如何解析json分支值

Question

我是android編程的新手。我試圖通過解析它來在我的android應用程序中烘烤用戶id的值，但錯誤表示沒有用戶值。如何從android中的json數據獲取輸入？我附上我的logcat錯誤below.Can任何人請幫助我？在先進的感謝

"status": "SUCCESS", 
"msg": "Login Successful", 
"data": { 
    "user": { 
     "id": "6", 
     "first_name": "e", 
     "last_name": "ff", 
     "address": "dr", 
     "mobile": "55", 
     "email": "rokes1990@live.com", 
     "password": "4124bc0a9335c27f086f24ba207a4912", 
     "pwd_reset_key": "", 
     "name_on_card": "", 
     "card_number": "", 
     "expiry_date": "", 
     "cvv": "", 
     "tdatetime": "2014-07-11 02:55:08" 
    } 
} 

logcat的錯誤：

09-05 03:36:00.567: D/dalvikvm(2227): GC_FOR_ALLOC freed 379K, 8% free 5765K/6220K, paused 76ms, total 82ms 
09-05 03:36:02.077: W/Response(2227): {"GET":[],"POST":{"action":"login","app_secret":"jkhljkUILJGJkljhkjUGLG87796587687HGKJhghkjKUYGKJHjhgjUYGKUY7865876hgKUYGK","email":"rokes1990@live.com","password":"aa"},"status":"SUCCESS","msg":"Login Successful","data":{"user":{"id":"6","first_name":"e","last_name":"ff","address":"dr","mobile":"55","email":"rokes1990@live.com","password":"4124bc0a9335c27f086f24ba207a4912","pwd_reset_key":"","name_on_card":"","card_number":"","expiry_date":"","cvv":"","tdatetime":"2014-07-11 02:55:08"}}} 
09-05 03:36:02.107: W/System.err(2227): org.json.JSONException: No value for user 
09-05 03:36:02.117: W/System.err(2227):  at org.json.JSONObject.get(JSONObject.java:355) 
09-05 03:36:02.117: W/System.err(2227):  at org.json.JSONObject.getString(JSONObject.java:515) 
09-05 03:36:02.147: W/System.err(2227):  at example.atlcitylimo.Main.postLoginData(Main.java:116) 
09-05 03:36:02.147: W/System.err(2227):  at example.atlcitylimo.Main.onClick(Main.java:181) 
09-05 03:36:02.147: W/System.err(2227):  at android.view.View.performClick(View.java:4438) 
09-05 03:36:02.147: W/System.err(2227):  at android.view.View$PerformClick.run(View.java:18422) 
09-05 03:36:02.147: W/System.err(2227):  at android.os.Handler.handleCallback(Handler.java:733) 
09-05 03:36:02.147: W/System.err(2227):  at android.os.Handler.dispatchMessage(Handler.java:95) 
09-05 03:36:02.147: W/System.err(2227):  at android.os.Looper.loop(Looper.java:136) 
09-05 03:36:02.157: W/System.err(2227):  at android.app.ActivityThread.main(ActivityThread.java:5017) 
09-05 03:36:02.157: W/System.err(2227):  at java.lang.reflect.Method.invokeNative(Native Method) 
09-05 03:36:02.157: W/System.err(2227):  at java.lang.reflect.Method.invoke(Method.java:515) 
09-05 03:36:02.157: W/System.err(2227):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 
09-05 03:36:02.157: W/System.err(2227):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 
09-05 03:36:02.157: W/System.err(2227):  at dalvik.system.NativeStart.main(Native Method) 

Answer 1

protected String getId(String result) { 
    try { 
    JSONObject jsonObject = new JSONObject(result); 
    JSONObject data = new JSONObject(jsonObject.getString("data")); 
    JSONObject user = new JSONObject(jsonObject.getString("user")); 
    String id = user.getString("id"); 
    return id; 
    }catch (Exception e) { 
    Log.d("error", e.getLocalizedMessage()); 
    } 
    return null; 

} 

Answer 2

您可以使用排解析JSON字符串。在下面的鏈接檢查「使JSON請求」：

http://www.androidhive.info/2014/05/android-working-with-volley-library-1/

凌空提供了一個易於使JSON請求。如果您在響應中期待json對象，則應該使用JsonObjectRequest類或者如果響應是json數組，則應使用JsonArrayRequest類。 StringRequest類將用於獲取任何類型的字符串數據。響應可以是json，xml，html或純文本。

您可以JsonObjectRequest開始得到的JSONObject：

JsonObjectRequest jsonObjReq = new JsonObjectRequest(Method.GET, url, null, 
       new Response.Listener<JSONObject>() { 

        @Override 
        public void onResponse(JSONObject response) { 
         //response is the JSONObject that you get from the request 
         //you can play with that request to get the exact info you want 
         String status = response.getString("status"); 
         String msg = response.getString("msg"); 
         JSONObject data = null; 
         try{ 
          data = response.getJSONObject("data"); 
         }catch (JSONException e1) { 
          e1.printStackTrace(); 
         } 

         JSONObject user = null; 
         try{ 
          user = data.getJSONObject("user"); 
         }catch (JSONException e1) { 
          e1.printStackTrace(); 
         } 

         String id = user.getString("id"); 
         String first_name = user.getString("first_name"); 
         //and goes on for the rest of the user info 
        } 
       }, new Response.ErrorListener() { 

        @Override 
        public void onErrorResponse(VolleyError error) { 
         VolleyLog.d(TAG, "Error: " + error.getMessage()); 
        } 
       }); 

，你也需要對這一請求添加到請求隊列

// Adding request to request queue 
AppController.getInstance().addToRequestQueue(req, tag_json_arry); 

和你的AppController類如下：

import android.app.Application; 
import android.text.TextUtils; 

import com.android.volley.Request; 
import com.android.volley.RequestQueue; 
import com.android.volley.toolbox.ImageLoader; 
import com.android.volley.toolbox.Volley; 

public class AppController extends Application { 

    public static final String TAG = AppController.class 
      .getSimpleName(); 

    private RequestQueue mRequestQueue; 
    private ImageLoader mImageLoader; 

    private static AppController mInstance; 

    @Override 
    public void onCreate() { 
     super.onCreate(); 
     mInstance = this; 
    } 

    public static synchronized AppController getInstance() { 
     return mInstance; 
    } 

    public RequestQueue getRequestQueue() { 
     if (mRequestQueue == null) { 
      mRequestQueue = Volley.newRequestQueue(getApplicationContext()); 
     } 

     return mRequestQueue; 
    } 

    public ImageLoader getImageLoader() { 
     getRequestQueue(); 
     if (mImageLoader == null) { 
      mImageLoader = new ImageLoader(this.mRequestQueue, 
        new LruBitmapCache()); 
     } 
     return this.mImageLoader; 
    } 

    public <T> void addToRequestQueue(Request<T> req, String tag) { 
     // set the default tag if tag is empty 
     req.setTag(TextUtils.isEmpty(tag) ? TAG : tag); 
     getRequestQueue().add(req); 
    } 

    public <T> void addToRequestQueue(Request<T> req) { 
     req.setTag(TAG); 
     getRequestQueue().add(req); 
    } 

    public void cancelPendingRequests(Object tag) { 
     if (mRequestQueue != null) { 
      mRequestQueue.cancelAll(tag); 
     } 
    } 
} 

最後添加到您的Manifest.xml中，以下是<application>個標籤

<application 
     android:name="info.androidhive.volleyexamples.app.AppController"