我正在尝试在使用Simple Adapter创建的listView的相应ImageView中显示图像。到目前为止，图像正在下载到磁盘上的某个位置，文本数据在listView中显示正常，但我无法将下载的图像显示到listView项目的正确位置。到目前为止，我的代码看起来像这样......
public class MainActivity extends ListActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// More Code Here
...
productList = new ArrayList<HashMap<String, Object>>();
this.getListView().setOnScrollListener(new EndlessScrollListener() {
@Override
public void onLoadMore(int page, int totalItemsCount) {
// Triggered only when new data needs to be appended to the list
// Add whatever code is needed to append new items to your
// AdapterView
customLoadMoreDataFromApi(page);
// or customLoadMoreDataFromApi(totalItemsCount);
}
});
addInitialLoader();
addKeyListener();
// Get listview
lv = getListView();
}
// Append more data into the adapter
public void customLoadMoreDataFromApi(int offset) {
// This method probably sends out a network request and appends new data items to your adapter.
// Use the offset value and add it as a parameter to your API request to retrieve paginated data.
// Deserialize API response and then construct new objects to append to the adapter
//Toast.makeText(MainActivity.this,
//"...loading more items" + offset + "...",
//Toast.LENGTH_LONG).show();
final Toast tost2 = Toast.makeText(MainActivity.this,
"...loading more items" + offset + "...",
Toast.LENGTH_LONG);
tost2.show();
Handler handler2 = new Handler();
handler2.postDelayed(new Runnable() {
@Override
public void run() {
tost2.cancel();
}
}, 1000);
}
public void addInitialLoader() {
// get Internet status
isInternetPresent = cd.isConnectingToInternet();
// check for Internet status
if (isInternetPresent) {
// Internet Connection is Present
// make HTTP requests
new JSONParse().execute();
return;
} else {
// Internet connection is not present
// Ask user to connect to Internet
showAlertDialog(MainActivity.this,
"No Internet Connection",
"You don't have internet connection.", false);
}
}
private class JSONParse extends AsyncTask<String, String, JSONObject> {
private ProgressDialog pDialog;
@Override
protected void onPreExecute() {
super.onPreExecute();
// Some code Here
...
}
@Override
protected JSONObject doInBackground(String... args) {
JSONParser jParser = new JSONParser();
// Clear previous list items
productList.clear();
// Getting JSON from URL
JSONObject json = jParser.makeHttpRequest(url,
"GET", params);
if (json != null) {
try {
// Getting JSON Array
Iterator<String> keys = json.keys();
while (keys.hasNext()) {
String key = keys.next();
String pid = "";
String img = "";
String weight = "";
String name = "";
String desciption = "";
String price = "";
int maxLen = 15;
int maxLen2 = 20;
JSONObject c = json.getJSONObject(key);
String err = c.getString(TAG_ERROR) == "false" ? "" : "true";
if (err == "true") {
pid = "0";
img = "0";
weight = "0";
name = "None";
desciption = "none";
price = "none";
} else {
pid = c.getString(TAG_PID);
img = c.getString(TAG_IMAG);
weight = c.getString(TAG_SIZE);
name = c.getString(TAG_NAME);
desciption = c.getString(TAG_DESCR);
price = c.getString(TAG_PRICE);
}
// tmp hashmap for single contact
HashMap<String, Object> cartitem = new HashMap<String, Object>();
// adding each child node to HashMap key => value
cartitem.put(TAG_PID, pid);
cartitem.put(TAG_IMAG, R.drawable.logo);
cartitem.put(TAG_IMP, img);
cartitem.put(TAG_SIZE, "Size: " + qty);
cartitem.put(TAG_NAME, name);
cartitem.put(TAG_DESCR, desciption);
cartitem.put(TAG_SIZE, weight);
if (err == "") {
cartitem.put(TAG_PRICE, price);
} else {
cartitem.put(TAG_PRICE,
"Error: No cart to show or items are already delivered.");
}
// adding product details to product list
productList.add(cartitem);
}
} catch (JSONException e) {
Log.e("ERROR Exception: ", e.toString());
e.printStackTrace();
}
} else {
// Internet connection is not present
Log.e("ERROR Json: ", "No Internet Available");
}
return null;
}
@Override
protected void onPostExecute(JSONObject json) {
// protected void onPostExecute(Void result) {
super.onPostExecute(json);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
// Keys used in Hashmap
String[] from = { TAG_SIZE, TAG_NAME, TAG_DESCR, TAG_PRICE, TAG_PID };
// Ids of views in listview_layout
int[] to = { R.id.size, R.id.name, R.id.descr, R.id.price, R.id.pid };
ListAdapter adapter = new SimpleAdapter(MainActivity.this,
productList, R.layout.list_item, from, to);
setListAdapter(adapter);
//Log.i("Adapter Count:", ""+adapter.getCount());
for(int i=0;i<adapter.getCount();i++){
HashMap<String, Object> hm = (HashMap<String, Object>) adapter.getItem(i);
String imgUrl = (String) hm.get(TAG_IMP);
ImageLoaderTask imageLoaderTask = new ImageLoaderTask();
// HashMap<String, Object> hmDownload = new HashMap<String, Object>();
// Only put images that are set
String needle = "img/nophoto.png";
if(!needle.equals(imgUrl)) {
hm.put("img_path", imgUrl);
hm.put("position", i);
Log.i("HM:", hm.toString());
imageLoaderTask.execute(hm);
}
// Starting ImageLoaderTask to download and populate image in the listview
}
}
}
}
/** AsyncTask to download and load an image in ListView */
private class ImageLoaderTask extends AsyncTask<HashMap<String, Object>, Void, HashMap<String, Object>>{
@Override
protected HashMap<String, Object> doInBackground(HashMap<String, Object>... hm) {
InputStream iStream=null;
String imgUrl = (String) hm[0].get("img_path");
//imgUrl = imgUrl.replace("\\/", "");
imgUrl = imgrl + imgUrl;
int position = (Integer) hm[0].get("position");
Log.i("IMGURL:", imgUrl);
URL url;
try {
url = new URL(imgUrl);
// Creating an http connection to communicate with url
HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
// Connecting to url
urlConnection.connect();
// Reading data from url
iStream = urlConnection.getInputStream();
// Getting Caching directory
File cacheDirectory = Environment.getExternalStorageDirectory(); //getBaseContext().getCacheDir();
if (cacheDirectory.canWrite()){
File dir = new File (cacheDirectory.getAbsolutePath() + "/IMGDir");
dir.mkdirs();
// Temporary file to store the downloaded image
File tmpFile = new File(dir, "/myimg_"+position+".png");
Log.i("Temp:", cacheDirectory.getAbsolutePath());
// The FileOutputStream to the temporary file
FileOutputStream fOutStream = new FileOutputStream(tmpFile);
// Creating a bitmap from the downloaded inputstream
Bitmap b = BitmapFactory.decodeStream(iStream);
// Writing the bitmap to the temporary file as png file
b.compress(Bitmap.CompressFormat.PNG,100, fOutStream);
// Flush the FileOutputStream
fOutStream.flush();
//Close the FileOutputStream
fOutStream.close();
// Create a hashmap object to store image path and its position in the listview
HashMap<String, Object> hmBitmap = new HashMap<String, Object>();
// Storing the path to the temporary image file
hmBitmap.put("img",tmpFile.getPath());
// Storing the position of the image in the listview
hmBitmap.put("position",position);
Log.i("HMB:", hmBitmap.toString());
// Returning the HashMap object containing the image path and position
return hmBitmap;
}
}catch (Exception e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(HashMap<String, Object> result) {
if(result != null) {
// Getting the path to the downloaded image
String path = (String) result.get("img");
// Getting the position of the downloaded image
int position = (Integer) result.get("position");
// Get listview
//lv = getListView();
// Getting adapter of the listview
SimpleAdapter adapter = (SimpleAdapter) lv.getAdapter();
// Getting the hashmap object at the specified position of the listview
HashMap<String, Object> hm = (HashMap<String, Object>) adapter.getItem(position);
Log.i("POS:", adapter.getItem(position).toString());
// Overwriting the existing path in the adapter
hm.put("image",path);
Log.i("POS 2:", adapter.getItem(position).toString());
// Noticing listview about the dataset changes
//setListAdapter(adapter);
adapter.notifyDataSetChanged();
}
}
}
}
我很感激找到连接的任何帮助
提前谢谢
答案 0 :(得分：0)
SimpleAdapter没有能力滚动更多＆＃34;您正在尝试动态更新。来自文档：
一个简单的适配器，用于将静态数据映射到XML文件中定义的视图。
在您传递数据地图列表后，SimpleAdapter无法注意到您已更新该列表。
此外，为了有效地显示静态数据的图像，您需要使用覆盖setViewImage的子类或定义可以映射图像的ViewBinder并调用adapter.setViewBinder以便适配器知道如何将图像绑定到您的数据。
要实现您要执行的操作，您需要创建BaseAdapter的子类，以便您可以动态添加数据并将图像正确绑定到ImageView。