Android-Json解析器無法顯示從後端檢索到的數據

Question

我是android新手。我正在實現一個項目，我想從後端獲取數據並顯示在我的android屏幕上。

我試圖調用JSON是： -

[{"admin":null,"card_no":"8789","created_at":"2013-04-09T12:55:54Z","deleted":0,"email":"dfds@fgfd.com","entered_by":null,"first_name":"Gajanan","id":8,"last_name":"Bhat","last_updated_by":null,"middle_name":"","mobile":87981,"updated_at":"2013-04-13T05:26:25Z","user_type_id":null},{"admin":{"created_at":"2013-04-10T09:02:00Z","deleted":0,"designation":"Sr software Engineer","email":"admin@qwe.com","first_name":"Chiron","id":1,"last_name":"Synergies","middle_name":"Sr software Engineer","office_phone":"98789765","super_admin":false,"updated_at":"2013-04-10T12:03:04Z","username":"Admin"},"card_no":"66","created_at":"2013-04-08T09:47:15Z","deleted":0,"email":"rajaarun1991","entered_by":1,"first_name":"Arun","id":1,"last_name":"Raja\n","last_updated_by":1,"middle_name":"Nagaraj","mobile":941,"updated_at":"2013-04-08T09:47:15Z","user_type_id":1}] 

我JsonParser.java如下： -

package com.example.library; 

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.StatusLine; 
import org.apache.http.client.ClientProtocolException; 
import org.apache.http.client.HttpClient; 
import org.apache.http.client.methods.HttpGet; 
import org.apache.http.impl.client.DefaultHttpClient; 
import org.apache.http.util.EntityUtils; 
import org.json.JSONArray; 
import org.json.JSONException; 
import org.json.JSONObject; 

import android.util.Log; 


import android.util.Log; 

public class JSONParser { 

static InputStream is = null; 
static JSONArray jarray = null; 
static String json = ""; 

// constructor 
public JSONParser() { 

} 

public JSONArray getJSONFromUrl(String url) { 

    StringBuilder builder = new StringBuilder(); 
    HttpClient client = new DefaultHttpClient(); 
    HttpGet httpGet = new HttpGet(url); 
    try { 
    HttpResponse response = client.execute(httpGet); 
    StatusLine statusLine = response.getStatusLine(); 
    int statusCode = statusLine.getStatusCode(); 
    if (statusCode == 200) { 
     HttpEntity entity = response.getEntity(); 
     InputStream content = entity.getContent(); 
     BufferedReader reader = new BufferedReader(new InputStreamReader(content)); 
     String line; 
     while ((line = reader.readLine()) != null) { 
     builder.append(line); 
     } 
    } else { 
     Log.e("==>", "Failed to download file"); 
    } 
    } catch (ClientProtocolException e) { 
    e.printStackTrace(); 
    } catch (IOException e) { 
    e.printStackTrace(); 
    } 

// try parse the string to a JSON object 
try { 
jarray = new JSONArray(builder.toString()); 
} catch (JSONException e) { 
Log.e("JSON Parser", "Error parsing data " + e.toString()); 
} 

// return JSON String 
return jarray; 

} 
} 
    /* public void writeJSON() { 
      JSONObject object = new JSONObject(); 
      try { 
      object.put("name", ""); 
      object.put("score", new Integer(200)); 
      object.put("current", new Double(152.32)); 
      object.put("nickname", "Programmer"); 
      } catch (JSONException e) { 
      e.printStackTrace(); 
      } 
      System.out.println(object); 
     } 
*/ 

而我activity.java如下： -

package com.example.library; 

import java.util.ArrayList; 
import java.util.HashMap; 
import java.util.List; 
import java.util.Map; 

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



import android.app.Activity; 
import android.app.ListActivity; 
import android.app.ProgressDialog; 
import android.content.Context; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.util.Log; 
import android.widget.ListAdapter; 
import android.widget.ListView; 
import android.widget.SimpleAdapter; 


public class SecondActivity extends Activity 
{ 
    private Context context; 
    private static String url = "http://192.168.0.100:3000/users.json"; 

    private static final String TAG_ID = "id"; 
    private static final String TAG_FIRST_NAME = "first_name"; 
    private static final String TAG_MIDDLE_NAME = "middle_name"; 
    private static final String TAG_LAST_NAME = "last_name"; 

    // private static final String TAG_POINTS = "experiencePoints"; 

    ArrayList<HashMap<String, String>> jsonlist = new ArrayList<HashMap<String, String>>(); 

    ListView lv ; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    new ProgressTask(SecondActivity.this).execute(); 
    } 

    private class ProgressTask extends AsyncTask<String, Void, Boolean> { 
    private ProgressDialog dialog; 

    public ProgressTask(SecondActivity secondActivity) { 

    Log.i("1", "Called"); 
    context = secondActivity; 
    dialog = new ProgressDialog(context); 
    } 

    /** progress dialog to show user that the backup is processing. */ 

    /** application context. */ 
    private Context context; 

    protected void onPreExecute() { 
    this.dialog.setMessage("Progress start"); 
    this.dialog.show(); 
    } 

    @Override 
    protected void onPostExecute(final Boolean success) { 
    if (dialog.isShowing()) { 
    dialog.dismiss(); 
    } 
    ListAdapter adapter = new SimpleAdapter(context, jsonlist, 
    R.layout.list_item, new String[] { TAG_ID, TAG_FIRST_NAME, 
    TAG_MIDDLE_NAME, TAG_LAST_NAME }, new int[] { 
    R.id.id, R.id.first_name, R.id.middle_name, 
    R.id.last_name }); 

    setListAdapter(adapter); 

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






    } 

    private void setListAdapter(ListAdapter adapter) { 
     // TODO Auto-generated method stub 

    } 

    protected Boolean doInBackground(final String... args) { 

    JSONParser jParser = new JSONParser(); 

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

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

    try { 
    JSONObject c = json.getJSONObject(i); 
    String id = c.getString(TAG_ID); 

    String first_name = c.getString(TAG_FIRST_NAME); 
    String middle_name = c.getString(TAG_MIDDLE_NAME); 
    String last_name = c.getString(TAG_LAST_NAME); 

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

    // adding each child node to HashMap key => value 
    map.put(TAG_ID, id); 
    map.put(TAG_FIRST_NAME, first_name); 
    map.put(TAG_MIDDLE_NAME, middle_name); 
    map.put(TAG_LAST_NAME, last_name); 
    jsonlist.add(map); 
    } catch (JSONException e) { 
    // TODO Auto-generated catch block 
    e.printStackTrace(); 
    } 
    } 

    return null; 

    } 
    } 

    public ListView getListView() { 
     // TODO Auto-generated method stub 
     return null; 
    } 
} 

我無法在用戶的模擬器上顯示任何內容，而我能夠從服務器獲取數據

實際上，在項目中我想顯示庫中存在的所有用戶。我正在訪問服務器這是在Ubuntu上。顯示在控制檯（終端）上

以下消息： -

Started GET "/users.json" for 192.168.0.104 at 2013-05-05 22:05:01 -0700 
Processing by UsersController#index as JSON 
    User Load (0.4ms) SELECT "users".* FROM "users" WHERE (users.deleted = 0) ORDER BY users.id DESC 
    Admin Load (0.3ms) SELECT "admins".* FROM "admins" WHERE "admins"."id" = 1 AND (admins.deleted = 0) ORDER BY admins.id DESC LIMIT 1 
Completed 200 OK in 4ms (Views: 2.1ms | ActiveRecord: 0.6ms) 
[2013-05-05 22:05:01] WARN Could not determine content-length of response body. Set content-length of the response or set Response#chunked = true 

但是我不能夠顯示在屏幕機器人/仿真器的數據。

請幫我這個。

Answer 1

我錯過了你的setAdapterList()方法。

您的json pasers出現任何錯誤？你可以把你的活動從SecondActivity繼承嗎？

//modify getListView 
public ListView getListView() { 
    // TODO Auto-generated method stub 
    listView = (ListView)findViewById(r.your.listview); 
    return listView; 
} 

//modify setListAdapter 
private void setListAdapter(ListAdapter adapter) { 
    // TODO Auto-generated method stub 
    lv.setAdapter(adapter); 
}