有两项活动:Main
和Detail
活动。
Main Activity
基本上是一个GridView。
Detail Activity
基本上显示了点击项目的详细信息。我将所选项目的ID(pid
)从Main
传递到Detail
活动。
我面临的问题如下。最初,我有3G
连接(手机连接)并点击了第一项,并在Detail Activity
中查看了相应的项目详细信息,它完全正常,然后返回Main Activity
,然后点击第二个项目,然后不幸的是它仍然显示我最初点击的DetailActivity
中的第一个项目。
当应用处于有效状态且已打开时,我从3g
切换到wifi
。无论我点击什么,它仍然显示我最初点击的第一个项目。
但是,当我删除该应用并重新安装并获得wifi
访问 时,该应用就可以正常使用。
在以下实施中,连接网址(PRODUCT_DETAIL_URL)为http
,而非https
。我正在使用Volley
库进行网络连接。
DetailActivity.java
private void productDetailInit() {
// it is http
StringRequest postRequest = new StringRequest(Request.Method.POST, Config.PRODUCT_DETAIL_URL,
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
jsonObject = response;
loadJsonData();
} catch (Exception e) {
e.printStackTrace();
}
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
error.printStackTrace();
}
}
) {
@Override
protected Map<String, String> getParams() {
Map<String, String> params = new HashMap<>();
params.put("id", productID);
return params;
}
};
RetryPolicy policy = new DefaultRetryPolicy(1000, DefaultRetryPolicy.DEFAULT_MAX_RETRIES, DefaultRetryPolicy.DEFAULT_BACKOFF_MULT);
postRequest.setRetryPolicy(policy);
CustomVolleyRequest.getInstance(this).getRequestQueue().add(postRequest);
}
CustomVolleyRequest.java
public class CustomVolleyRequest {
private static CustomVolleyRequest customVolleyRequest;
private static Context context;
private RequestQueue requestQueue;
private ImageLoader imageLoader;
private CustomVolleyRequest(Context context) {
this.context = context;
this.requestQueue = getRequestQueue();
imageLoader = new ImageLoader(requestQueue,
new ImageLoader.ImageCache() {
private final LruCache<String, Bitmap>
cache = new LruCache<String, Bitmap>(20);
@Override
public Bitmap getBitmap(String url) {
return cache.get(url);
}
@Override
public void putBitmap(String url, Bitmap bitmap) {
cache.put(url, bitmap);
}
});
}
private class BitmapCache implements ImageLoader.ImageCache {
private LruCache<String, Bitmap> mCache;
public BitmapCache() {
mCache = new LruCache<>(20);
}
@Override
public Bitmap getBitmap(String url) {
return mCache.get(url);
}
@Override
public void putBitmap(String url, Bitmap bitmap) {
// scaling bitmap for avoiding too much big images
Bitmap scaled = ImageUtil.getInstance().scaleBitmap(bitmap);
mCache.put(url, scaled);
}
}
public static synchronized CustomVolleyRequest getInstance(Context context) {
if (customVolleyRequest == null) {
customVolleyRequest = new CustomVolleyRequest(context);
}
return customVolleyRequest;
}
public RequestQueue getRequestQueue() {
if (requestQueue == null) {
Cache cache = new DiskBasedCache(context.getCacheDir(), 10 * 1024 * 1024);
Network network = new BasicNetwork(new HurlStack());
requestQueue = new RequestQueue(cache, network);
requestQueue.start();
}
return requestQueue;
}
public ImageLoader getImageLoader() {
return imageLoader;
}
}
Adapter.java
class ProductMainAdapter extends ArrayAdapter<ImageRecord> {
private ImageLoader mImageLoader;
private String jsonObject;
ProductMainAdapter(Context context) {
super(context, R.layout.grid_item);
mImageLoader = CustomVolleyRequest.getInstance(this.getContext()).getImageLoader();
}
@NonNull
@Override
public View getView(final int position, View convertView, @NonNull ViewGroup parent) {
final ViewHolder holder;
if(convertView == null) {
holder = new ViewHolder();
convertView = LayoutInflater.from(getContext()).inflate(R.layout.grid_item, parent, false);
convertView.setBackgroundResource(R.drawable.round_gridview);
holder.priceTagImage = (ImageView) convertView.findViewById(R.id.priceTag_IV);
holder.textView = (TextView) convertView.findViewById(R.id.text);
holder.imageView = (NetworkImageView) convertView.findViewById(R.id.picture);
holder.priceTagRL = (RelativeLayout) convertView.findViewById(R.id.priceTag_RL);
convertView.setTag(holder);
}
else {
holder = (ViewHolder) convertView.getTag();
}
ImageRecord imageRecord = getItem(position);
holder.imageView.setImageUrl(imageRecord != null ? imageRecord.getUrl() : null, mImageLoader);
holder.imageView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
openProductDetail(position);
}
});
holder.textView.setText(imageRecord != null ? imageRecord.getTitle() : null);
holder.priceTagRL.setRotation(0);
return convertView;
}
private class ViewHolder{
TextView textView;
ImageView priceTagImage;
NetworkImageView imageView;
RelativeLayout priceTagRL;
}
private void openProductDetail(int position) {
try {
ImageRecord imr = getItem(position);
String productID = imr != null ? imr.getId() : "0";
Intent intent = new Intent(getContext(), ProductDetailActivity.class);
intent.putExtra("pid", productID);
getContext().startActivity(intent);
} catch (Exception e) {
Log.e("openProductDetail", "exception", e);
}
}