如何 JSON 解析来自 mysql 的图像并填充列表视图

Question

大家好，我正在尝试使用数据库中的图像填充列表视图。我已将图像上传到服务器，并采用http://www.spinner.bl.ee/images/ATE.png 之类的完整路径并将其作为varchar 存储在名为image 的数据库列中。然后我有一个.php 文件，你可以在这里看到http://spinner.bl.ee/getstocks.php，它给了我一个名为metoxes 的json 数组，其中包含所有数据。但图像有点不同（意思是路径）我该如何解决这个问题？？

在 imageview 的 android 应用程序的 java 文件中，我得到完整路径而不是图像。任何帮助将不胜感激！

我的代码

private class JsonReadTask extends AsyncTask<String, Void, String> {
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(MainActivity.this);
            pDialog.setTitle(R.string.waiting);
            pDialog.setMessage(getString(R.string.get_stocks));
            pDialog.setCancelable(false);
            pDialog.show();
        }

        @Override
        protected String doInBackground(String... params) {

            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost(params[0]);
            try {
                HttpResponse response = httpclient.execute(httppost);
                jsonResult = inputStreamToString(
                        response.getEntity().getContent()).toString();
            }

            catch (ClientProtocolException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return null;
        }

        private StringBuilder inputStreamToString(InputStream is) {
            String rLine = "";
            StringBuilder answer = new StringBuilder();
            BufferedReader rd = new BufferedReader(new InputStreamReader(is));

            try {
                while ((rLine = rd.readLine()) != null) {
                    answer.append(rLine);
                }
            }

            catch (IOException e) {
                // e.printStackTrace();
                Toast.makeText(getApplicationContext(),
                        "Error..." + e.toString(), Toast.LENGTH_LONG).show();
            }
            return answer;
        }

        @Override
        protected void onPostExecute(String result) {

            ListDrwaer();
            pDialog.dismiss();
        }

    }// end async task

    public void accessWebService() {
        JsonReadTask task = new JsonReadTask();
        // passes values for the urls string array
        task.execute(new String[] { url });
    }

    // build hash set for list view
    public void ListDrwaer() {
        List<Map<String, String>> stocksList = new ArrayList<Map<String, String>>();

        try {
            JSONObject jsonResponse = new JSONObject(jsonResult);
            JSONArray jsonMainNode = jsonResponse.optJSONArray("metoxes");
            for (int i = 0; i < jsonMainNode.length(); i++) {
                JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
                String name = jsonChildNode.optString("name");
                String price = jsonChildNode.optString("price");
                String image = jsonChildNode.getString("image");
                //Log.i("image is valid", image);
                //String outPut =  name + price;
                //BitmapFactory.decodeFile(image);
                stocksList.add(createStockList(name, price, image));
            }


        } catch (JSONException e) {
            Toast.makeText(getApplicationContext(), "Error" + e.toString(),
                    Toast.LENGTH_SHORT).show();
        }
        //byte[] image = {};
        String[] from = { "name", "price", "image" };
        //BitmapFactory.decodeByteArray(image, 50, image.length);
        int[] to = { R.id.stock_name, R.id.stock_price, R.id.dbImage };
        SimpleAdapter simpleAdapter = new SimpleAdapter(this, stocksList,
                R.layout.list_item,
                from, to);
        listView.setAdapter(simpleAdapter);
    }

    private HashMap<String, String> createStockList(String name, String price, String image) {
        HashMap<String, String> stockNameNo = new HashMap<String, String>();
        stockNameNo.put("name", name);
        stockNameNo.put("price", price);
        stockNameNo.put("image", image);
        return stockNameNo;
    }
}

提前致谢。

Answer 1

如果您的问题是您想要以http://www.spinner.bl.ee/images/ATE.png 输出的数据以http:\/\/spinner.bl.ee\/images\/ATE.png 输出，那么当org.json.JSONObject 将字符串从您的url 加载到JSONObject 时，这应该不是问题；你测试过这段代码吗？

这是一些 AsyncTask 访问您的服务器的实现；只有一个活动，MainActivity.java，然后 StockInformation.java 作为对象。

public class MainActivity extends Activity {

    ProgressDialog pDialog;
    ListView listView;
    private StockAdaptor stockAdaptor;
    String jsonResult = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_); //Just a listView, shown below
        listView = (ListView) findViewById(android.R.id.list);
        new JsonReadTask().execute("http://spinner.bl.ee/getstocks.php"); //YOUR URL JSON SERVER, IF IT IS DIFFERENT FROM THAT SUPPLIED ABOVE
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        return true; //No options
    }

    public void onStart() {
        super.onStart();

        stockAdaptor = new StockAdaptor(this); //Create a new StockAdaptor
    }

    public static String strFromStream(InputStream in) throws IOException { //Simple function, getting a String from an InputStream
        StringBuilder out = new StringBuilder();
        BufferedReader breader = new BufferedReader(new InputStreamReader(in));
        String cline;
        String newLine = System.getProperty("line.separator");
        while ((cline = breader.readLine()) != null) {
            out.append(cline);
            out.append(newLine);
        }
        return out.toString();
    }

    private class StockAdaptor extends BaseAdapter { //The stocks list adaptor

        class ViewHolder {
            TextView name;
            TextView price;
            ImageView image; 
        }

        private LayoutInflater layoutInflater;
        private StockInformation[] stocks = null; //Array of stocks
        private ListView stocksListView = null;

        public StockAdaptor(Context context) {
            super();
            layoutInflater = LayoutInflater.from(context);
        }

        public void setStockList(StockInformation[] stocksinfo) {
            this.stocks = stocksinfo;// //////////////LITERALLY THIS

        }

        @Override
        public int getCount() {
            return stocks.length;
        }

        @Override
        public Object getItem(int position) {
            return stocks[position];
        }

        public StockInformation[] getAll() { //Return the array of stocks
            return stocks;
        }

        @Override
        public long getItemId(int position) {
            return 0;
        }

        public View getView(int position, View convertView, ViewGroup parent) {
            ViewHolder holder; //New holder
            if (convertView == null) {
                convertView = layoutInflater.inflate(R.layout.list_item,
                        null);
                holder = new ViewHolder();
                // Creates the new viewholder define above, storing references to the children
                holder.name = (TextView) convertView.findViewById(R.id.name);
                holder.price = (TextView) convertView.findViewById(R.id.price);
                holder.image = (ImageView) convertView.findViewById(R.id.image);

                stocksListView = (ListView) findViewById(android.R.id.list);

                if (holder.image != null) {
                    if (holder.image.getDrawable() == null) {
                        new ImageDownloaderTask(holder.image, null)                                 .execute(stocks[position].imageurl); //Download the image using the imageurl

                    }
                }
                convertView.setTag(holder);
            } else {
                stocksListView = (ListView) findViewById(android.R.id.list);
                holder = (ViewHolder) convertView.getTag();
            }

            holder.name.setText(stocks[position].name);
            holder.price.setText(stocks[position].price);

            return convertView;
        }
    }

    private class JsonReadTask extends AsyncTask<String, Void, String> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(MainActivity.this);
            pDialog.setTitle("waiting");
            pDialog.setMessage("getting stocks");
            pDialog.setCancelable(false);
            pDialog.show();
        }

        @Override
        protected String doInBackground(String... params) {
            if (URLUtil.isValidUrl(params[0])) {
                final AndroidHttpClient client = AndroidHttpClient.newInstance("Android");
                final HttpGet getRequest = new HttpGet(params[0]);
                try {
                    HttpResponse response = client.execute(getRequest);
                    final HttpEntity httpentity = response.getEntity();
                    if (httpentity != null){
                        InputStream inputStream = null;
                        try {
                            inputStream = httpentity.getContent();
                            jsonResult = strFromStream(inputStream);
                            Log.i("", jsonResult);
                            return jsonResult;
                        } catch (IllegalArgumentException e) {
                            //
                        } finally {
                            httpentity.consumeContent();
                        }
                    }
                } catch (ClientProtocolException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                } finally {
                    client.close();
                }
            }
            return null;
        }

        @Override
        protected void onPostExecute(String result) {

            ListDrwaer();
            pDialog.dismiss();
        }

    }// end async task

    // build hash set for list view
    public void ListDrwaer() {

        try {
            if (jsonResult!=null) {
                JSONObject jsonResponse = new JSONObject(jsonResult);
                JSONArray jsonMainNode = jsonResponse.optJSONArray("metoxes");
                Vector<StockInformation> vstocks = new Vector<StockInformation>();
                for (int i = 0; i < jsonMainNode.length(); i++) {
                    JSONObject jsonChildNode = jsonMainNode.getJSONObject(i);
                    StockInformation stock = new StockInformation();
                    stock.name = jsonChildNode.optString("name");
                    stock.price = jsonChildNode.optString("price");
                    stock.imageurl = jsonChildNode.getString("image");
                    Log.i("StockLog", stock.name + stock.price + stock.imageurl);
                    vstocks.add(stock);
                }
                StockInformation[] stocks = new StockInformation[jsonMainNode.length()];

                int stockscount = jsonMainNode.length();
                for (int n = 0; n < stockscount; n++) 
                {               
                    stocks[n] = vstocks.get(n);
                }
                stockAdaptor.setStockList(stocks);
                listView.setAdapter(stockAdaptor);
            } else {
                Toast.makeText(getApplicationContext(), "Error; jsonResult null",
                        Toast.LENGTH_SHORT).show();
            }
        } catch (JSONException e) {
            Toast.makeText(getApplicationContext(), "Error" + e.toString(),
                    Toast.LENGTH_SHORT).show();
        }
    }

    private class ImageDownloaderTask extends AsyncTask<String, Void, Bitmap> {
        private final WeakReference<ImageView> imageViewReference;

        public ImageDownloaderTask(ImageView imageView, View view) {
            imageViewReference = new WeakReference<ImageView>(imageView);
        }

        @Override
        // Actual download method, run in the task thread
        protected Bitmap doInBackground(String... params) {
            // params comes from the execute() call: params[0] is the url.
            return downloadBitmap(params[0]);
        }

        @Override
        // Once the image is downloaded, associates it to the imageView
        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 {
                        //
                    }
                }

            }

        }

        Bitmap downloadBitmap(String url) {
            if(URLUtil.isValidUrl(url)){

                final AndroidHttpClient client = AndroidHttpClient.newInstance("Android");
                final HttpGet getRequest = new HttpGet(url);
                try {
                    HttpResponse response = client.execute(getRequest);
                    final int statusCode = response.getStatusLine().getStatusCode();
                    if (statusCode != HttpStatus.SC_OK) {
                        Log.w("ImageDownloader", "Error " + statusCode
                                + " while retrieving bitmap from " + url);
                        return null;
                    }

                    final HttpEntity entity = response.getEntity();
                    if (entity != null) {
                        InputStream inputStream = null;
                        try {
                            inputStream = entity.getContent();
                            try {
                                byte[] buffer = new byte[8192];
                                int bytesRead;
                                ByteArrayOutputStream output = new ByteArrayOutputStream();
                                while ((bytesRead = inputStream.read(buffer)) != -1) {
                                    output.write(buffer, 0, bytesRead);
                                }   
                                return BitmapFactory.decodeByteArray(output.toByteArray(), 0, output.toByteArray().length);
                            } catch (IllegalArgumentException e) {
                                e.printStackTrace();
                                Log.i("IAE", "in stocks");
                                return null;
                            }
                        } finally {
                            if (inputStream != null) {
                                inputStream.close();
                            }
                            entity.consumeContent();
                        }
                    }
                } catch (Exception e) {
                    getRequest.abort();
                    Log.w("ImageDownloader", "Error while retrieving bitmap from " + url);
                } finally {
                    if (client != null) {
                        client.close();
                    }
                }
                return null;

            }
            return null;
        }

    }
}

单独定义：StockInformation.java；库存对象。

public class StockInformation {
    public String name;
    public String price;
    public String imageurl; 
}

然后是xml文件：activity_.xml（只包含ListView）；

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".Activity" >

        <ListView
        android:id="@+id/android:list"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"/>
</RelativeLayout>

还有list_item.xml（就是每只股票需要的图片和两个文字）：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:minHeight="50dp"
    android:orientation="vertical" >

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >

        <ImageView
            android:id="@+id/image"
            android:layout_width="70dp"
            android:layout_height="70dp" />

        <TextView
            android:id="@+id/name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:lineSpacingExtra="3dp"
            android:paddingLeft="5dp"
            android:paddingTop="5dp"
            android:text="" />

        <TextView
            android:id="@+id/price"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:paddingLeft="5dp"
            android:paddingTop="5dp"
            android:text="" />
    </LinearLayout>

</LinearLayout>