程序可以加载非常流畅？我的情况是当滚动屏幕看起来不是很顺利是否有一些建议可以适用？
编辑：当我滚动时,在缓存中找到位图并在屏幕上显示,如果我快速滚动,它看起来就像没有滚动到足以显示图像,它会使我的滚动不那么顺利,即使我有缓存下来缓存中的位图
这是适配器代码：
if (convertView == null) {
convertView = layoutInflater.inflate(
R.layout.row_display_image_grid,null);
viewHolder = new displayImageGridViewHolder();
viewHolder.background = (RelativeLayout) convertView
.findViewById(R.id.background);
viewHolder.image = (ImageView) convertView.findViewById(R.id.image);
viewHolder.text = (TextView) convertView.findViewById(R.id.text);
viewHolder.position = position;
viewHolder.text.setEllipsize(TruncateAt.END);
viewHolder.text.setTypeface(typeFace);
viewHolder.image.setonClickListener(this);
viewHolder.image.setonLongClickListener(this);
convertView.setTag(viewHolder);
} else {
viewHolder = (displayImageGridViewHolder) convertView.getTag();
}
viewHolder.position = position;
imageLoader.loadImage(imageLinkList.get(position),viewHolder.image);
return convertView;
最佳答案
下面是我使用的LazyLoader的示例.注意我使用SoftReferences作为位图,现在使用LruCache可以更好地服务.
这将从web / sdcard / memory异步加载图像,并从占位符图像创建淡入效果.
public class ImageLoader {
private static MemoryCacheNew memoryCache=new MemoryCacheNew();
private static FileCache fileCache;
private static BitmapFactory.Options bitmapOptions;
private static int mInSampleSize;
public ImageLoader(Context context,int inSampleSize){
fileCache=new FileCache(context);
context = null;
bitmapOptions = new BitmapFactory.Options();
bitmapOptions.inSampleSize = mInSampleSize = inSampleSize;
bitmapOptions.inPreferredConfig = Config.RGB_565;
bitmapOptions.inInputShareable = true;
bitmapOptions.inDither = false;
}
final static int PLACEHOLDER_IMAGE = R.drawable.store_placeholder;
public void displayImage(String url,ImageView imageView,boolean checkTags){
try{
new AsyncPhotoTask(imageView,url,checkTags).execute();
}catch(Exception e){
e.printstacktrace();
}
}
public void displayImage(String url,ImageView imageView)
{
displayImage(url,imageView,true);
}
private static Bitmap getBitmap(String url)
{
File f=fileCache.getFile(url);
if(f!= null){
//from SD cache
Bitmap b = decodeFile(f);
if(b!=null)
return b;
}
//from web
try {
Bitmap bitmap=null;
URL imageUrl;
imageUrl = new URL(url);
HttpURLConnection conn = (HttpURLConnection)imageUrl.openConnection();
conn.setConnectTimeout(30000);
conn.setReadTimeout(30000);
InputStream is=conn.getInputStream();
OutputStream os = new FileOutputStream(f);
Utils.copyStream(is,os);
is.close();
os.close();
bitmap = decodeFile(f);
return bitmap;
} catch (Exception ex){
ex.printstacktrace();
return null;
}
}
//decodes image and scales it to reduce memory consumption
private static Bitmap decodeFile(File f){
try {
return BitmapFactory.decodeStream(new FileInputStream(f),null,bitmapOptions);
} catch (FileNotFoundException e) {
} catch (OutOfMemoryError err){
System.gc();
}
return null;
}
private static class AsyncPhotoLoad extends AsyncTaskprintstacktrace();
}
return transition;
}
@Override
protected void onPostExecute(TransitionDrawable result) {
if(result != null){
try{
if(checkTags){
String tag = (String)imageView.getTag();
if(!tag.equals(url)){
return;
}
}
imageView.setimageDrawable(result);
result.startTransition(300);
} catch(Exception e){
e.printstacktrace();
}
} else {
if(checkTags){
try{
String tag = (String)imageView.getTag();
if(!tag.equals(url))
return;
}catch(Exception e){
e.printstacktrace();
}
}
}
}
}
private static class AsyncPhotoTask extends AsyncTaskarams) {
try{
if(checkTags)
imageView.setTag(url);
}catch(Exception e){
e.printstacktrace();
}
return memoryCache.get(url,mInSampleSize);
}
@Override
protected void onPostExecute(Bitmap result) {
try{
if(result!=null && !result.isRecycled()){
imageView.setimageBitmap(result);
}
else
{
imageView.setimageResource(PLACEHOLDER_IMAGE);
new AsyncPhotoLoad(imageView,checkTags).execute();
}
}catch(Exception e){
e.printstacktrace();
}
}
}
public static void clearCache() {
memoryCache.clear();
fileCache.clear();
}
public static void clearMemory(){
memoryCache.clear();
}
public static class MemoryCacheNew {
private HashMap.softBitmap;
return ref.get();
}
public void put(String id,Bitmap bitmap,int sampleSize){
cache.put(id,new CachedBitmap(bitmap,sampleSize));
}
public void clear() {
cache.clear();
}
private static class CachedBitmap {
public SoftReference.softBitmap = new SoftReferenceirs();
}
public File getFile(String url){
//I identify images by hashcode. Not a perfect solution,good for the demo.
String filename=String.valueOf(url.hashCode());
File f = new File(cacheDir,filename);
return f;
}
public void clear(){
File[] files=cacheDir.listFiles();
for(File f:files)
f.delete();
}
}
你这样称呼它：
imageLoader.displayImage(url,holder.image);
原文地址：https://www.jb51.cc/android/430594.html
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