使用 Asynctask 在列表视图中显示数据 [英] Show data in listview with Asynctask
本文介绍了使用 Asynctask 在列表视图中显示数据的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我成功地在列表视图中显示了来自 Web 服务 JSON 的数据，但我想添加 Asyntask.我可以在我的代码中放置代码 Asyntask 的位置.
I success show my data from web service JSON in listview, but I want to add Asyntask. Where I can put code Asyntask in my code.
这是我在列表视图中显示数据的代码
public class Jadwal_remix extends ListActivity {
String v_date;
JSONArray r_js = null;
ArrayList<HashMap<String, String>> myArray = new ArrayList<HashMap<String,String>>();
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.main);
String status ="";
String date = "";
String result = "";
String url = "http://10.0.2.2/remix/view_list.php";
JSONParser jParser = new JSONParser();
JSONObject json = jParser.AmbilJson(url);
try
{
r_js = json.getJSONArray("view_list");
for (int i =0; i < r_js.length(); i++)
{
String my_array = "";
JSONObject ar = r_js.getJSONObject(i);
status = ar.getString("st");
date = ar.getString("date");
result = ar.getString("result");
if (status.trim().equals("er"))
{
my_array += "Sorry "+result;
HashMap<String, String> map = new HashMap<String, String>();
map.put("result", my_array);
myArray.add(map);
}
else
{
my_array += "Date : "+date+" "+"Result : "+result;
HashMap<String, String> map = new HashMap<String, String>();
map.put("result", my_array);
myArray.add(map);
}
}
}
catch (JSONException e)
{
e.printStackTrace();
}
adapter_listview();
}
public void adapter_listview() {
ListAdapter adapter = new SimpleAdapter(this, jadwalRemix,R.layout.my_list,new String[] { "result"}, new int[] {R.id.txtResult});
setListAdapter(adapter);
}
}
还有这个 JSONParser
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
public JSONObject AmbilJson(String url) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "
");
}
is.close();
json = sb.toString();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
}
我在哪里可以放置 Asyntask 的代码?
Where can I put code for Asyntask?
好的，我得到了示例代码，我的代码现在是这样的
public class Jadwal_remix extends ListActivity {
String v_date;
JSONArray r_js = null;
ArrayList<HashMap<String, String>> myArray = new ArrayList<HashMap<String,String>>();
public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.main);
private class myProses extends AsyncTask<Void, Void, Void> {
ProgressDialog dialog;
protected void onPreExecute() {
dialog = ProgressDialog.show(Jadwal_remix.this, "", "Loading... Please wait", true);
}
protected Void doInBackground(Void... params) {
String status ="";
String date = "";
String result = "";
String url = "http://10.0.2.2/remix/view_list.php";
JSONParser jParser = new JSONParser();
JSONObject json = jParser.AmbilJson(url);
try
{
r_js = json.getJSONArray("view_list");
for (int i =0; i < r_js.length(); i++)
{
String my_array = "";
JSONObject ar = r_js.getJSONObject(i);
status = ar.getString("st");
date = ar.getString("date");
result = ar.getString("result");
if (status.trim().equals("er"))
{
my_array += "Sorry "+result;
HashMap<String, String> map = new HashMap<String, String>();
map.put("result", my_array);
myArray.add(map);
}
else
{
my_array += "Date : "+date+" "+"Result : "+result;
HashMap<String, String> map = new HashMap<String, String>();
map.put("result", my_array);
myArray.add(map);
}
}
}
catch (JSONException e)
{
e.printStackTrace();
}
return null;
protected void onPostExecute(Void unused) {
adapter_listview();
dialog.dismiss();
}
}
public void adapter_listview() {
ListAdapter adapter = new SimpleAdapter(this, jadwalRemix,R.layout.my_list,new String[] { "result"}, new int[] {R.id.txtResult});
setListAdapter(adapter);
}
}
我在服务器死机时遇到问题，它仍在加载.我如何显示消息例如:无法连接到服务器?
I'm get problem when server is die, it still loading. How I can show message ex: can't connect to server?
推荐答案
这是我的代码，请试试这个，
This is my code please try this one,
MAinActivity.java
MAinActivity.java
public class MyActivity extends Activity {
private ListView contests_listView;
private ProgressBar pgb;
ActivitiesBean bean;
ArrayList<Object> listActivities;
ActivityAdapter adapter;
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_listview);
contests_listView = (ListView) findViewById(R.id.activity_listView);
pgb = (ProgressBar) findViewById(R.id.contests_progressBar);
listActivities = new ArrayList<Object>();
new FetchActivitesTask().execute();
}
public class FetchActivitesTask extends AsyncTask<Void, Void, Void> {
int i =0;
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
pgb.setVisibility(View.VISIBLE);
}
@Override
protected Void doInBackground(Void... params) {
// TODO Auto-generated method stub
String url = "Your URL Here";
String strResponse = util.makeWebCall(url);
try {
JSONObject objResponse = new JSONObject(strResponse);
JSONArray jsonnodes = objResponse.getJSONArray(nodes);
for (i = 0; i < jsonnodes.length(); i++)
{
String str = Integer.toString(i);
Log.i("Value of i",str);
JSONObject jsonnode = jsonnodes.getJSONObject(i);
JSONObject jsonnodevalue = jsonnode.getJSONObject(node);
bean = new ActivitiesBean();
bean.title = jsonnodevalue.getString(title);
bean.image = jsonnodevalue.getString(field_activity_image_fid);
listActivities.add(bean);
}
}
catch (JSONException e) {
e.printStackTrace();
}
return null;
}
@Override
public void onPostExecute(Void result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
pgb.setVisibility(View.GONE);
displayAdapter();
}
}
public void displayAdapter()
{
adapter = new ActivityAdapter(this, listActivities);
contests_listView.setAdapter(adapter);
contests_listView.setOnItemClickListener(new OnItemClickListener() {
//@Override
public void onItemClick(AdapterView<?> arg0, View arg1,
int position, long id) {
// your onclick Activity
}
});
}
}
工具类
public static String makeWebCall(String url) {
DefaultHttpClient client = new DefaultHttpClient();
HttpGet httpRequest = new HttpGet(url);
// HttpPost post = new HttpPost(url);
try {
HttpResponse httpResponse = client.execute(httpRequest);
final int statusCode = httpResponse.getStatusLine().getStatusCode();
if (statusCode != HttpStatus.SC_OK) {
return null;
}
HttpEntity entity = httpResponse.getEntity();
InputStream instream = null;
if (entity != null) {
instream = entity.getContent();
}
return iStream_to_String(instream);
}
catch (IOException e) {
httpRequest.abort();
// Log.w(getClass().getSimpleName(), "Error for URL =>" + url, e);
}
return null;
}
public static String iStream_to_String(InputStream is1) {
BufferedReader rd = new BufferedReader(new InputStreamReader(is1), 4096);
String line;
StringBuilder sb = new StringBuilder();
try {
while ((line = rd.readLine()) != null) {
sb.append(line);
}
rd.close();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
String contentOfMyInputStream = sb.toString();
return contentOfMyInputStream;
}
}
ActivityBean.java
ActivityBean.java
public class ActivitiesBean implements Serializable{
/**
*
*/
private static final long serialVersionUID = 1L;
public String title;
public String image;
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getImage() {
return image;
}
public void setImage(String image) {
this.image = image;
}
这篇关于使用 Asynctask 在列表视图中显示数据的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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