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我做了一個簡單的代碼來從MySQL數據庫檢索一些數據，並把它們放到android listview中一切正常，但舊的項目停留在列表視圖，它添加了新的項目（數據被複制），下面是php代碼：如何在不復制數據的情況下自動刷新（添加/更新）listview項目？
$sql = "SELECT * FROM persons";
$res = mysqli_query($con,$sql);
$result = array();
while($row = mysqli_fetch_array($res)){
array_push($result,
array('id'=>$row[0],
'name'=>$row[1],
'address'=>$row[2]
));
}
echo json_encode(array("result"=>$result));
mysqli_close($con);
這裏了android代碼：
public class FetchData extends Activity{
String myJSON;
private static final String TAG_RESULTS="result";
private static final String TAG_ID = "id";
private static final String TAG_NAME = "name";
private static final String TAG_ADD ="address";
JSONArray peoples = null;
ArrayList<HashMap<String, String>> personList;
ListView list;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.test);
list = (ListView) findViewById(R.id.listView);
personList = new ArrayList<HashMap<String,String>>();
getData();
final Handler handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
refreshData();
handler.postDelayed(this, 2 * 100);
}
}, 2 * 100);
}
public void refreshData(){
}
public void getData(){
class GetDataJSON extends AsyncTask<String, Void, String>{
@Override
protected String doInBackground(String... params) {
DefaultHttpClient httpclient = new DefaultHttpClient(new BasicHttpParams());
HttpPost httppost = new HttpPost("http://192.168.1.4/get-data.php");
// Depends on your web service
httppost.setHeader("Content-type", "application/json");
InputStream inputStream = null;
String result = null;
try {
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
inputStream = entity.getContent();
// json is UTF-8 by default
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null)
{
sb.append(line + "\n");
}
result = sb.toString();
} catch (Exception e) {
// Oops
}
finally {
try{if(inputStream != null)inputStream.close();}catch(Exception squish){}
}
return result;
}
@Override
protected void onPostExecute(String result){
myJSON=result;
showdata();
}
}
GetDataJSON g = new GetDataJSON();
g.execute();
}
protected void showdata(){
try {
JSONObject jsonObj = new JSONObject(myJSON);
peoples = jsonObj.getJSONArray(TAG_RESULTS);
for(int i=0;i<peoples.length();i++){
JSONObject c = peoples.getJSONObject(i);
String id = c.getString(TAG_ID);
String name = c.getString(TAG_NAME);
String address = c.getString(TAG_ADD);
HashMap<String,String> persons = new HashMap<String,String>();
persons.put(TAG_ID,id);
persons.put(TAG_NAME,name);
persons.put(TAG_ADD,address);
personList.add(persons);
}
ListAdapter adapter = new SimpleAdapter(
FetchData.this, personList, R.layout.list_item,
new String[]{TAG_ID,TAG_NAME,TAG_ADD},
new int[]{R.id.id, R.id.name, R.id.address}
);
list.setAdapter(adapter);
} catch (JSONException e) {
e.printStackTrace();
}
}
}
我想如果MySQL數據庫中的數據改變爲具體的項目自動更新特定列表視圖項，並添加新項目，而無需複製