异步任务+JSON解析+ListView分页
异步任务+JSON解析+ListView分页
publicclass MainActivity extends Activity {privatestaticfinal String TAG = "MainActivity";private ListView listView_main_newslist;private LinearLayout layout_main_more;private String urlString = "http://192.168.125.140:8080/AndroidServer/ShowQuestionlist?page=";privatebooleanisBottom = false;privateintcurPage = 1;private SimpleAdapter adapter = null;private List<Map<String, String>> totalList = null;@Overrideprotectedvoid onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);listView_main_newslist = (ListView) findViewById(R.id.listView_main_newslist);layout_main_more = (LinearLayout) findViewById(R.id.layout_main_more);
// 执行异步任务,获取劲松字符串
new MyTask(this).execute(urlString);// 给listview设置适配器。数据源随着页面变化而不断追加新的数据totalList = new ArrayList<Map<String, String>>();adapter = new SimpleAdapter(this, totalList,R.layout.item_listview_main, new String[] { "question" },newint[] { R.id.text_item_listview_title });listView_main_newslist.setAdapter(adapter);// 给ListView设置滚动监听器listView_main_newslist.setOnScrollListener(new OnScrollListener() {
@Override
publicvoid onScrollStateChanged(AbsListView view, int scrollState) {if (isBottom) {layout_main_more.setVisibility(View.VISIBLE);} else {layout_main_more.setVisibility(View.GONE);}}@Overridepublicvoid onScroll(AbsListView view, int firstVisibleItem,int visibleItemCount, int totalItemCount) {isBottom = ((firstVisibleItem + visibleItemCount) == totalItemCount);}}publicvoid clickButton(View view) {switch (view.getId()) {case R.id.layout_main_more:curPage++;new MyTask(this).execute(urlString + curPage);layout_main_more.setVisibility(View.GONE);break;default:break;}}class MyTask extends AsyncTask<String, Void, byte[]> {private Context context;private ProgressDialog pDialog;public MyTask(Context context) {this.context = context;pDialog = new ProgressDialog(context);pDialog.setIcon(R.drawable.ic_launcher);pDialog.setTitle("提示:");pDialog.setMessage("数据加载中...");}@Overrideprotectedvoid onPreExecute() {super.onPreExecute();pDialog.show();}@Overrideprotectedbyte[] doInBackground(String... params) {BufferedInputStream bis = null;ByteArrayOutputStream baos = new ByteArrayOutputStream();try {URL url = new URL(params[0]);HttpURLConnection httpConn = (HttpURLConnection) url .openConnection();if (httpConn.getResponseCode() == 200) {bis = new BufferedInputStream(httpConn.getInputStream());byte[] buffer = newbyte[8 * 1024];int c = 0;while ((c = bis.read(buffer)) != -1) {baos.write(buffer, 0, c);baos.flush();}return baos.toByteArray();}} catch (Exception e) {e.printStackTrace();} finally {try {if (bis != null) {bis.close();}baos.close();} catch (IOException e) {e.printStackTrace();}}returnnull;}@Overrideprotectedvoid onPostExecute(byte[] result) {super.onPostExecute(result);if (result != null) {// 开始执行json解析try {String data = new String(result, "utf-8");// 将异步任务访问到的字节数组转成字符串,再通过json解析成list集合List<Map<String, String>> list = jsonToList(data);totalList.addAll(list);adapter.notifyDataSetChanged();} catch (Exception e) {e.printStackTrace();}} else {Toast.makeText(context, "网络异常,加载失败!", Toast.LENGTH_SHORT) .show();}pDialog.dismiss();}}// 解析json字符串,生成list集合private List<Map<String, String>> jsonToList(String jsonString) {List<Map<String, String>> list = new ArrayList<Map<String, String>>();try {JSONObject jsonObject = new JSONObject(jsonString);JSONArray jsonArray = jsonObject.getJSONArray("result");for (int i = 0; i < jsonArray.length(); i++) {Map<String, String> map = new HashMap<String, String>();JSONObject jsonObject2 = jsonArray.getJSONObject(i);String data = jsonObject2.getString("question");map.put("question", data);list.add(map);}return list;} catch (JSONException e) {e.printStackTrace();}returnnull;}}
publicclass MainActivity extends Activity {privatestaticfinal String TAG = "MainActivity";private ListView listView_main_newslist;private LinearLayout layout_main_more;private String urlString = "http://192.168.56.1:8080/AndroidServer/ShowQuestionlist?page=";privatebooleanisBottom = false;privateintcurPage = 1;private MyAdapter adapter = null;private List<Map<String, String>> totalList = null;@Overrideprotectedvoid onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);listView_main_newslist = (ListView) findViewById(R.id.listView_main_newslist);layout_main_more = (LinearLayout) findViewById(R.id.layout_main_more);// 执行异步任务,获取劲松字符串new MyTask(this).execute(urlString);// 给listview设置适配器。数据源随着页面变化而不断追加新的数据totalList = new ArrayList<Map<String, String>>();// adapter = new SimpleAdapter(this, totalList,// R.layout.item_listview_main, new String[] { "question" },// new int[] { R.id.text_item_listview_title });// 自定义适配器。adapter = MyAdapter(this, totalList);listView_main_newslist.setAdapter(adapter);// 给ListView设置滚动监听器listView_main_newslist.setOnScrollListener(new OnScrollListener() {@Overridepublicvoid onScrollStateChanged(AbsListView view, int scrollState) {if (isBottom) {layout_main_more.setVisibility(View.VISIBLE);} else {layout_main_more.setVisibility(View.GONE);}}@Overridepublicvoid onScroll(AbsListView view, int firstVisibleItem,int visibleItemCount, int totalItemCount) {isBottom = ((firstVisibleItem + visibleItemCount) == totalItemCount);}});}publicvoid clickButton(View view) {switch (view.getId()) {case R.id.layout_main_more:curPage++;new MyTask(this).execute(urlString + curPage);layout_main_more.setVisibility(View.GONE);break;default:break;}}class MyTask extends AsyncTask<String, Void, byte[]> {private Context context;private ProgressDialog pDialog;public MyTask(Context context) {this.context = context;pDialog = new ProgressDialog(context);pDialog.setIcon(R.drawable.ic_launcher);pDialog.setTitle("提示:");pDialog.setMessage("数据加载中...");}@Overrideprotectedvoid onPreExecute() {super.onPreExecute();pDialog.show();}@Overrideprotectedbyte[] doInBackground(String... params) {BufferedInputStream bis = null;ByteArrayOutputStream baos = new ByteArrayOutputStream();try {URL url = new URL(params[0]);HttpURLConnection httpConn = (HttpURLConnection) url.openConnection();if (httpConn.getResponseCode() == 200) {bis = new BufferedInputStream(httpConn.getInputStream());byte[] buffer = newbyte[8 * 1024];int c = 0;while ((c = bis.read(buffer)) != -1) {baos.write(buffer, 0, c);baos.flush();}return baos.toByteArray();}} catch (Exception e) {e.printStackTrace();} finally {try {if (bis != null) {bis.close();}baos.close();} catch (IOException e) {e.printStackTrace();}}returnnull;}@Overrideprotectedvoid onPostExecute(byte[] result) {super.onPostExecute(result);if (result != null) {// 开始执行json解析try {String data = new String(result, "utf-8");// 将异步任务访问到的字节数组转成字符串,再通过json解析成list集合List<Map<String, String>> list = jsonToList(data);totalList.addAll(list);adapter.notifyDataSetChanged();} catch (Exception e) {e.printStackTrace();}} else {Toast.makeText(context, "网络异常,加载失败!", Toast.LENGTH_SHORT).show();}pDialog.dismiss();}}// 解析json字符串,生成list集合private List<Map<String, String>> jsonToList(String jsonString) {List<Map<String, String>> list = new ArrayList<Map<String, String>>();try {JSONObject jsonObject = new JSONObject(jsonString);JSONArray jsonArray = jsonObject.getJSONArray("result");for (int i = 0; i < jsonArray.length(); i++) {Map<String, String> map = new HashMap<String, String>();JSONObject jsonObject2 = jsonArray.getJSONObject(i);String data = jsonObject2.getString("question");map.put("question", data);list.add(map);}return list;} catch (JSONException e) {e.printStackTrace();}returnnull;}class MyAdapter extends BaseAdapter {private Context context;private List<Map<String, String>> list = null;public MyAdapter(Context context, List<Map<String, String>> list) {this.context = context;this.list = list;}@Overridepublicint getCount() {returnlist.size();}@Overridepublic Object getItem(int position) {returnlist.get(position);}@Overridepubliclong getItemId(int position) {return position;}@Overridepublic View getView(int position, View convertView, ViewGroup parent) {ViewHolder mHolder = null;if (convertView == null) {mHolder = new ViewHolder();convertView = LayoutInflater.from(context).inflate(
R.layout.item_listview_main, parent, false);
mHolder.text_item_listview_title = (TextView) convertView.findViewById(R.id.text_item_listview_title);convertView.setTag(mHolder);} else {mHolder = (ViewHolder) convertView.getTag();}mHolder.text_item_listview_title.setText(list.get(position).get("question").toString());return convertView;}class ViewHolder {private TextView text_item_listview_title;}}}
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