Android SimpleAdapter动态显示Bitmap图片

因为要实现从服务器中读取商品图片显示在listview中，之前写的Demo是不考虑显示图片，而是采用了本地图片进行演示，因为只需要读取文本信息，所以采用了比较简单的SimpleAdapter来实现相关功能。

具体实现如下：

 

 

 

 

Java

 

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class GetProductUserAll extends AsyncTask<String, String, String> {           @Override         protected void onPreExecute() {             super.onPreExecute();             pDialog = new ProgressDialog(GetProductActivity.this);             pDialog.setMessage("loading..");             pDialog.setIndeterminate(false);             pDialog.setCancelable(true);             pDialog.show();         }           protected String doInBackground(String... args) {               String userIDString = String.valueOf(userID);               // Building Parameters             List<NameValuePair> params = new ArrayList<NameValuePair>();             params.add(new BasicNameValuePair("userID", userIDString));               // url to get all products list             MyApplication myApplication = (MyApplication) getApplication();             String url_user_getProduct = myApplication.getIP()                     + "vendingmachine/getProduct_user.php";               JSONObject json = jsonParser.makeHttpRequest(url_user_getProduct,                     "GET", params);               try {                 success = json.getInt(TAG_SUCCESS);                 if (success == 1) {                     getProductArray = json.getJSONArray("getProducts");                     getProdcutList.clear();                     for (int i = 0; i < getProductArray.length(); i++) {                         JSONObject c = getProductArray.getJSONObject(i);                           // Storing each json item in variable                         String Number = c.getString("GetGoodNumber");                         String numberOne = Number.substring(0, 4);                         String numberTwo = Number.substring(4, 8);                         String numberThree = Number.substring(8, 12);                         String getProductNumber = numberOne + ' ' + numberTwo                                 + ' ' + numberThree;                           // creating new HashMap                         HashMap<String, Object> map = new HashMap<String, Object>();                         // adding each child node to HashMap key => value                         map.put("OrderID", c.getString("OrderID"));                         map.put("GoodName", c.getString("GoodName"));                         map.put("GetGoodNumber", getProductNumber);                         map.put("Price", c.getString("Price"));                           // adding HashList to ArrayList                         getProdcutList.add(map);                     }                 } else {                     // failed to create product                   }             } catch (JSONException e) {                 e.printStackTrace();             }               return null;         }           protected void onPostExecute(String file_url) {             // dismiss the dialog once done             pDialog.dismiss();               if (success == 1) {                 // updating listview                 // HashMap<String, String>中的key                 String[] from = { "OrderID", "GoodName", "GetGoodNumber",                         "Price"};                 // list_item.xml中对应的控件ID                 int[] to = { R.id.getProduct_orderID,                         R.id.getProduct_good_name, R.id.getProduct_good_number,                         R.id.getProduct_good_price};                 SimpleAdapter adapter = new SimpleAdapter(mContext,                         getProdcutList, R.layout.getproduct_list, from, to);                                  listView.setAdapter(adapter);                 // mPullRefreshListView.onRefreshComplete();             } else {               }         }     }

只截取了从服务器中读取数据并显示在listview中的代码

当我想显示图片的时候，仅仅添加map.put(“Image”, c.getString(“Image”)); 是无法得到图片信息的

 

步骤：

服务器中图片的存储存的是路径名，php返回的JSON值也仅仅是路径名而已，所以，如果Android需要通过给定的路径读取到图片并转换成Bitmap

1. 首先，我们需要设置缓冲区大小

 

1	private static final int IO_BUFFER_SIZE = 4 * 1024;

2. 接着实现ImageLoad类

 

 

 

 

Java

 

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public class ImageLoad {     /***** Get Image Resource from URL (Start) *****/     private static final int IO_BUFFER_SIZE = 4 * 1024;     private static final String Tag = "ImageLoad";       public static Bitmap loadBitmap(String url) {         Bitmap bitmap = null;         InputStream in = null;         BufferedOutputStream out = null;           try {             in = new BufferedInputStream(new URL(url).openStream(),                     IO_BUFFER_SIZE);               final ByteArrayOutputStream dataStream = new ByteArrayOutputStream();             out = new BufferedOutputStream(dataStream, IO_BUFFER_SIZE);             copy(in, out);             out.flush();               final byte[] data = dataStream.toByteArray();             BitmapFactory.Options options = new BitmapFactory.Options();             // options.inSampleSize = 1;               bitmap = BitmapFactory.decodeByteArray(data, 0, data.length,                     options);             Log.i(Tag, "load Bitmap success from: " + url);         } catch (IOException e) {             Log.e(Tag, "Could not load Bitmap from: " + url);         } finally {             closeStream(in);             closeStream(out);         }         return bitmap;     }       private static void closeStream(Closeable stream) {         if (stream != null) {             try {                 stream.close();             } catch (IOException e) {                 android.util.Log.e(Tag, "Could not close stream", e);             }         }     }       private static void copy(InputStream in, OutputStream out)             throws IOException {         byte[] b = new byte[IO_BUFFER_SIZE];         int read;         while ((read = in.read(b)) != -1) {             out.write(b, 0, read);         }     }   }

3. 再在之前的源程序中加入获取服务器中图片的代码：

 

 

 

 

Java

 

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ImageLoad imageLoad = new ImageLoad();   String imageURLString = myApplication.getIP() + "vendingmachine/" + c.getString("ImageID"); map.put("ImageID",(Bitmap) imageLoad.loadBitmap(imageURLString));

4.修改SimpleAdapter from和to, 把图片信息加进去，注意要一一对齐

 

 

 

 

Java

 

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String[] from = { "OrderID", "GoodName", "GetGoodNumber","Price", "ImageID" }; // list_item.xml中对应的控件ID int[] to = { R.id.getProduct_orderID,R.id.getProduct_good_name, R.id.getProduct_good_number,         R.id.getProduct_good_price, R.id.getProduct_good_image };   SimpleAdapter adapter = new SimpleAdapter(mContext,         getProdcutList, R.layout.getproduct_list, from, to);

这时候运行，发现之前自定义的本地图片已经不显示了，但是获取的图片为空白，而在ImageLoad中返回的Log.i日志可以看到，URL也是正确的，这意味着Android客户端已经得到了图片，那为什么没有显示在listview中呢？

这时候翻整个工程的日志你可以看到这样一行：

 

1	I/System.out(284): resolveUri failed on bad bitmap uri: android.graphics.drawable.BitmapDrawable@485d7dd0

这是因为如果ListView要显示外部资源的话必须要设置ViewBinder，通过ViewBinder的绑定机制来显示网络资源

 

 

 

 

Java

 

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//实现ViewBinder接口     class MyViewBinder implements ViewBinder     {         /**          * view：要板顶数据的视图          * data：要绑定到视图的数据          * textRepresentation：一个表示所支持数据的安全的字符串，结果是data.toString()或空字符串，但不能是Null          * 返回值：如果数据绑定到视图返回真，否则返回假          */         @Override         public boolean setViewValue(View view, Object data,                 String textRepresentation) {             if((view instanceof ImageView)&(data instanceof Bitmap))             {                 ImageView iv = (ImageView)view;                 Bitmap bmp = (Bitmap)data;                 iv.setImageBitmap(bmp);                 return true;             }             return false;         }     }

 

并在onPostExecute函数中加入

 

1	adapter.setViewBinder(new MyViewBinder());

这样即可实现通过SimpleAdapter获取服务器中，网络或者是文件中的图片，显示在listview中