Android ListViewWithJSONFromURL 在我的应用程序中，我使用JSON URL解析数据。我想在ListVIEW中显示数据和图像。但是我只得到数据，我没有得到它显示的空白图像。但是如果我给R.Dabable。Image 1显示图像，但我想在空白图像中，我只想调整我的图像。在URL中，它也正确显示我测试了。代码值也传递正确，可以请任何人帮我

ImageAdapterNew.java：

public class ImageAdapterNew extends Activity {

    ListView mListView;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);    

        // URL to the JSON data         
        String strUrl = "http://indianpoliticalleadersmap.com/android/DemoSchool/json/json_item.php";

        // Creating a new non-ui thread task to download json data 
        DownloadTask downloadTask = new DownloadTask();

        // Starting the download process
        downloadTask.execute(strUrl);

        // Getting a reference to ListView of activity_main
        mListView = (ListView) findViewById(R.id.lv_countries);


    }

    /** A method to download json data from url */
    private String downloadUrl(String strUrl) throws IOException{
        String data = "";
        InputStream iStream = null;
        try{
                URL url = new URL(strUrl);

                // 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();

                BufferedReader br = new BufferedReader(new InputStreamReader(iStream));

                StringBuffer sb  = new StringBuffer();

                String line = "";
                while( ( line = br.readLine())  != null){
                    sb.append(line);
                }

                data = sb.toString();

                br.close();

        }catch(Exception e){
                Log.d("Exception while downloading url", e.toString());
        }finally{
                iStream.close();
        }

        return data;
    }



    /** AsyncTask to download json data */
    private class DownloadTask extends AsyncTask<String, Integer, String>{
        String data = null;
                @Override
                protected String doInBackground(String... url) {
                        try{
                            data = downloadUrl(url[0]);

                        }catch(Exception e){
                            Log.d("Background Task",e.toString());
                        }
                        return data;
                }

                @Override
                protected void onPostExecute(String result) {

                        // The parsing of the xml data is done in a non-ui thread 
                        ListViewLoaderTask listViewLoaderTask = new ListViewLoaderTask();

                        // Start parsing xml data
                        listViewLoaderTask.execute(result);                        

                }
    }

    /** AsyncTask to parse json data and load ListView */
    private class ListViewLoaderTask extends AsyncTask<String, Void, SimpleAdapter>{

        JSONObject jObject;
        // Doing the parsing of xml data in a non-ui thread 
        @Override
        protected SimpleAdapter doInBackground(String... strJson) {
            try{
                jObject = new JSONObject(strJson[0]);
                Schedule1 countryJsonParser = new Schedule1();
                countryJsonParser.parse(jObject);
            }catch(Exception e){
                Log.d("JSON Exception1",e.toString());
            }

            // Instantiating json parser class
            Schedule1 countryJsonParser = new Schedule1();

            // A list object to store the parsed countries list
            List<HashMap<String, Object>> schedule = null;

            try{
                // Getting the parsed data as a List construct
                schedule = countryJsonParser.parse(jObject);
            }catch(Exception e){
                Log.d("Exception",e.toString());
            }          

            // Keys used in Hashmap 
            String[] from = { "itemname","image"};

            // Ids of views in listview_layout
            int[] to = { R.id.tv_country,R.id.iv_flag};

            // Instantiating an adapter to store each items
            // R.layout.listview_layout defines the layout of each item         
            SimpleAdapter adapter = new SimpleAdapter(getBaseContext(), schedule, R.layout.lv_layout, from, to);  

            return adapter;
        }

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

            // Setting adapter for the listview
            mListView.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("flag_path");
                ImageLoaderTask imageLoaderTask = new ImageLoaderTask();

                HashMap<String, Object> hmDownload = new HashMap<String, Object>();
                hm.put("flag_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("flag_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 = getBaseContext().getCacheDir();

                // Temporary file to store the downloaded image 
                File tmpFile = new File(cacheDirectory.getPath() + "/india_"+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 ) mListView.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(); 
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.print, menu);
        return true;
    }
}

公共类ImageAdapterNew扩展活动{
列表视图；
@凌驾
创建时的公共void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.activity_main）；
//指向JSON数据的URL
字符串strUrl=”http://indianpoliticalleadersmap.com/android/DemoSchool/json/json_item.php";
//创建新的非ui线程任务以下载json数据
DownloadTask DownloadTask=新的DownloadTask（）；
//开始下载过程
下载任务。执行（strUrl）；
//获取对活动“”的ListView的引用
mListView=（ListView）findViewById（R.id.lv_国家）；
}
/**从url下载json数据的方法*/
私有字符串下载URL（字符串strUrl）引发IOException{
字符串数据=”；
InputStream iStream=null；
试一试{
URL=新URL（strUrl）；
//创建http连接以与url通信
HttpURLConnection urlConnection=（HttpURLConnection）url.openConnection（）；
//连接到url
urlConnection.connect（）；
//从url读取数据
iStream=urlConnection.getInputStream（）；
BufferedReader br=新的BufferedReader（新的InputStreamReader（iStream））；
StringBuffer sb=新的StringBuffer（）；
字符串行=”；
而（（line=br.readLine（））！=null）{
某人附加（行）；
}
data=sb.toString（）；
br.close（）；
}捕获（例外e）{
Log.d（“下载url时出现异常”，例如toString（））；
}最后{
iStream.close（）；
}
返回数据；
}
/**AsyncTask下载json数据*/
私有类DownloadTask扩展了AsyncTask{
字符串数据=null；
@凌驾
受保护的字符串doInBackground（字符串…url）{
试一试{
数据=下载url（url[0]）；
}捕获（例外e）{
Log.d（“后台任务”，例如toString（））；
}
返回数据；
}
@凌驾
受保护的void onPostExecute（字符串结果）{
//xml数据的解析在非ui线程中完成
ListViewLoaderTask ListViewLoaderTask=新建ListViewLoaderTask（）；
//开始解析xml数据
listViewLoaderTask.execute（结果）；
}
}
/**AsyncTask解析json数据并加载ListView*/
私有类ListViewLoaderTask扩展异步任务{
JSONObject jObject；
//在非ui线程中解析xml数据
@凌驾
受保护的SimpleAdapter doInBackground（字符串…strJson）{
试一试{
jObject=新的JSONObject（strJson[0]）；
Schedule1 countryJsonParser=新Schedule1（）；
parse（jObject）；
}捕获（例外e）{
d（“JSON例外1”，例如toString（））；
}
//实例化json解析器类
Schedule1 countryJsonParser=新Schedule1（）；
//用于存储已解析的国家/地区列表的列表对象
列表计划=空；
试一试{
//将解析后的数据作为列表构造获取
schedule=countryJsonParser.parse（jObject）；
}捕获（例外e）{
Log.d（“异常”，例如toString（））；
}          
//Hashmap中使用的键
字符串[]from={“itemname”，“image”}；
//listview\u布局中的视图ID
int[]to={R.id.tv_country，R.id.iv_flag}；
//实例化适配器以存储每个项
//R.layout.listview\u布局定义每个项目的布局
simpledapter adapter=newsimpledapter（getBaseContext（），schedule，R.layout.lv_layout，from，to）；
返回适配器；
}
/**由Android在“doInBackground”上调用*/
@凌驾
受保护的void onPostExecute（SimpleAdapter适配器）{
//设置listview的适配器
mListView.setAdapter（适配器）；
for（int i=0；i在我自己开发一个从服务器下载图像的listview时遇到了这个问题。我的问题是因为我使用了一个免费的云服务器来托管我的数据库，我从那里获取要解析的数据

虽然图像下载和解析可能需要更长的时间，但在这种情况下，我会制作一个后台线程来提示用户数据正在从数据库下载

希望这有帮助：）

尽管如此，您仍可以尝试以下代码段来解析图像：

   public static Drawable LoadImageFromWebOperations(String http://indianpoliticalleadersmap.com//android//DemoSchool//images//image1.png) {
        try {
            InputStream is = (InputStream) new URL(url).getContent();
            Drawable d = Drawable.createFromStream(is, "src name");
            return d;
        } catch (Exception e) {
            return null;
        }
    }

嗨，你说的我没有得到什么，你能再一次解释我的答案吗？请你试试。我必须在这里添加这个代码，你能告诉我这个代码应该作为活动/片段类中的一个方法添加吗？在你的情况下，这是时间表1.java。如果它对你有帮助，请考虑对这个答案进行投票。否则我会非常乐意为您提供更多帮助。：）
   public static Drawable LoadImageFromWebOperations(String http://indianpoliticalleadersmap.com//android//DemoSchool//images//image1.png) {
        try {
            InputStream is = (InputStream) new URL(url).getContent();
            Drawable d = Drawable.createFromStream(is, "src name");
            return d;
        } catch (Exception e) {
            return null;
        }
    }