我正在做一个应用程序可以每 1 分钟更新一次数据，数据将从服务器上的数据库 mysql 显示在我的应用程序 android 的列表视图上。我的问题是第一个显示数据没问题，但是当在listview上显示第二个数据时，第一个和第二个的数据是重复的。你能帮帮我吗！源代码：
public class Hoadon extends Activity {
JSONArray jArray;
String result = null;
InputStream is = null;
StringBuilder sb = null;
ArrayList<String> al = new ArrayList<String>();
ArrayList<String> al1 = new ArrayList<String>();
ArrayList<String> al2 = new ArrayList<String>();
ArrayList<String> al3 = new ArrayList<String>();
ArrayList<String> al1a = new ArrayList<String>();
String date;
String name;
String address;
String url;
String code;
int responseCode;
private String IDinvoice;
private TimerTask mTimerTask;
private Timer t=new Timer();
private final Handler handler=new Handler();
private ListView listview;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.hoadon);
int currentOrientation = getResources().getConfiguration().orientation;
if (currentOrientation == Configuration.ORIENTATION_LANDSCAPE) {
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_SENSOR_PORTRAIT);
}
else {
setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_SENSOR_PORTRAIT);
}
try {
URL url = new URL("http://longvansolution.tk/monthlytarget.php");
URLConnection connection = url.openConnection();
connection.setConnectTimeout(2000);
HttpURLConnection httpConnection = (HttpURLConnection) connection;
responseCode = httpConnection.getResponseCode();
} catch (Exception e) {
}
try {
if (isNetworkAvailable() == true
//&& responseCode == HttpURLConnection.HTTP_OK
) {
//new LoadData().execute();
al.clear();
al1.clear();
al2.clear();
al3.clear();
al1a.clear();
doTimerTask();
} else {
AlertDialog.Builder ad = new AlertDialog.Builder(this);
ad.setMessage("No Internet Connection available!!!");
ad.show();
}
} catch (Exception e) {
}
Bundle extras = getIntent().getExtras();
if (extras != null) {
IDinvoice = extras.getString("IDinvoice");
}
}
public void doTimerTask(){
mTimerTask = new TimerTask() {
public void run() {
handler.post(new Runnable() {
public void run() {
new LoadData().execute();
Log.d("TIMER", "TimerTask run");
}
});
}};
// public void schedule (TimerTask task, long delay, long period)
t.schedule(mTimerTask, 500, 10000); //
}
@Override
public void onBackPressed() {
//do something with bitmap
}
private class LoadData extends AsyncTask<Void, Void, Void> {
private ProgressDialog progressDialog;
@Override
// can use UI thread here
protected void onPreExecute() {
this.progressDialog = ProgressDialog.show(
Hoadon.this, "", " Loading...");
}
@Override
protected void onPostExecute(final Void unused) {
this.progressDialog.dismiss();
try {
listview = (ListView) findViewById(R.id.listView1);
this.progressDialog.dismiss();
listview.setAdapter(new DataAdapter(Hoadon.this,
al.toArray(new String[al.size()]), al1a
.toArray(new String[al1a.size()]), al1
.toArray(new String[al1.size()]), al2
.toArray(new String[al2.size()])));
listview.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// TODO Auto-generated method stub
String t = al3.get(position);
Intent i = new Intent(Hoadon.this,
Signature.class);
i.putExtra("url", t);
startActivity(i);
}
});
} catch (Exception e) {
Toast.makeText(getApplicationContext(), e.toString(),
Toast.LENGTH_LONG).show();
}
}
@Override
protected Void doInBackground(Void... params) {
// TODO Auto-generated method stub
// HTTP post
try {
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
HttpClient httpclient = new DefaultHttpClient();
try {
HttpPost httppost = new HttpPost(
"http://longvansolution.tk/monthlytarget.php");
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
} catch (Exception e) {
Toast.makeText(getApplicationContext(), e.toString(),
Toast.LENGTH_LONG).show();
}
// buffered reader
try {
BufferedReader reader = new BufferedReader(
new InputStreamReader(is, "iso-8859-1"), 80);
sb = new StringBuilder();
sb.append(reader.readLine() + "\n");
String line = "0";
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
result = sb.toString();
} catch (Exception e) {
Toast.makeText(getApplicationContext(), e.toString(),
Toast.LENGTH_LONG).show();
}
try {
jArray = new JSONArray(result);
JSONObject json_data = null;
for (int i = 0; i < jArray.length(); i++) {
json_data = jArray.getJSONObject(i);
date = json_data.getString("date");
address = json_data.getString("address");
name = json_data.getString("name");
url = json_data.getString("url");
code = json_data.getString("code");
al.add(date);
al1a.add(code);
al1.add(name);
al2.add(address);
al3.add(url);
}
} catch (JSONException e) {
Toast.makeText(getApplicationContext(), e.toString(),
Toast.LENGTH_LONG).show();
}
} catch (ParseException e) {
// Log.e("log_tag", "Error in http connection" + e.toString());
Toast.makeText(getApplicationContext(), e.toString(),
Toast.LENGTH_LONG).show();
} catch (Exception e) {
// Log.e("log_tag", "Error in http connection" + e.toString());
Toast.makeText(getApplicationContext(), e.toString(),
Toast.LENGTH_LONG).show();
}
return null;
}
}
public boolean isNetworkAvailable() {
ConnectivityManager cm = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo networkInfo = cm.getActiveNetworkInfo();
// if no network is available networkInfo will be null, otherwise check
// if we are connected
if (networkInfo != null && networkInfo.isConnected()) {
// Log.i("net status:", "Online...!!!");
return true;
}
// Log.i("net status:", "offline...!!!");
return false;
}
}
源数据适配器
public class DataAdapter extends BaseAdapter {
Context mContext;
private LayoutInflater mInflater;
String[] date;
String[] code;
String[] address;
String[] name;
public DataAdapter(Context c, String[] date,String[] code, String[] name, String[] address) {
this.date = date;
this.code=code;
this.name = name;
this.address = address;
mContext = c;
mInflater = LayoutInflater.from(c);
}
public void clearData() {
// clear the data
Arrays.fill(date, null);
Arrays.fill(code, null);
Arrays.fill(address, null);
Arrays.fill(name, null);
}
public int getCount() {
return date.length;
}
public Object getItem(int position) {
return position;
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
if (convertView == null) {
convertView = mInflater.inflate(R.layout.customgrid, parent, false);
holder = new ViewHolder();
holder.date = (TextView) convertView.findViewById(R.id.date);
holder.code=(TextView)convertView.findViewById(R.id.mahd);
holder.name = (TextView) convertView.findViewById(R.id.name);
holder.address = (TextView) convertView.findViewById(R.id.address);
if (position == 0) {
convertView.setTag(holder);
}
} else {
holder = (ViewHolder) convertView.getTag();
}
try {
holder.date.setText(date[position]);
holder.code.setText(code[position]);
holder.name.setText(name[position]);
holder.address.setText(address[position]);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return convertView;
}
static class ViewHolder {
TextView date,code;
TextView name, address;
}
}