ListView加载网络数据和图片.doc

ListView加载网络数据和图片 如，从服务器端获得商品名称、价格、简介和图片，加载到Android ListView中。又如加载微博内容。需了解熟悉：1、ListView行布局，排版，getView方法这个案例可以说是实现ListView图文混排的网络版。关于在ListView中实现排版的方法，参 考：2、异步任务的实现，Handler+Thread , AsyncTask3、JSON解析方式实现思路：1、异步加载服务器访问商品数据（json格式） 封装网络访问的方法2、json数据转为Adapter数据（ListMap） 封装数据转换的方法3、Adapter先加载文本内容信息 使用AsyncTask加载网络访问的集合数据 加载ListView中的文本信息4、json数据中有图片信息（路径），异步读取加载图片 采用接口回调的方法，加载图片信息（Handler+Thread）public class HttpUtil public static final String BASE_URL = :8080/jsontest/servlet/ProductServlet;public static final String IMG_URL = :8080/jsontest/upload/;public static HttpClient httpClient = new DefaultHttpClient();/ post方法访问服务器，返回json字符串public static String getRequest(String url)String result = null;HttpGet httpGet = new HttpGet(url); try HttpResponse httpResponse = httpClient.execute(httpGet);if (httpResponse.getStatusLine().getStatusCode() = 200) result = EntityUtils.toString(httpResponse.getEntity(),utf-8); catch (Exception e) / TODO Auto-generated catch blocke.printStackTrace(); return result; / 字符串转成集合数据public static void resultString2List(ListMap list, String str,String title) try JSONObject jsonObject = new JSONObject(str);JSONArray jsonArray = jsonObject.getJSONArray(title);for (int i = 0; i jsonArray.length(); i+) JSONObject jsonObject2 = jsonArray.getJSONObject(i);Map map = new HashMap();Iterator iterator = jsonObject2.keys();while (iterator.hasNext() String key = iterator.next();Object value = jsonObject2.get(key);map.put(key, value);list.add(map); catch (JSONException e) / TODO Auto-generated catch blocke.printStackTrace(); / post方法访问服务器，返回集合数据public static ListMap getRequest2List(String url,String title)ListMap list = new ArrayListMap();resultString2List(list, url, title);return list;/ get方法访问服务器，返回json字符串public static String postRequest(String url, Map rawParams) throws ExceptionHttpPost post = new HttpPost(url);List params = new ArrayList();for (String key:rawParams.keySet() params.add(new BasicNameValuePair(key, rawParams.get(key);post.setEntity(new UrlEncodedFormEntity(params, UTF-8);HttpResponse httpResponse = httpClient.execute(post);if(httpResponse.getStatusLine().getStatusCode() = 200)String result = EntityUtils.toString(httpResponse.getEntity(); return result;return null; /post访问的方法，还可继续封装，略。异步任务，得到网络json转换的集合数据，并在完成后加载到listview中（onPostExcute方法中执行）public class MyTask extends AsyncTaskString, Void, ListMapOverrideprotected void onPreExecute() / TODO Auto-generated method stubsuper.onPreExecute();progressDialog.show();Overrideprotected void onPostExecute(ListMap result) / TODO Auto-generated method stubsuper.onPostExecute(result);adapter.setData(result);listview.setAdapter(adapter);adapter.notifyDataSetChanged();progressDialog.dismiss();Overrideprotected ListMap doInBackground(String. params) / TODO Auto-generated method stubListMap list ;String str = HttpUtil.getRequest(params0);list = HttpUtil.getRequest2List(str, products);return list;OnCreate()方法中启动异步任务：progressDialog = new ProgressDialog(this);progressDialog.setTitle(正在下载.);adapter = new MyAdapter(this);new MyTask().execute(HttpUtil.BASE_URL);Adapter:public class MyAdapter extends BaseAdapterprivate Context context;private LayoutInflater layoutInflater;private ListMap list;public MyAdapter(Context context) this.context = context;layoutInflater = layoutInflater.from(context);public List getData()return list;public void setData(ListMap data)this.list = data;Overridepublic int getCount() / TODO Auto-generated method stubreturn list.size();Overridepublic Object getItem(int position) / TODO Auto-generated method stubreturn list.get(position);Overridepublic long getItemId(int position) / TODO Auto-generated method stubreturn position;Overridepublic View getView(int position, View convertView, ViewGroup parent) / TODO Auto-generated method stubView view = null;final ViewHolder viewHolder;if (convertView = null ) convertView = layoutInflater.inflate(R.layout.item, null);viewHolder = new ViewHolder();viewHolder.id = (TextView)convertView.findViewById(R.id.textView1);viewH = (TextView)convertView.findViewById(R.id.textView2);viewHolder.address = (TextView)convertView.findViewById(R.id.textView3);viewHolder.img = (ImageView)convertView.findViewById(R.id.imageView1);convertView.setTag(viewHolder);elseviewHolder = (ViewHolder)convertView.getTag();viewHolder.id.setText(list.get(position).get(sid).toString();viewH.setText(list.get(position).get(name).toString();viewHolder.address.setText(list.get(position).get(addr).toString();/接口回调的方法，完成图片的读取;DownImage downImage = new DownImage(HttpUtil.IMG_URL+list.get(position).get(pic).toString()+.jpg);downImage.loadImage(new ImageCallBack() Overridepublic void getDrawable(Drawable drawable) / TODO Auto-generated method stubviewHolder.img.setImageDrawable(drawable););return convertView;public class ViewHolderImageView img;TextView id;TextView name;TextView address;异步加载图片的类：public class DownImage public String image_path;public DownImage(String image_path) this.image_path = image_path;public void loadImage(final ImageCallBack callBack)final Handler handler = new Handler()Overridepublic void handleMessage(Message msg) / TODO Auto-generated method stubsuper.handleMessage(msg);Drawable drawable = (Drawable) msg.obj;callBack.getDrawable(drawable);new Thread(new Runnable() Overridepublic void run() / TODO Auto-generated method stubtry Drawable drawable = Drawable.createFromStream(new URL(image_path).openStream(), );Message message = Message.obtain();message.