Android JSON解析器错误：http客户端失败

我正在学习JSON解析器。我遵循androidhive教程并复制其代码，但遗憾的是，我不能。它不显示任何内容，并且存在以下类型的错误：

 11-22 17:27:12.132: E/AndroidRuntime(1938): Caused by: android.os.NetworkOnMainThreadException

有人能帮我解决这个问题吗？谢谢

杰森帕瑟

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONException;
import org.json.JSONObject;

import android.util.Log;

public class JSONParser {

    static InputStream is = null;
    static JSONObject jObj = null;
    static String json = "";

    // constructor
    public JSONParser() {

    }

    public JSONObject getJSONFromUrl(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 + "\n");
            }
            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;

    }
}

主要活动

import android.view.Menu;

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.content.Intent;
import android.os.Bundle;
import android.util.Log;
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;


public class MainActivity extends ListActivity{
    // 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
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

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

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

                // getting JSON string from URL
                JSONObject json = jParser.getJSONFromUrl(url);

                try {
                    // Getting Array of Contacts
                    contacts = json.getJSONArray(TAG_CONTACTS);

                    // looping through All Contacts
                    for(int i = 0; i < contacts.length(); i++){
                        JSONObject c = contacts.getJSONObject(i);

                        // Storing each json item in variable
                        String id = c.getString(TAG_ID);
                        String name = c.getString(TAG_NAME);
                        String email = c.getString(TAG_EMAIL);
                        String address = c.getString(TAG_ADDRESS);
                        String gender = c.getString(TAG_GENDER);

                        // Phone number is agin JSON Object
                        JSONObject phone = c.getJSONObject(TAG_PHONE);
                        String mobile = phone.getString(TAG_PHONE_MOBILE);
                        String home = phone.getString(TAG_PHONE_HOME);
                        String office = phone.getString(TAG_PHONE_OFFICE);

                        // 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);
                        map.put(TAG_EMAIL, email);
                        map.put(TAG_PHONE_MOBILE, mobile);

                        // adding HashList to ArrayList
                        contactList.add(map);
                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }


                /**
                 * Updating parsed JSON data into ListView
                 * */
                ListAdapter adapter = new SimpleAdapter(this, contactList,
                        R.layout.list_item,
                        new String[] { TAG_NAME, TAG_EMAIL, TAG_PHONE_MOBILE }, new int[] {
                                R.id.name, R.id.email, R.id.mobile });

                setListAdapter(adapter);

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

                // Launching new screen on Selecting Single ListItem
                lv.setOnItemClickListener(new OnItemClickListener() {

                    @Override
                    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(), SingleMenuItemActivity.class);
                        in.putExtra(TAG_NAME, name);
                        in.putExtra(TAG_EMAIL, cost);
                        in.putExtra(TAG_PHONE_MOBILE, description);
                        startActivity(in);

                    }
                });


            }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

}

}

---

在这段代码中，LogCat捕获我的第二次尝试并打印日志\u connect，http连接中出现错误

您有一个NetworkOnMainThreadException错误

这意味着您已经在onCreate方法上直接运行了代码：

但是您不能直接在MainUI线程上更新数据

为此，您必须使用AsyncTask或带处理程序的线程，或使用runOnUiThread（）更新您的UI

你可以这样做：

---

您是否读取了堆栈跟踪

原因：android.os.NetworkOnMainThreadException

如果你在谷歌上搜索“NetworkOnMainThreadException”，你就会得到答案

简而言之，原因是您正在主线程上执行HTTP请求，这实际上是一个糟糕的做法。Android最近变得更加严格，并抛出了一个例外

你需要的是这样的东西：

new AsyncTask<CustomParamClass, Void, String>() {
    @Override
    protected String doInBackground(final CustomerParamClass... params) {
        //use params to get the data and make an HHTP Request.
    }

    @Override
    protected void onPostExecute(final String params) {
        // This is invoked on the main thread. Communicate here.
    }
}.execute(<pass some params here>);

newasynctask（）{
@凌驾
受保护字符串doInBackground（最终CustomerParamClass…参数）{
//使用params获取数据并发出HHTP请求。
}
@凌驾
受保护的void onPostExecute（最终字符串参数）{
//这是在主线程上调用的。在此处通信。
}
}.execute（）；

sry我是android的新手，上个月刚开始学习。但是我应该把这个方法放在哪里？？main类或JSON解析器类您应该将此方法放在可以执行此类的主类中。为了改进您的问题，最好显示

代码
。。你是如何得到错误的，你已经尝试了什么，你曾经做过的教程的链接。。很抱歉，我不明白离题的意思。我是新手，在没有适当指导的情况下学习android，我无法定义问题。请原谅我的愚蠢，帮我解决这个问题谢谢
new AsyncTask<CustomParamClass, Void, String>() {
    @Override
    protected String doInBackground(final CustomerParamClass... params) {
        //use params to get the data and make an HHTP Request.
    }

    @Override
    protected void onPostExecute(final String params) {
        // This is invoked on the main thread. Communicate here.
    }
}.execute(<pass some params here>);