异步加载图像的ListView [英] Load asynchronous images in listView
问题描述
我想从一个服务器加载图片，加载在列表视图中的数据之后。 我知道，很多话题存在这个问题，但我还没有找到解决办法......
I want to load images from a server, AFTER loading the data in a list view. I know that a lot of topics existing for this problem but I haven't found the solution...
所以这是我的code：
So this is my code :
//asyncTackClass for loadingpictures
public class LoadImagesThread extends AsyncTask<Bundle, Void, Bitmap> {
private ImageView view;
private Bitmap bm;
private Context context;
private final WeakReference<ImageView> imageViewReference;
private final String BUNDLE_URL = "url";
private final String BUNDLE_NAME = "name";
private final String BUNDLE_BM = "bm";
public LoadImagesThread(Context context, ImageView view) {
this.context=context;
imageViewReference = new WeakReference<ImageView>(view);
}
@Override
protected Bitmap doInBackground(Bundle... b) {
Bitmap bm =null;
if (StorageHelper.getBitmap(b[0].getString(BUNDLE_NAME)) != null) { // Check the sdcard
bm = StorageHelper.getBitmap(b[0].getString(BUNDLE_NAME));
Log.w("LoadImagesThread", "Get image from sdcard : "+b[0].getString(BUNDLE_NAME));
} else { // Check the server
bm = ServiceHelper.getBitmapFromURL(b[0].getString(BUNDLE_URL));
StorageHelper.saveBitmap(bm, b[0].getString(BUNDLE_NAME)); // Save image on sdcard
Log.w("LoadImagesThread", "Get image from server : "+b[0].getString(BUNDLE_NAME));
}
return bm;
}
@Override
protected void onPostExecute(final Bitmap bm) {
super.onPostExecute(bm);
if (bm != null){ //if bitmap exists...
view = imageViewReference.get();
// Fade out
Animation fadeOutAnimation = AnimationUtils.loadAnimation(context, R.anim.fadeoutimage);
fadeOutAnimation.setAnimationListener(new AnimationListener() {
public void onAnimationStart(Animation animation) {
}
public void onAnimationRepeat(Animation animation) {
}
public void onAnimationEnd(Animation animation) {
// Fade in
view.setImageBitmap(bm);
Animation fadeInAnimation = AnimationUtils.loadAnimation(context, R.anim.fadeinimage);
view.startAnimation(fadeInAnimation);
}
});
// Launch the fadeout
view.startAnimation(fadeOutAnimation);
}else{ //if not picture, display the default ressource
view.setImageResource(R.drawable.productcarre);
}
}
}
在code，以便在ImageView的显示位图
The code is used to display a Bitmap in a ImageView
这是适配器：
public class ListViewShoplistStoresAdapter extends BaseAdapter {
private ArrayList<Shop> shopList;
private Activity activity;
private HashMap<Integer, ImageView> views;
private final String BUNDLE_URL = "url";
private final String BUNDLE_NAME = "name";
private final String BUNDLE_POS = "pos";
private final String BUNDLE_ID = "id";
public ListViewShoplistStoresAdapter(Activity activity, ArrayList<Shop> shopList) {
super();
this.activity = activity;
this.shopList = shopList;
this.views = new HashMap<Integer, ImageView>();
}
public int getCount() {
return shopList.size();
}
public Object getItem(int position) {
return shopList.get(position);
}
public long getItemId(int position) {
return shopList.get(position).getId();
}
private class ViewHolder {
public TextView store;
public TextView name;
public ImageView ImageStore;
}
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder view;
LayoutInflater inflator = activity.getLayoutInflater();
if(convertView == null) {
view = new ViewHolder();
convertView = inflator.inflate(R.layout.listviewshops, null);
view.store = (TextView) convertView.findViewById(R.id.store);
view.name = (TextView) convertView.findViewById(R.id.name);
view.ImageStore = (ImageView) convertView.findViewById(R.id.imgstore);
convertView.setTag(view);
}else {
view = (ViewHolder) convertView.getTag();
}
Typeface regular=Typeface.createFromAsset(activity.getAssets(), "fonts/RobotoRegular.ttf");
view.store.setTypeface(regular);
Typeface light=Typeface.createFromAsset(activity.getAssets(), "fonts/RobotoLight.ttf");
view.store.setTypeface(light);
Brand brand = StorageHelper.getBrand(activity, shopList.get(position).getBrandId());
if (brand == null) {
Log.e("SetShopInAdapter","Brand null");
Toast.makeText(activity, "Impossible d'afficher la liste de magasins", Toast.LENGTH_LONG).show();
} else {
view.store.setText(brand.getName());
view.name.setText(shopList.get(position).getName());
view.ImageStore.setImageResource(R.drawable.productcarre);
}
Bundle b = new Bundle();
//url of the pict
b.putString(BUNDLE_URL, ServiceHelper.getImageUrl("brand", brand.getName()));
// name of image
b.putString(BUNDLE_NAME, ServiceHelper.getCleanImageName(brand.getName()));
//position in the listView
b.putInt(BUNDLE_POS, position);
//id of the current object
b.putInt(BUNDLE_ID, brand.getId());
//put info in the map in order to display in the onPostExecute
if(views.get(position)==null){
views.put(position, view.ImageStore);
// launch thread
new LoadImagesThread(activity.getApplicationContext(), view.ImageStore).execute(b);
}
return convertView;
}
}
所以，当我使用一个GridView，有没有问题，但是当我使用一个ListView的图像仅改变了第一项！
So, when I used a GridView, there were no problems, but when I use a ListView the image is changed only in the first item !
示例： 我想展示的产品图片为汽车，房子和苹果的项目。 在code将启动线程，所有图像（汽车，然后房子，最后苹果）将显示在第一个项目（汽车项目）... 而房子和苹果，而没有图像！
Example: I want to display product images for "car", "house" and "apple" items. The code will launch the thread and all images (car then house and finally apple) will be displayed in the first item (the car item)... And the house and the apple while not have images !!
你知不知道我该怎么办？
Do you know what I should do ?
感谢
推荐答案
您应该参考这个博客。它的真棒。
You should refer to this blog. Its awesome.
<一个href="http://android-developers.blogspot.in/2010/07/multithreading-for-performance.html">http://android-developers.blogspot.in/2010/07/multithreading-for-performance.html
一个演示程序也给出了这个链接。下载软件，并尝试在你的应用程序来实现它。
A demo app is also given on this link . Download that and try to implement it in your app.
这篇关于异步加载图像的ListView的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
