java - JSON 解析中的异步任务

Question

这是我的示例代码，我在其中创建了一个 json 解析类来解析来自给定链接的数据。

package com.billosuch.listviewblogpost;

import java.util.ArrayList;

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

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.ListView;

public class ListViewBlogPost extends Activity {

    // url to make request
    private static String url = "http://api.androidhive.info/contacts/";

    // JSON Node names
    private static final String TAG_CONTACTS = "contacts";
    private static final String TAG_ID = "id";
    private static final String TAG_NAME = "name";
    private static final String TAG_EMAIL = "email";
    private static final String TAG_ADDRESS = "address";
    private static final String TAG_GENDER = "gender";
    private static final String TAG_PHONE = "phone";
    private static final String TAG_PHONE_MOBILE = "mobile";
    private static final String TAG_PHONE_HOME = "home";
    private static final String TAG_PHONE_OFFICE = "office";

    // contacts JSONArray
    JSONArray contacts = null;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        ArrayList<SearchResults> searchResultss = new ArrayList<SearchResults>();
        final ListView lv1 = (ListView) findViewById(R.id.ListView01);

        JSONParser jparser = new JSONParser();
        JSONObject json = jparser.getJSONFromUrl(url);

        // looping through All Contacts

        Log.d("*********oSR", "B4 TRy");

        try {

            contacts = json.getJSONArray(TAG_CONTACTS);

            for (int i = 0; i < contacts.length(); i++) {

                SearchResults oSR = new SearchResults();
                JSONObject c = contacts.getJSONObject(i);

                oSR.setId(c.getString(TAG_ID));
                oSR.setName(c.getString(TAG_NAME));
                oSR.setEmail(c.getString(TAG_EMAIL));
                oSR.setAddress(c.getString(TAG_ADDRESS));
                oSR.setGender(c.getString(TAG_GENDER));

                JSONObject phone = c.getJSONObject(TAG_PHONE);

                oSR.setPhone_mobile(phone.getString(TAG_PHONE_MOBILE));
                oSR.setPhone_home(phone.getString(TAG_PHONE_HOME));
                oSR.setPhone_office(phone.getString(TAG_PHONE_OFFICE));

                searchResultss.add(oSR);

                Log.d("*********oSR", oSR.getName());

            }
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        Log.d("*********oSR", "AFTER TRy");
        lv1.setAdapter(new MyCustomBaseAdapter(this, searchResultss));

    }


}

此代码向我显示在 Asyntask 中执行此操作的警告。我希望 ICS 和 JellyBean 支持它。

Skipped 391 frames!  The application may be doing too much work on its main thread.

Answer 1

为此您应该使用异步任务并将与网络相关的代码移至 doinBackground()

http://developer.android.com/reference/android/os/AsyncTask.html .

在 UI 线程上加载异步任务

  new TheTask().execute()

异步任务类。

  class TheTask extends AsyncTask<Void,Void,Void>
  {
  protected void onPreExecute()
  {           super.onPreExecute();
            //display progressdialog.
  } 

   protected void doInBackground(Void ...params)
  {  
        //Network related opearaiton. Do not update ui here

        return null;
  } 

   protected void onPostExecute(Void result)
  {     
            super.onPostExecute(result);
            //dismiss progressdialog.
            //update ui
  } 

 }

您可以将 URL 传递给异步任务的构造函数或直接传递给 doInbackground()