android - 从url下载图像并将其实现到android中的 ListView

Question

我试图在 ListView 中显示来自不同 url 的图像，我从 jsonarray 接收我的 url 和其他详细信息，我从 graph api 获取这些信息，我从中将数据解析为列表并在中显示详细信息listview 但那个 jsonobject 给了我图像文件的 url，我想我需要先下载并显示而不是通过延迟加载，我正在按照本教程进行延迟加载- http://wptrafficanalyzer.in/blog/android-lazy-loading-images-and-text-in-listview-from-http-json-data/ .我在一个 fragment 类中实现，在运行应用程序时它就停止工作了。我将非常感谢所提供的任何帮助。

这是我的代码

Request request1 = new Request(session,"/fql",params,HttpMethod.GET,new Request.Callback()
            {
                public void onCompleted(Response response)
                {

                    int indexex=nthOccurrence(response.getGraphObject().toString(),'{',1);
                    int index=response.getGraphObject().toString().length()-1;
                    String edit=response.getGraphObject().toString().substring(indexex, index);
                    try
                    {
                        JSONObject json = Util.parseJson(edit);
                        JSONArray data = json.getJSONArray( "data" );
                        JSONObject getVideo = data.getJSONObject(2);
                        String s="{data:"+getVideo.getString("fql_result_set")+"}";
                        JSONObject json1 = Util.parseJson(s);
                        JSONArray data1 = json1.getJSONArray("data");
                        ListViewLoaderTask listViewLoaderTask = new ListViewLoaderTask();
                        listViewLoaderTask.execute(data1);
}
                    catch(Exception e){
                        userNameView.setText(e.toString());
                    }   
                }                  
            });
            Request.executeBatchAsync(request1); 

private class DisplayDetails extends AsyncTask<Session, Void, JSONArray>
    {
        Session session;
        Request request1;
        @Override
        protected JSONArray doInBackground(Session...sessions) 
        {
            session=sessions[0];
            Request request = Request.newMeRequest(session, new Request.GraphUserCallback() 
            {
                @Override
                public void onCompleted(GraphUser user, Response response) 
                {
                  if (user != null) 
                  {
                      profilePictureView.setProfileId(user.getId());
                      // Set the Textview's text to the user's name
                      userNameView.setText(user.getName());
                  }
                }
              });
            Request.executeBatchAsync(request);
            String fqlQuery = "{'myVideos':'SELECT vid, src, owner, title, description,thumbnail_link, created_time FROM video WHERE owner=me()'," +
                    "'friends':'SELECT uid2 FROM friend WHERE uid1 = me()',"+
                    "'friendsVideo':'SELECT vid, src, owner, title, description,thumbnail_link, created_time FROM video WHERE owner IN "+
                    "(SELECT uid2 FROM #friends) ORDER BY created_time',}";

            Bundle params = new Bundle();

            params.putString("q", fqlQuery);

            Session session1 = Session.getActiveSession();
            request1 = new Request(session,"/fql",params,HttpMethod.GET,new Request.Callback()
            {
                public void onCompleted(Response response)
                {

                    int indexex=nthOccurrence(response.getGraphObject().toString(),'{',1);
                    int index=response.getGraphObject().toString().length()-1;
                    String edit=response.getGraphObject().toString().substring(indexex, index);
                    try
                    {
                        JSONObject json = Util.parseJson(edit);
                        JSONArray data = json.getJSONArray( "data" );
                        String fbGraph;
                        JSONObject getVideo = data.getJSONObject(2);
                        String s="{data:"+getVideo.getString("fql_result_set")+"}";
                        JSONObject json1 = Util.parseJson(s);
                        data1 = json1.getJSONArray("data");
                    }
                    catch(Exception e){}

                }
            });
            return data1;
        }

        @Override
        protected void onPostExecute(JSONArray data1) 
        {
            ListViewLoaderTask listViewLoaderTask = new ListViewLoaderTask();
            listViewLoaderTask.execute(data1);
            Request.executeBatchAsync(request1);
        }

    }

    private class ListViewLoaderTask extends AsyncTask<JSONArray, Void, SimpleAdapter>
    {

        JSONObject getVidDetails;
        // Doing the parsing of xml data in a non-ui thread
        @Override
        protected SimpleAdapter doInBackground(JSONArray... data) 
        {
            HashMap<String, Object> hm = new HashMap<String,Object>();
            List<HashMap<String, Object>> videoDetails = null;
            userNameView.setText("dsrf");
            try{
                for ( int i = 0, size = data1.length(); i < size; i++ )
                {                   
                    getVidDetails=data[0].getJSONObject(i);
                    hm.put("title", "Title : " + getVidDetails.getString("title") );
                    DateFormat formatter = new SimpleDateFormat("dd/MM/yyyy");
                    hm.put("creationDate","Created On : " + formatter.format(Long.valueOf(getVidDetails.getString("created_time")).longValue()*1000));
                    hm.put("videoThumbnail", R.drawable.blank);
                    hm.put("thumbnail_path",getVidDetails.getString("thumbnail_link"));
                    hm.put("owner","Owner : " +getVidDetails.getString("owner") );
                    videoDetails.add(hm);
                }

            }catch(Exception e){
                Log.d("JSON Exception1",e.toString());
            }

            String[] itemControl = {"videoThumbnail","title","creationDate","owner"};
            int[] itemLayout={R.id.videoThumb,R.id.title,R.id.creationDate,R.id.owner};
            SimpleAdapter adapter = new SimpleAdapter(getActivity().getBaseContext(), videoDetails, R.layout.listvideos_layout, itemControl, itemLayout);

            return adapter;
        }

        *//** Invoked by the Android on "doInBackground" is executed *//*
        @Override
        protected void onPostExecute(SimpleAdapter adapter) 
        {

            // Setting adapter for the listview
            listView.setAdapter(adapter);

            for(int i=0;i<adapter.getCount();i++){
                HashMap<String, Object> hm = (HashMap<String, Object>) adapter.getItem(i);
                String imgUrl = (String) hm.get("thumbnail_path");
                ImageLoaderTask imageLoaderTask = new ImageLoaderTask();

                HashMap<String, Object> hmDownload = new HashMap<String, Object>();
                hm.put("thumbnail_path",imgUrl);
                hm.put("position", i);

                // Starting ImageLoaderTask to download and populate image in the listview
                imageLoaderTask.execute(hm);
            }
        }
    }

    *//** 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("thumbnail_path");
            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+".jpg");

                // 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 jpg file
                b.compress(Bitmap.CompressFormat.JPEG,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("videoThumbnail",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("videoThumbnail");

            // Getting the position of the downloaded image
            int position = (Integer) result.get("position");

            // Getting adapter of the listview
            SimpleAdapter adapter = (SimpleAdapter ) listView.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("videoThumbnail",path);

            // Noticing listview about the dataset changes
            adapter.notifyDataSetChanged();
        }
    }

我还添加了我的应用程序的日志 cat 文件-

12-22 16:08:41.371: W/dalvikvm(625): threadid=11: thread exiting with uncaught exception (group=0x409c01f8)
12-22 16:08:42.120: E/AndroidRuntime(625): FATAL EXCEPTION: AsyncTask #1
12-22 16:08:42.120: E/AndroidRuntime(625): java.lang.RuntimeException: An error occured while executing doInBackground()
12-22 16:08:42.120: E/AndroidRuntime(625):  at android.os.AsyncTask$3.done(AsyncTask.java:278)
12-22 16:08:42.120: E/AndroidRuntime(625):  at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
12-22 16:08:42.120: E/AndroidRuntime(625):  at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
12-22 16:08:42.120: E/AndroidRuntime(625):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
12-22 16:08:42.120: E/AndroidRuntime(625):  at java.util.concurrent.FutureTask.run(FutureTask.java:137)
12-22 16:08:42.120: E/AndroidRuntime(625):  at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
12-22 16:08:42.120: E/AndroidRuntime(625):  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
12-22 16:08:42.120: E/AndroidRuntime(625):  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
12-22 16:08:42.120: E/AndroidRuntime(625):  at java.lang.Thread.run(Thread.java:856)
12-22 16:08:42.120: E/AndroidRuntime(625): Caused by: android.view.ViewRootImpl$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.
12-22 16:08:42.120: E/AndroidRuntime(625):  at android.view.ViewRootImpl.checkThread(ViewRootImpl.java:4039)
12-22 16:08:42.120: E/AndroidRuntime(625):  at android.view.ViewRootImpl.requestLayout(ViewRootImpl.java:709)
12-22 16:08:42.120: E/AndroidRuntime(625):  at android.view.View.requestLayout(View.java:12675)
12-22 16:08:42.120: E/AndroidRuntime(625):  at android.view.View.requestLayout(View.java:12675)
12-22 16:08:42.120: E/AndroidRuntime(625):  at android.view.View.requestLayout(View.java:12675)
12-22 16:08:42.120: E/AndroidRuntime(625):  at android.view.View.requestLayout(View.java:12675)
12-22 16:08:42.120: E/AndroidRuntime(625):  at android.view.View.requestLayout(View.java:12675)
12-22 16:08:42.120: E/AndroidRuntime(625):  at android.view.View.requestLayout(View.java:12675)
12-22 16:08:42.120: E/AndroidRuntime(625):  at android.widget.RelativeLayout.requestLayout(RelativeLayout.java:268)
12-22 16:08:42.120: E/AndroidRuntime(625):  at android.view.View.requestLayout(View.java:12675)
12-22 16:08:42.120: E/AndroidRuntime(625):  at android.widget.TextView.checkForRelayout(TextView.java:6773)
12-22 16:08:42.120: E/AndroidRuntime(625):  at android.widget.TextView.setText(TextView.java:3306)
12-22 16:08:42.120: E/AndroidRuntime(625):  at android.widget.TextView.setText(TextView.java:3162)
12-22 16:08:42.120: E/AndroidRuntime(625):  at android.widget.TextView.setText(TextView.java:3137)
12-22 16:08:42.120: E/AndroidRuntime(625):  at com.socialsober.LogFragment$ListViewLoaderTask.doInBackground(LogFragment.java:267)
12-22 16:08:42.120: E/AndroidRuntime(625):  at com.socialsober.LogFragment$ListViewLoaderTask.doInBackground(LogFragment.java:1)
12-22 16:08:42.120: E/AndroidRuntime(625):  at android.os.AsyncTask$2.call(AsyncTask.java:264)
12-22 16:08:42.120: E/AndroidRuntime(625):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
12-22 16:08:42.120: E/AndroidRuntime(625):  ... 5 more
12-22 16:08:43.341: W/ActivityManager(77):   Force finishing activity com.socialsober/.MainActivity
12-22 16:08:43.341: W/WindowManager(77): Failure taking screenshot for (180x300) to layer 21010
12-22 16:08:43.861: W/ActivityManager(77): Activity pause timeout for ActivityRecord{416f0a08 com.socialsober/.MainActivity}

Answer 1

尝试检查这个Lazy load of images in ListView

这是最好的示例/教程 http://android-developers.blogspot.com.br/2010/07/multithreading-for-performance.html

希望对你有帮助。