我正在尝试从 url 获取图像并将其显示到 ListView 项中。 url 是通过 php 从 mysql 数据库中获取的。
目前我无法让图像显示在我的 ListView 项目中。
我正在使用的过程是先下载图像并缓存它，然后将其显示在 ListView 项目上。 (根据我在网上搜索到的内容，我们可以直接获取一个url并将其显示到 ListView 项中)。
任何建议或编码都会很棒。
下面是我正在使用并面临问题的代码。
public void GetProduct () {
class GetJSON extends AsyncTask<Void, Void, String> {
ProgressDialog loading;
@Override
protected void onPreExecute() {
super.onPreExecute();
loading = ProgressDialog.show(getActivity(), "Fetching Data", "Wait...", false, false);
}
@Override
protected void onPostExecute(String s) {
super.onPostExecute(s);
loading.dismiss();
JSON_STRING = s;
JSONObject jsonObject = null;
ArrayList<HashMap<String, String>> list2= new ArrayList<HashMap<String, String>>();
try {
jsonObject = new JSONObject(JSON_STRING);
JSONArray result = jsonObject.getJSONArray(Config.TAG_JSON_ARRAY);
Log.d("JSON", Config.TAG_JSON_ARRAY);
for (int i = 0; i < result.length(); i++) {
JSONObject jo = result.getJSONObject(i);
String id = jo.getString(Config.TAG_ID);
String TITLE = jo.getString(Config.TAG_TITLE);
String BRAND = jo.getString(Config.TAG_BRAND);
String ITEMTYPE = jo.getString(Config.TAG_ITEMTYPE);
String BOOSTERTYPE = jo.getString(Config.TAG_BOOSTERTYPE);
String PRICE = jo.getString(Config.TAG_PRICE);
String IMGURL = jo.getString(Config.TAG_IMGURL);
String QTYINSTOCK = jo.getString(Config.TAG_QTYINSTOCK);
String QTYPENDING = jo.getString(Config.TAG_QTYPENDING);
HashMap<String, String> event = new HashMap<String, String>();
event.put(Config.TAG_ID, id);
event.put(Config.TAG_TITLE, TITLE);
event.put(Config.TAG_BRAND, BRAND);
event.put(Config.TAG_ITEMTYPE, ITEMTYPE);
event.put(Config.TAG_PRICE, PRICE);
event.put(Config.TAG_IMGURL, IMGURL);
event.put(Config.TAG_QTYINSTOCK, QTYINSTOCK);
event.put(Config.TAG_QTYPENDING, QTYPENDING);
//the code i added for picasso
ImageView img = (ImageView)getActivity().findViewById(R.id.iv_flag);
String imgUrl = (String)event.get(Config.TAG_IMGURL);
Picasso.with(getActivity()).load(imgUrl).into(img);
list2.add(event);
ListAdapter adapter = new MyAdapter(
getActivity().getBaseContext(), list2, R.layout.productitem,
new String[]{Config.TAG_TITLE, Config.TAG_PRICE, Config.TAG_BRAND, Config.TAG_ITEMTYPE, Config.TAG_QTYINSTOCK, "flag"},
new int[]{R.id.text1, R.id.text2, R.id.text3, R.id.text4, R.id.text5, R.id.iv_flag});
ProductListing.setAdapter(adapter);
HashMap<String, Object> hm = (HashMap<String, Object>)adapter.getItem(i);
String imgUrl = (String)event.get(Config.TAG_IMGURL);
ImageLoaderTask imageLoaderTask = new ImageLoaderTask();
HashMap<String, Object> hmDownload = new HashMap<String, Object>();
hm.put("flag_path", imgUrl);
hm.put("position",i);
imageLoaderTask.execute(hm);
}
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data [" + e.getMessage() + "] " + jsonObject);
e.printStackTrace();
}
}
@Override
protected String doInBackground(Void... params) {
RequestHandler rh = new RequestHandler();
String s = rh.sendGetRequest("the url for my php file");
return s;
}
}
final GetJSON gj = new GetJSON();
gj.execute();
}
/** 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("flag_path");
Log.d("url1", imgUrl);
int position = (Integer) hm[0].get("position");
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 = getActivity().getBaseContext().getCacheDir();
// Temporary file to store the downloaded image
File tmpFile = new File(cacheDirectory.getPath() + "/wpta_"+position+".png");
// 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("flag",tmpFile.getPath());
// Storing the position of the image in the listview
hmBitmap.put("position",position);
// 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) {
// Getting the path to the downloaded image
String path = (String) result.get("flag");
// Getting the position of the downloaded image
int position = (Integer) result.get("position");
// Getting adapter of the listview
SimpleAdapter adapter = (SimpleAdapter)ProductListing.getAdapter();
// Getting the hashmap object at the specified position of the listview
HashMap<String, Object> hm = (HashMap<String, Object>) adapter.getItem(position);
// Overwriting the existing path in the adapter
hm.put("flag",path);
// Noticing listview about the dataset changes
adapter.notifyDataSetChanged();
}
}
LogCat:
06-11 19:16:21.621 21935-22767/info.androidhive.slidingmenu D/url1: http://www.genesisfrontier.com/cfs/files/images/ib53ZANJkNPJ2cQCS/BFEH_EB2.png
06-11 19:16:21.621 21935-22767/info.androidhive.slidingmenu I/System.out: (HTTPLog)-Static: isSBSettingEnabled false
06-11 19:16:21.631 21935-22767/info.androidhive.slidingmenu I/System.out: KnoxVpnUidStorageknoxVpnSupported API value returned is false
06-11 19:16:21.731 21935-21935/info.androidhive.slidingmenu E/BitmapFactory: Unable to decode stream: java.io.FileNotFoundException: : open failed: ENOENT (No such file or directory)
06-11 19:16:21.731 21935-21935/info.androidhive.slidingmenu I/System.out: resolveUri failed on bad bitmap uri:
下面是 picasso 的 logcat
FATAL EXCEPTION: main
Process: info.androidhive.slidingmenu, PID: 1289
java.lang.IllegalArgumentException: Target must not be null.
at com.squareup.picasso.RequestCreator.into(RequestCreator.java:618)
at com.squareup.picasso.RequestCreator.into(RequestCreator.java:601)
at info.androidhive.slidingmenu.FindPeopleFragment$1GetJSON.onPostExecute(FindPeopleFragment.java:147)
at info.androidhive.slidingmenu.FindPeopleFragment$1GetJSON.onPostExecute(FindPeopleFragment.java:91)
at android.os.AsyncTask.finish(AsyncTask.java:632)
at android.os.AsyncTask.access$600(AsyncTask.java:177)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:5938)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1389)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1184)
最佳答案
使用 Picasso lib 从 Url 下载图片，它会自动从 url 下载图片。要使用 Picasso 库，请将其添加到您的 gradle 文件中
compile 'com.squareup.picasso:picasso:2.5.2'
然后这样做
String imgUrl = (String)event.get(Config.TAG_IMGURL);
Picasso.with(context).load(imgUrl).into("your imageview");
关于php - 无法在 ListView 项中显示图像，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/37763201/