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我想做一個列表視圖。我沒有使用自定義陣列適配器從url加載照片，但成功地完成了它。但是，我怎麼能實現從URL加載圖像，而無需使用自定義數組適配器？從URL加載圖像到ListView
我想使用這個thread的工作代碼，但它給持有者發生錯誤。
誤差部分
icon = new ImageDownloaderTask(holder.imageView).execute(doctorPhoto);
DoctorsActivity.java
public class DoctorsActivity extends AppCompatActivity {
private JSONArray arrayAdapter;
private static final String URL_FOR_BALANCE = "http://192.168.1.28/api2/doctors.php";
String cancel_req_tag = "login";
private ListView lv;
ArrayList<HashMap<String, String>> contactList;
Bitmap icon = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_doctors);
getSupportActionBar().setDisplayOptions(ActionBar.DISPLAY_SHOW_CUSTOM);
getSupportActionBar().setCustomView(R.layout.toolbar_doctors);
getSupportActionBar().setBackgroundDrawable(new ColorDrawable(Color.parseColor("#003764")));
getSupportActionBar().setDisplayHomeAsUpEnabled(false);
SharedPreferences sharedPreferences = getSharedPreferences(Config.SHARED_PREF_NAME, Context.MODE_PRIVATE);
final String pid = sharedPreferences.getString(Config.UID_SHARED_PREF, null);
contactList = new ArrayList<>();
lv = (ListView) findViewById(R.id.list);
StringRequest strReq = new StringRequest(Request.Method.POST,
URL_FOR_BALANCE, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
try {
JSONObject jObj = new JSONObject(response);
boolean error = jObj.getBoolean("error");
if (!error) {
JSONArray contacts = jObj.getJSONArray("user");
for (int i = 0; i < contacts.length(); i++) {
JSONObject c = contacts.getJSONObject(i);
String doctorTitle = c.getString("title");
String doctorName = c.getString("first_name");
String doctorSurname = c.getString("last_name");
String doctorPhoto = c.getString("photo"); //image URL
String doctorMobile = c.getString("mobile");
String doctorFullName = doctorTitle+" "+doctorName+" "+doctorSurname;
icon = new ImageDownloaderTask(holder.imageView).execute(doctorPhoto);
// tmp hash map for single contact
HashMap<String, String> contact = new HashMap<>();
// adding each child node to HashMap key => value
contact.put("photo", icon);
contact.put("doctor", doctorFullName);
contact.put("mobile", doctorMobile);
// adding contact to contact list
contactList.add(contact);
}
ListAdapter adapter = new SimpleAdapter(
DoctorsActivity.this, contactList,
R.layout.activity_doctors_list_item, new String[]{"photo", "doctor",
"mobile"}, new int[]{R.id.photo,
R.id.doctor, R.id.mobile});
lv.setAdapter(adapter);
} else {
String errorMsg = jObj.getString("error_msg");
Toast.makeText(getApplicationContext(),
errorMsg, Toast.LENGTH_LONG).show();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Toast.makeText(getApplicationContext(),
error.getMessage(), Toast.LENGTH_LONG).show();
}
}) {
@Override
protected Map<String, String> getParams() {
// Posting params to login url
Map<String, String> params = new HashMap<String, String>();
params.put("uid", pid);
params.put("lang", Locale.getDefault().getDisplayLanguage());
return params;
}
};
// Adding request to request queue
AppSingleton.getInstance(getApplicationContext()).addToRequestQueue(strReq,cancel_req_tag);
}
class ImageDownloaderTask extends AsyncTask<String, Void, Bitmap> {
private final WeakReference<ImageView> imageViewReference;
public ImageDownloaderTask(ImageView imageView) {
imageViewReference = new WeakReference<ImageView>(imageView);
}
@Override
protected Bitmap doInBackground(String... params) {
return downloadBitmap(params[0]);
}
@Override
protected void onPostExecute(Bitmap bitmap) {
if (isCancelled()) {
bitmap = null;
}
if (imageViewReference != null) {
ImageView imageView = imageViewReference.get();
if (imageView != null) {
if (bitmap != null) {
imageView.setImageBitmap(bitmap);
} else {
Drawable placeholder = null;
imageView.setImageDrawable(placeholder);
}
}
}
}
private Bitmap downloadBitmap(String url) {
HttpURLConnection urlConnection = null;
try {
URL uri = new URL(url);
urlConnection = (HttpURLConnection) uri.openConnection();
final int responseCode = urlConnection.getResponseCode();
if (responseCode != HttpURLConnection.HTTP_OK) {
return null;
}
InputStream inputStream = urlConnection.getInputStream();
if (inputStream != null) {
Bitmap bitmap = BitmapFactory.decodeStream(inputStream);
return bitmap;
}
} catch (Exception e) {
urlConnection.disconnect();
Log.w("ImageDownloader", "Errore durante il download da " + url);
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
}
return null;
}
}
}