我在不使用异步任务的情况下完成了JSON解析，它在姜饼中运行良好（2.3） 但是当我在ICS（冰淇淋三明治）上运行相同的项目应用程序崩溃时，我听到某个地方我将不得不在asynctask中进行解析但我不熟悉android并且无法做到这一点可以有人帮助我... .........
这是我的JSON课程： -
public class JSONfunctions {
public static JSONObject getJSONfromURL(String url){
InputStream is = null;
String result = "";
JSONObject jArray = null;
//http post
try{
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost(url);
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
}catch(Exception e){
Log.e("log_tag", "Error in http connection "+e.toString());
}
//convert response to string
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 + "\n");
}
is.close();
result=sb.toString();
}catch(Exception e){
Log.e("log_tag", "Error converting result "+e.toString());
}
try{
jArray = new JSONObject(result);
}catch(JSONException e){
Log.e("log_tag", "Error parsing data "+e.toString());
}
return jArray;
}
}
这是我使用JSON类的MAinActivity： -
public class MainActivity extends ListActivity {
Context context;
ArrayList<String> contentList,slugList;
ArrayList<HashMap<String, String>> mylist;
JSONObject json;
JSONArray latest;
ImageView bck;
String shareUrl;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.listplaceholder);
bck = (ImageView) findViewById(R.id.bckbtn);
mylist = new ArrayList<HashMap<String, String>>();
contentList=new ArrayList<String>();
slugList=new ArrayList<String>();
json = JSONfunctions.getJSONfromURL("http://madhuridixit-nene.com/wp/?json=get_category_posts&slug=latest");
context=this;
try{
latest = json.getJSONArray("posts");
for(int i=0;i<latest.length();i++){
HashMap<String, String> map = new HashMap<String, String>();
JSONObject e = latest.getJSONObject(i);
String name = e.getString("title_plain");
String content = e.getString("content");
contentList.add(content);
String chng = "–";
String fnl_Str = name.replace(chng, "");
String slug = e.getString("slug");
slugList.add(slug);
map.put("id", String.valueOf(i));
map.put("name", fnl_Str);
map.put("date", e.getString("date"));
shareUrl ="http://madhuridixit-nene.com/latest/post/";
mylist.add(map);
}
}catch(JSONException e) {
Log.e("log_tag", "Error parsing data "+e.toString());
}
ListAdapter adapter = new SimpleAdapter(this, mylist , R.layout.activity_latest_tab,
new String[] { "name"},
new int[] { R.id.item_title});
setListAdapter(adapter);
final ListView lv = getListView();
lv.setTextFilterEnabled(true);
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
/* HashMap<String, String> o = (HashMap<String, String>) lv.getItemAtPosition(position); */
//Toast.makeText(Main.this, "ID '" + o.get("id") + "' was clicked.", Toast.LENGTH_SHORT).show();
Intent intent=new Intent(context,WebViewActivity.class);
intent.putExtra("content", contentList.get(position));
intent.putExtra("shareUrl", shareUrl+slugList.get(position));
intent.putExtra("tab_value", 1);
startActivity(intent);
}
});
}
PLZ帮助我使用AsyncTask .......
答案 0 :(得分：1)
更改代码使用AsyncTask和从服务器获取数据：
private class LongOperation extends AsyncTask<String, Void,
ArrayList<HashMap<String, String>>> {
ArrayList<String> contentList,slugList;
ArrayList<HashMap<String, String>> mylist;
JSONObject json;
JSONArray latest;
@Override
protected void onPreExecute() {
}
@Override
protected ArrayList<HashMap<String, String>>
doInBackground(String... params) {
mylist = new ArrayList<HashMap<String, String>>();
contentList=new ArrayList<String>();
slugList=new ArrayList<String>();
json = JSONfunctions.getJSONfromURL("http://madhuridixit-nene.com"+
"/wp/?json=get_category_posts&slug=latest");
try{
latest = json.getJSONArray("posts");
for(int i=0;i<latest.length();i++){
HashMap<String, String> map = new HashMap<String, String>();
JSONObject e = latest.getJSONObject(i);
String name = e.getString("title_plain");
String content = e.getString("content");
contentList.add(content);
String chng = "–";
String fnl_Str = name.replace(chng, "");
String slug = e.getString("slug");
slugList.add(slug);
map.put("id", String.valueOf(i));
map.put("name", fnl_Str);
map.put("date", e.getString("date"));
shareUrl ="http://madhuridixit-nene.com/latest/post/";
mylist.add(map);
}
}catch(JSONException e) {
Log.e("log_tag", "Error parsing data "+e.toString());
}
return mylist;
}
@Override
protected void onPostExecute(
ArrayList<HashMap<String, String>> result) {
ListAdapter adapter = new SimpleAdapter(this, result ,
R.layout.activity_latest_tab,
new String[] { "name"},
new int[] { R.id.item_title});
setListAdapter(adapter);
final ListView lv = getListView();
lv.setTextFilterEnabled(true);
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent,
View view, int position, long id) {
Intent intent=new Intent(MainActivity.this,WebViewActivity.class);
intent.putExtra("content", contentList.get(position));
intent.putExtra("shareUrl", shareUrl+slugList.get(position));
intent.putExtra("tab_value", 1);
startActivity(intent);
}
});
}
@Override
protected void onProgressUpdate(Void... values) {
}
}
从Activity的onCreate执行AsyncTask：
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.listplaceholder);
bck = (ImageView) findViewById(R.id.bckbtn);
new LongOperation().execute(""); // execute here
// your code here.....
最后你必须从这里阅读有关AsyncTask以供下次使用的内容
http://developer.android.com/reference/android/os/AsyncTask.html
答案 1 :(得分：0)
问题不在于解析json数据。这里的问题是您一直在尝试在Main thread上建立网络连接。网络连接是长任务，应该在单独的线程中运行。你在这里要做的基本上是你的
json = JSONfunctions.getJSONfromURL("http://madhuridixit-nene.com/wp/?json=get_category_posts&slug=latest");
在AsyncTask中排队 我希望这有帮助！
答案 2 :(得分：0)
首先，考虑在Android中遇到问题/获取异常时发布Logcat输出。
现在，您当前的异常是 NetworkOnMainThreadException ，这只是因为您正在主线程上直接进行Web调用。
从Android 3.0开始，Android宣布你无法直接在主线程上进行。
要解决此问题，您可以在进行网络通话之前实施 AsyncTask 或记下以下代码：
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
答案 3 :(得分：0)
是的，最后我感谢所有的想法......
我为asynctask创建了另一个类，如下所示： -
类MyAsyncTask扩展了AsyncTask＆gt; ＆GT; { 的ArrayList＆GT; mylist = new ArrayList＆gt;（）;
@Override
protected ArrayList<HashMap<String, String>> doInBackground(
String... params) {
// TODO Auto-generated method stub
mylist = new ArrayList<HashMap<String, String>>();
contentList=new ArrayList<String>();
slugList=new ArrayList<String>();
json = JSONfunctions.getJSONfromURL("http://madhuridixit-nene.com/wp/?json=get_category_posts&slug=latest");
try{
latest = json.getJSONArray("posts");
for(int i=0;i<latest.length();i++){
HashMap<String, String> map = new HashMap<String, String>();
JSONObject e = latest.getJSONObject(i);
String name = e.getString("title_plain");
String content = e.getString("content");
contentList.add(content);
String chng = "–";
String fnl_Str = name.replace(chng, "");
String slug = e.getString("slug");
slugList.add(slug);
map.put("id", String.valueOf(i));
map.put("name", fnl_Str);
map.put("date", e.getString("date"));
shareUrl ="http://madhuridixit-nene.com/latest/post/";
mylist.add(map);
}
}catch(JSONException e) {
Log.e("log_tag", "Error parsing data "+e.toString());
}
showProgress.setVisibility(View.VISIBLE);
return mylist;
}
@Override
protected void onPostExecute(ArrayList<HashMap<String, String>> result) {
ListAdapter adapter = new SimpleAdapter(LAtestTab.this, result , R.layout.activity_latest_tab,
new String[] { "name" },
new int[] { R.id.item_title});
LAtestTab.this.setListAdapter(adapter);// If Activity extends ListActivity
final ListView lv = getListView();
lv.setTextFilterEnabled(true);
showProgress.setVisibility(View.GONE);
lv.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Intent intent=new Intent(context,WebViewActivity.class);
intent.putExtra("content", contentList.get(position));
intent.putExtra("shareUrl", shareUrl+slugList.get(position));
intent.putExtra("tab_value", 1);
startActivity(intent);
}
});
}
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
showProgress.setVisibility(View.VISIBLE);
}
@Override
protected void onProgressUpdate(Integer... values) {
// TODO Auto-generated method stub
super.onProgressUpdate(values);
showProgress.setVisibility(View.VISIBLE);
}
}