Android JSON解析器性能低下

我在这里转载是为了得到一些帮助

我制作了一个JSON解析器，它返回一个JSONArray（以便从我的Web服务获取信息）

当我在IceScreamSandwich上测试NetworkException时，我的上一个代码抛出了一个NetworkException错误（在版本2.3.3上，它很长，但运行良好）

我更改了代码以停止它并尝试获得更好的性能。。但它仍然不能在我的ICS手机上工作：现在没有更多的错误，只有一个IOException：“无法读取JSON URL”

我向您展示我的活动：

public class TabNewsJSONParsingActivity extends ListActivity

{

}

谁知道如何获得更好的性能并使其成为4.0版的朗姆酒？ 如何将其用于异步任务？

---

谢谢

这可能是因为您在主线程上运行web连接。。尝试将这段代码运行到AsyncTask或其他线程中。

您需要使用AsyncTask下载和解析数据

代码如下

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.StrictMode;
import android.view.MenuItem;
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 TabNewsJSONParsingActivity extends ListActivity
{
    static{
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();

        StrictMode.setThreadPolicy(policy);
    }

    // url to make request
    private static String url = "http://developer.prixo.fr/API/GetEvents?zone=8";

    //JSON names
    private static final String TAG_content = "content";
    private static final String TAG_zone = "zone";
    private static final String TAG_id = "id";
    private static final String TAG_area = "area";
    private static final String TAG_title = "title";
    private static final String TAG_date = "date";
    private static final String TAG_author = "author";

    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.onglet_news);



        // selecting single ListView item
        ListView lv = getListView();

        // Launching new screen on Selecting Single ListItem
        lv.setOnItemClickListener(new OnItemClickListener() 
        {
            public void onItemClick(AdapterView<?> parent, View view,int position, long id) {
                // getting values from selected ListItem
                String name = ((TextView) view.findViewById(R.id.name)).getText().toString();
                String cost = ((TextView) view.findViewById(R.id.email)).getText().toString();
                String description = ((TextView) view.findViewById(R.id.mobile)).getText().toString();

                // Starting new intent
                Intent in = new Intent(getApplicationContext(), TabNewsSingleMenuItemActivity.class);
                in.putExtra(TAG_content, name);
                in.putExtra(TAG_title, cost);
                in.putExtra(TAG_author, description);
                startActivity(in);

            }
        });

        new DownloadData().execute();
    }

    public boolean onOptionsItemSelected(MenuItem item) 
    {   
       //On regarde quel item a été cliqué grâce à son id et on déclenche une action
       switch (item.getItemId()) 
       {
          case R.id.credits:
             //pop up
            Toast.makeText(TabNewsJSONParsingActivity.this, "Un delire", Toast.LENGTH_SHORT).show();
             return true;
          case R.id.quitter:
             //Pour fermer l'application il suffit de faire finish()
             finish();
             return true;
       }
     return false;  
    }


    private class DownloadData extends AsyncTask<Void, Integer, ArrayList<HashMap<String, String>>>
    {
        ProgressDialog pd = null;
        /* (non-Javadoc)
         * @see android.os.AsyncTask#onPreExecute()
         */
        @Override
        protected void onPreExecute() {
            // TODO Auto-generated method stub
            super.onPreExecute();

            pd = new ProgressDialog(TabNewsJSONParsingActivity.this);
            pd.setTitle("Downloading...");
            pd.setMessage("Please wait...");
            pd.setCancelable(false);
            pd.show();
        }

        /* (non-Javadoc)
         * @see android.os.AsyncTask#doInBackground(Params[])
         */
        @Override
        protected ArrayList<HashMap<String, String>> doInBackground(Void... params) {
            // TODO Auto-generated method stub

            // Hashmap for ListView
            ArrayList<HashMap<String, String>> newsList = new ArrayList<HashMap<String, String>>();

            // Creating JSON Parser instance
            JSONParser jParser = new JSONParser();

            // getting JSON string from URL
            JSONArray json;
            try {
                json = jParser.getJSONFromUrl1(url);

                        for(int i=0; i < json.length(); i++)
                        {
                            JSONObject child = json.getJSONObject(i);

                            String id = child.getString(TAG_id);
                            String title = child.getString(TAG_title);
                            String content = child.getString(TAG_content);
                            String date = child.getString(TAG_date);
                            String author = child.getString(TAG_author);
                            String zone = child.getString(TAG_zone);
                            String area = child.getString(TAG_area);


                            // creating new HashMap
                            HashMap<String, String> map = new HashMap<String, String>();

                            // adding each child node to HashMap key => value
                            map.put(TAG_content, content);
                            map.put(TAG_title, title);
                            map.put(TAG_author, author);

                            // adding HashList to ArrayList
                            newsList.add(map);
                        }
                    }
                catch (JSONException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

            return newsList;
        }

        /* (non-Javadoc)
         * @see android.os.AsyncTask#onPostExecute(java.lang.Object)
         */
        @Override
        protected void onPostExecute(ArrayList<HashMap<String, String>> newsList) {
            // TODO Auto-generated method stub
            super.onPostExecute(newsList);
            pd.dismiss();

            /**
             * Updating parsed JSON data into ListView
             * */
            ListAdapter adapter = new SimpleAdapter(TabNewsJSONParsingActivity.this, newsList,R.layout.onglet_news_listitem,new String[] { TAG_content, TAG_title, TAG_author }, new int[] {R.id.name, R.id.email, R.id.mobile });
            TabNewsJSONParsingActivity.this.setListAdapter(adapter);


        }

    }
}

import java.io.IOException；
导入java.util.ArrayList；
导入java.util.HashMap；
导入org.json.JSONArray；
导入org.json.JSONException；
导入org.json.JSONObject；
导入android.app.ListActivity；
导入android.app.ProgressDialog；
导入android.content.Intent；
导入android.os.AsyncTask；
导入android.os.Bundle；
导入android.os.StrictMode；
导入android.view.MenuItem；
导入android.view.view；
导入android.widget.AdapterView；
导入android.widget.AdapterView.OnItemClickListener；
导入android.widget.ListAdapter；
导入android.widget.ListView；
导入android.widget.simpledapter；
导入android.widget.TextView；
导入android.widget.Toast；
公共类选项卡NewsJSonParsingActivity扩展了ListActivity
{
静止的{
StrictMode.ThreadPolicy policy=新建StrictMode.ThreadPolicy.Builder（）.permitAll（）.build（）；
StrictMode.setThreadPolicy（策略）；
}
//发出请求的url
专用静态字符串url=”http://developer.prixo.fr/API/GetEvents?zone=8";
//JSON名称
私有静态最终字符串标记_content=“content”；
私有静态最终字符串标记_zone=“zone”；
私有静态最终字符串标记\u id=“id”；
私有静态最终字符串标记_area=“area”；
私有静态最终字符串标记_title=“title”；
私有静态最终字符串标记_date=“date”；
私有静态最终字符串标记\u author=“author”；
@凌驾
创建时的公共void（Bundle savedInstanceState）
{
super.onCreate（savedInstanceState）；
setContentView（R.layout.onglet_新闻）；
//选择单个ListView项
ListView lv=getListView（）；
//在选择单个列表项时启动新屏幕
lv.setOnItemClickListener（新的OnItemClickListener（）
{
public void onItemClick（AdapterView父对象、视图、整型位置、长id）{
//从选定的ListItem获取值
字符串名称=（（TextView）view.findviewbyd（R.id.name））.getText（）.toString（）；
字符串成本=（（TextView）view.findViewById（R.id.email））.getText（）.toString（）；
字符串描述=（（TextView）view.findviewbyd（R.id.mobile））.getText（）.toString（）；
//开始新的意图
Intent in=new Intent（getApplicationContext（），TabNewsSingleMenuItemActivity.class）；
in.putExtra（标签内容、名称）；
额外费用（标签名称、成本）；
in.putExtra（标记作者，描述）；
星触觉（in）；
}
});
新建下载数据（）.execute（）；
}
公共布尔值onOptionsItemSelected（菜单项项）
{   
//关于regarde quel物品aétécliquégréceáson id和déclenche une action
开关（item.getItemId（））
{
案例R.id.学分：
//弹出
Toast.makeText（TabNewsJSONParsingActivity.this，“undelire”，Toast.LENGTH_SHORT.show（）；
返回true；
案例R.id.退出者：
//浇注fermer l'涂料，以满足表面光洁度要求（）
完成（）；
返回true；
}
返回false；
}
私有类下载数据扩展异步任务
{
ProgressDialog pd=null；
/*（非Javadoc）
*@see android.os.AsyncTask#onPreExecute（）
*/
@凌驾
受保护的void onPreExecute（）{
//TODO自动生成的方法存根
super.onPreExecute（）；
pd=新建进度对话框（选项卡newsJSonParsingActivity.this）；
pd.setTitle（“下载…”）；
设置消息（“请稍候…”）；
pd.可设置可取消（假）；
pd.show（）；
}
/*（非Javadoc）
*@see android.os.AsyncTask#doInBackground（Params[]）
*/
@凌驾
受保护的ArrayList doInBackground（无效…参数）{
//TODO自动生成的方法存根
//ListView的Hashmap
ArrayList newsList=新建ArrayList（）；
//创建JSON解析器实例
JSONParser jParser=新的JSONParser（）；
//从URL获取JSON字符串
JSONArray-json；
试一试{
json=jParser.getJSONFromUrl1（url）；
for（int i=0；ivalue
地图放置(
static InputStream is = null;
static JSONObject jObj = null;
static String jsonstr = "";

public JSONParser() {}

 // throws IOException just to tell the caller that something bad happened (and 
 // what) instead of simply returning 'null' without any more information.
 public JSONArray getJSONFromUrl1(String url) throws IOException 
 {
     try 
     {
         // should be a member of the parser to allow multiple calls without recreating the client every time.
         DefaultHttpClient httpClient = new DefaultHttpClient();
         // Using POST means sending data (or it its not following HTTP RFCs)
         //HttpPost httpPost = new HttpPost(url);
         HttpGet httpGet = new HttpGet(url);

         // Here the client may not be entirely initialized (no timeout, no agent-string).
         HttpResponse httpResponse = httpClient.execute(httpGet);
         //HttpResponse httpResponse = httpClient.execute(httpPost);

         HttpEntity httpEntity = httpResponse.getEntity();

         // The native utility function is also handling other charsets
         String httpString = EntityUtils.toString(httpEntity);

         return new JSONArray(httpString);
     } catch (IOException ioe) {
     throw ioe;
     } catch (Exception ex) {
     throw new IOException("Failed to read JSON from Url");
     }
 }

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.StrictMode;
import android.view.MenuItem;
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 TabNewsJSONParsingActivity extends ListActivity
{
    static{
        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();

        StrictMode.setThreadPolicy(policy);
    }

    // url to make request
    private static String url = "http://developer.prixo.fr/API/GetEvents?zone=8";

    //JSON names
    private static final String TAG_content = "content";
    private static final String TAG_zone = "zone";
    private static final String TAG_id = "id";
    private static final String TAG_area = "area";
    private static final String TAG_title = "title";
    private static final String TAG_date = "date";
    private static final String TAG_author = "author";

    @Override
    public void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.onglet_news);



        // selecting single ListView item
        ListView lv = getListView();

        // Launching new screen on Selecting Single ListItem
        lv.setOnItemClickListener(new OnItemClickListener() 
        {
            public void onItemClick(AdapterView<?> parent, View view,int position, long id) {
                // getting values from selected ListItem
                String name = ((TextView) view.findViewById(R.id.name)).getText().toString();
                String cost = ((TextView) view.findViewById(R.id.email)).getText().toString();
                String description = ((TextView) view.findViewById(R.id.mobile)).getText().toString();

                // Starting new intent
                Intent in = new Intent(getApplicationContext(), TabNewsSingleMenuItemActivity.class);
                in.putExtra(TAG_content, name);
                in.putExtra(TAG_title, cost);
                in.putExtra(TAG_author, description);
                startActivity(in);

            }
        });

        new DownloadData().execute();
    }

    public boolean onOptionsItemSelected(MenuItem item) 
    {   
       //On regarde quel item a été cliqué grâce à son id et on déclenche une action
       switch (item.getItemId()) 
       {
          case R.id.credits:
             //pop up
            Toast.makeText(TabNewsJSONParsingActivity.this, "Un delire", Toast.LENGTH_SHORT).show();
             return true;
          case R.id.quitter:
             //Pour fermer l'application il suffit de faire finish()
             finish();
             return true;
       }
     return false;  
    }


    private class DownloadData extends AsyncTask<Void, Integer, ArrayList<HashMap<String, String>>>
    {
        ProgressDialog pd = null;
        /* (non-Javadoc)
         * @see android.os.AsyncTask#onPreExecute()
         */
        @Override
        protected void onPreExecute() {
            // TODO Auto-generated method stub
            super.onPreExecute();

            pd = new ProgressDialog(TabNewsJSONParsingActivity.this);
            pd.setTitle("Downloading...");
            pd.setMessage("Please wait...");
            pd.setCancelable(false);
            pd.show();
        }

        /* (non-Javadoc)
         * @see android.os.AsyncTask#doInBackground(Params[])
         */
        @Override
        protected ArrayList<HashMap<String, String>> doInBackground(Void... params) {
            // TODO Auto-generated method stub

            // Hashmap for ListView
            ArrayList<HashMap<String, String>> newsList = new ArrayList<HashMap<String, String>>();

            // Creating JSON Parser instance
            JSONParser jParser = new JSONParser();

            // getting JSON string from URL
            JSONArray json;
            try {
                json = jParser.getJSONFromUrl1(url);

                        for(int i=0; i < json.length(); i++)
                        {
                            JSONObject child = json.getJSONObject(i);

                            String id = child.getString(TAG_id);
                            String title = child.getString(TAG_title);
                            String content = child.getString(TAG_content);
                            String date = child.getString(TAG_date);
                            String author = child.getString(TAG_author);
                            String zone = child.getString(TAG_zone);
                            String area = child.getString(TAG_area);


                            // creating new HashMap
                            HashMap<String, String> map = new HashMap<String, String>();

                            // adding each child node to HashMap key => value
                            map.put(TAG_content, content);
                            map.put(TAG_title, title);
                            map.put(TAG_author, author);

                            // adding HashList to ArrayList
                            newsList.add(map);
                        }
                    }
                catch (JSONException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

            return newsList;
        }

        /* (non-Javadoc)
         * @see android.os.AsyncTask#onPostExecute(java.lang.Object)
         */
        @Override
        protected void onPostExecute(ArrayList<HashMap<String, String>> newsList) {
            // TODO Auto-generated method stub
            super.onPostExecute(newsList);
            pd.dismiss();

            /**
             * Updating parsed JSON data into ListView
             * */
            ListAdapter adapter = new SimpleAdapter(TabNewsJSONParsingActivity.this, newsList,R.layout.onglet_news_listitem,new String[] { TAG_content, TAG_title, TAG_author }, new int[] {R.id.name, R.id.email, R.id.mobile });
            TabNewsJSONParsingActivity.this.setListAdapter(adapter);


        }

    }
}

JSONTask g = new JSONTask();
g.execute();

public abstract class JSONTask extends AsyncTask<String, Void, String> {
@Override
protected String doInBackground(String... arg) {
  //Do http get json here
  String htpStatus= "";
  String httpJSON = "" // this is the json data from you web service

  // Create here your JSONObject...
  JSONObject json = new JSONObject(httpJSON);
  for(int i=0; i < json.length(); i++){
                JSONObject child = json.getJSONObject(i);

                String id = child.getString(TAG_id);
                String title = child.getString(TAG_title);
                String content = child.getString(TAG_content);
                String date = child.getString(TAG_date);
                String author = child.getString(TAG_author);
                String zone = child.getString(TAG_zone);
                String area = child.getString(TAG_area);


                // creating new HashMap
                HashMap<String, String> map = new HashMap<String, String>();

                // adding each child node to HashMap key => value
                map.put(TAG_content, content);
                map.put(TAG_title, title);
                map.put(TAG_author, author);

                // adding HashList to ArrayList
                newsList.add(map);
  }
  return htpStatus; // This value will be returned to your onPostExecute(result) method
}

@Override
protected void onPostExecute(String result) {

}
}