我已经搜索过,但无法为我的问题找到合适的解决方案。我正在从服务器接收数据并显示它,我希望将此数据存储在本地,最好是存储在SharedPreferences
文件中。如果可以访问Internet,则应该存储和更新数据。如果没有Internet访问,则应显示此数据。
下面是我的代码
package com.timetable;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Set;
import org.apache.http.NameValuePair;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.ListActivity;
import android.content.Context;
import android.content.Intent;
import android.net.ParseException;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import android.widget.Toast;
public class MondayTimeTable_TE_Elex extends ListActivity {
// JSON Node names
private static String TAG_ID = "id";
private static String TAG_NAME = "name";
String FILENAME = "monday_te_elex_file";
FileInputStream fis;
ListView listViewItem;
// contacts JSONArray
JSONArray monday_te_elex = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_monday_time_table_te_elex);
new PlaceOrder().execute();
listViewItem = getListView();
}
ArrayList<HashMap<String, String>> categoriesList;
class PlaceOrder extends AsyncTask<Void, Void, Void> {
@Override
protected Void doInBackground(Void... params) {
// TODO Auto-generated method stub
InputStream inputStream = null;
String result = null;
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
// Example for param :
// nameValuePairs.add(new BasicNameValuePair("id", 1));
inputStream = Request.setHttpRequest(
"http://asimmerchant.hostoi.com/TE/Elex/Monday/monday_te_elex.php",
nameValuePairs);
// Hashmap for ListView
categoriesList = new ArrayList<HashMap<String, String>>();
if (inputStream != null) {
result = StringResponse.convertResponseToString(inputStream);
result = result.trim();
}
if (result == null || result.equals("null")) {
System.out.println("Invalid request");
} else {
try {
JSONArray jArray = new JSONArray(result);
JSONObject json_data = null;
for (int i = 0; i < jArray.length(); i++) {
json_data = jArray.getJSONObject(i);
try {
String id = json_data.getString(TAG_ID);
String name = json_data.getString(TAG_NAME);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_ID, id);
map.put(TAG_NAME, name);
categoriesList.add(map);
} catch (ParseException e) {
e.printStackTrace();
}
}
} catch (JSONException e1) {
Toast.makeText(getBaseContext(), "ERROR", Toast.LENGTH_LONG)
.show();
} catch (ParseException e1) {
Toast.makeText(getBaseContext(), "Error", Toast.LENGTH_LONG)
.show();
}
}
return null;
}
@Override
protected void onPostExecute(Void result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(MondayTimeTable_TE_Elex.this,
categoriesList, R.layout.list, new String[] { TAG_NAME},
new int[] { R.id.name });
setListAdapter(adapter);
/**
* Selecting single ListView item
*/
}
}
}
SharedPreferences
不能仅存储原始类型,因此您不能使用它来存储Collection
。您可以使用序列化将其写入内部存储中,但可能会有些棘手。我建议您将JSONObject
/ JSONArray
(结果取决于您的情况)存储在SharedPreferences
as中String
。
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我来说两句