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异步任务+JSON解析+ListView分页

2016-05-23 11:36 435 查看 
异步任务+JSON解析+ListView分页
一、利用异步任务+JSON解析+ListView分页来实现网络访问数据显示在ListView中：（一）、示例代码：
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;
@Override
protectedvoid 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);
 }
     }
     @Override
publicvoid 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...");
   }
     @Override
protectedvoid onPreExecute() {
super.onPreExecute();
pDialog.show();
   }
  @Override
protectedbyte[] 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;
   }
  @Override
protectedvoid 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;
}
}
二、利用异步任务+JSON解析+ListView分页+自定义适配器 来实现网络访问数据显示在ListView中：（一）、示例代码：
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;
 @Override
protectedvoid 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() {
 @Override
publicvoid onScrollStateChanged(AbsListView view, int scrollState) {
if (isBottom) {
layout_main_more.setVisibility(View.VISIBLE);
    } else {
layout_main_more.setVisibility(View.GONE);
    }
    }
 @Override
publicvoid 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...");
   }
  @Override
protectedvoid onPreExecute() {
super.onPreExecute();
pDialog.show();
   }
  @Override
protectedbyte[] 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;
   }
  @Override
protectedvoid 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;
   }
 @Override
publicint getCount() {
returnlist.size();
   }
 @Override
public Object getItem(int position) {
returnlist.get(position);
   }
 @Override
publiclong getItemId(int position) {
return position;
   }
 @Override
public 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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