使用Volley調用多個服務

Question

我有一個MainActivity，其中創建了Swipeable選項卡，並從那裏調用兩個片段。我有2個Web服務的片段A和片段B，我必須解析來自服務器的數據。我正在使用凌空。當我在第一個片段時; Web服務都被調用，並且數據不是第一次加載。

但在第二次它顯示正確，但它應該是這樣的，當我在片段A中應該調用片段A的服務，並且當我在片段B中時，片段B的服務應該是調用。我附上了代碼片段。

MainActivity.java

public class MainActivity extends AppCompatActivity { 
    DrawerLayout mDrawerLayout; 
    NavigationView mNavigationView; 
    FragmentManager mFragmentManager; 
    FragmentTransaction mFragmentTransaction; 

    int status = 0 ; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 

     /** 
     *Setup the DrawerLayout and NavigationView 
     */ 

     mDrawerLayout = (DrawerLayout) findViewById(R.id.drawerLayout); 
     mNavigationView = (NavigationView) findViewById(R.id.shitstuff); 
     android.support.v7.widget.Toolbar toolbar = (android.support.v7.widget.Toolbar) findViewById(R.id.toolbar); 
     // Show menu icon 

     setSupportActionBar(toolbar); 
     getSupportActionBar().setDisplayShowHomeEnabled(true); 

     /** 
     * Lets inflate the very first fragment 
     * Here , we are inflating the NewsFragment as the first Fragment 
     */ 

     mFragmentManager = getSupportFragmentManager(); 
     mFragmentTransaction = mFragmentManager.beginTransaction(); 
     mFragmentTransaction.replace(R.id.containerView, new NewsFragment()).commit(); 

//  mNavigationView.setBackgroundColor(Color.parseColor("#CFCFCF")); 
     /** 
     * Setup click events on the Navigation View Items. 
     */ 

     mNavigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() { 
      @Override 
      public boolean onNavigationItemSelected(MenuItem menuItem) { 
       mDrawerLayout.closeDrawers(); 


       if (menuItem.getItemId() == R.id.nav_item_sent) { 
        FragmentTransaction fragmentTransaction = mFragmentManager.beginTransaction(); 
        fragmentTransaction.replace(R.id.containerView, new SportsFragment()).commit(); 

        status = 1; 

        if (status == 1){ 

        } 

       } 

       if (menuItem.getItemId() == R.id.nav_item_inbox) { 
        FragmentTransaction xfragmentTransaction = mFragmentManager.beginTransaction(); 
        xfragmentTransaction.replace(R.id.containerView, new NewsFragment()).commit(); 
       } 

       if (menuItem.getItemId() == R.id.nav_item_sent){ 
        FragmentTransaction xfragmentTransaction = mFragmentManager.beginTransaction(); 
        xfragmentTransaction.replace(R.id.containerView, new VideosFragment()).commit(); 
       } 

       if (menuItem.getItemId() == R.id.nav_item_draft) { 
        FragmentTransaction xfragmentTransaction = mFragmentManager.beginTransaction(); 
        xfragmentTransaction.replace(R.id.containerView, new OpinionFragment()).commit(); 
       } 

       if (menuItem.getItemId() == R.id.nav_item_sports) { 
        FragmentTransaction xfragmentTransaction = mFragmentManager.beginTransaction(); 
        xfragmentTransaction.replace(R.id.containerView, new SportsFragment()).commit(); 
       } 

       if (menuItem.getItemId() == R.id.nav_item_weather) { 
        FragmentTransaction xfragmentTransaction = mFragmentManager.beginTransaction(); 
        xfragmentTransaction.replace(R.id.containerView, new NewsFragment()).commit(); 
       } 

       return false; 
      } 

     }); 

     /** 
     * Setup Drawer Toggle of the Toolbar 
     */ 



    ActionBarDrawerToggle mDrawerToggle = new ActionBarDrawerToggle(this, mDrawerLayout, toolbar, R.string.app_name, 
      R.string.app_name); 

    mDrawerLayout.setDrawerListener(mDrawerToggle); 

    mDrawerToggle.syncState(); 

} 

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

     return true; 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     switch (item.getItemId()) { 
      case R.id.action_about_us: 
       Intent intent = new Intent(MainActivity.this, AboutUs.class); 
       startActivity(intent); 
       return true; 

      case R.id.action_terms_of_use: 
       Intent intent_two = new Intent(MainActivity.this, TermsUse.class); 
       startActivity(intent_two); 
       return true; 

      case R.id.action_privacy_policy: 
       Intent intent_three = new Intent(MainActivity.this, PrivacyPolicy.class); 
       startActivity(intent_three); 
       return true; 

      case R.id.action_contact_us: 
       Intent intent_four = new Intent(MainActivity.this, ContactUs.class); 
       startActivity(intent_four); 

      case R.id.search: 
//    hidetext(); 
       Toast.makeText(MainActivity.this, "In the development Phase... Thank You...", Toast.LENGTH_SHORT).show(); 
       return true; 
      default: 
       return super.onOptionsItemSelected(item); 
     } 
    } 

// private void hidetext() { 
// 
//  Intent i = new Intent(MainActivity.this, SearchResultActivity.class); 
//  startActivity(i); 
// } 
} 

TopNewsFragment

public class TopNewsFragment extends Fragment { 

    // Log tag 
    private static final String TAG = MainActivity.class.getSimpleName(); 

    private static final String url = "http://sikkimexpress.itstunner.com/api/homenewslist/topnews"; 
    private ProgressDialog pDialog; 
    private List<Movie> movieList = new ArrayList<Movie>(); 
    Movie movie; 
    private ListView listView; 
    private CustomListAdapter adapter; 
    String imageURL = "", title = "", description = ""; 
    public static final String KEY_ID = "news_id"; 
    public static final String KEY_HEADURL = "news_url"; 
    public static final String KEY_DETAILS = "news_details"; 
    public static final String KEY_TITLE = "news_title"; 

    RequestQueue requestQueue; 

    public TopNewsFragment() { 
     // Required empty public constructor 
    } 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 

    } 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     final View rootView = inflater.inflate(R.layout.fragment_news, container, false); 

     listView = (ListView) rootView.findViewById(R.id.list); 

     listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { 

      @Override 
      public void onItemClick(AdapterView<?> adapterView, View view, int Position, 
            long offset) { 
       // TODO Auto-generated method stub 
       Movie item = (Movie) adapter.getItem(Position); 
       Intent intent = new Intent(rootView.getContext(), DetailsPage.class); 
       intent.putExtra(KEY_ID, item.getNewsId()); 
       intent.putExtra(KEY_HEADURL, item.getThumbnailUrl()); 
       intent.putExtra(KEY_TITLE, item.getTitle()); 
       intent.putExtra(KEY_DETAILS, item.getDescription()); 

       startActivity(intent); 


      } 
     }); 

//  requestQueue = Volley.newRequestQueue(getActivity()); 
     adapter = new CustomListAdapter(getActivity(), movieList); 
     listView.setAdapter(adapter); 

     pDialog = new ProgressDialog(getActivity()); 
     pDialog.setMessage("Loading...Please Wait..."); 
     pDialog.setCancelable(false); 
     pDialog.show(); 

     Volley.newRequestQueue(getActivity()).add(new JsonObjectRequest(Request.Method.GET, url, new Response.Listener<JSONObject>() { 
      @Override 
      public void onResponse(JSONObject response) { 
       hidePDialog(); 
       try { 
        JSONArray jsonArray = response.getJSONArray("HomeNews"); 

//     if (jsonArray.length() == 0) { 
//      new AlertDialog.Builder(getActivity()) 
//        .setTitle("Alert") 
//        .setMessage("No Items found...") 
//        .setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() { 
//         public void onClick(DialogInterface dialog, int which) { 
//          // continue with delete 
//         } 
//        }) 
//        .setNegativeButton(android.R.string.no, new DialogInterface.OnClickListener() { 
//         public void onClick(DialogInterface dialog, int which) { 
//          // do nothing 
//         } 
//        }) 
//        .setIcon(android.R.drawable.ic_dialog_alert) 
//        .show(); 
//     } 

        for (int i = 0; i < jsonArray.length(); i++) { 
         JSONObject homenews = jsonArray.getJSONObject(i); 
         Movie movie = new Movie(); 
         movie.setNewsId(homenews.getString("NewsId")); 
         movie.setDateTime(homenews.getString("DateTime")); 
         movie.setNewsType(homenews.getString("NewsType")); 
         movie.setTitle(homenews.getString("Title")); 
         title = movie.setTitle(homenews.getString("Title")); 
         description = movie.setDescription(homenews.getString("Description")); 
         movie.setDescription(homenews.getString("Description")); 
         imageURL = movie.setThumbnailUrl(homenews.getString("MainImageThumbnail")); 
         movie.setThumbnailUrl(homenews.getString("MainImageThumbnail")); 

         movieList.add(movie); 

         System.out.println("Setting up in ListView"); 
//      System.out.println("Result:- " + newsId + " " + dateTime + " " + newsType + " " + title + " " + description + " " + mainImageURL); 
        } 
       } catch (JSONException e) { 
        e.printStackTrace(); 
       } 
       adapter.notifyDataSetChanged(); 
      } 
     }, new Response.ErrorListener() { 
      @Override 
      public void onErrorResponse(VolleyError error) { 
//    new AlertDialog.Builder(getActivity()) 
//      .setTitle("No Connectivity ") 
//      .setMessage("Please check your internet connectivity!") 
//      .setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() { 
//       public void onClick(DialogInterface dialog, int which) { 
//        // continue with delete 
//       } 
//      }) 
//        //.setNegativeButton(android.R.string.no, new DialogInterface.OnClickListener() { 
//        //public void onClick(DialogInterface dialog, int which) { 
//        // do nothing 
//        //} 
//        //}) 
//      .setIcon(android.R.drawable.ic_dialog_alert) 
//      .show(); 
       hidePDialog(); 
      } 
     })); 

//  AppController.getInstance().addToRequestQueue(jsonObjectRequest); 
//  requestQueue.add(jsonObjectRequest); 
     return rootView; 
    } 

    @Override 
    public void onAttach(Activity activity) { 
     super.onAttach(activity); 
    } 

    @Override 
    public void onDetach() { 
     super.onDetach(); 
    } 

    private void hidePDialog() { 
     if (pDialog != null) { 
      pDialog.dismiss(); 
      pDialog = null; 
     } 
    } 
} 

LatestNewsFragment.java

public class LatestNewsFragment extends Fragment { 

    // Log tag 
    private static final String TAG = MainActivity.class.getSimpleName(); 

    private static final String url = "http://sikkimexpress.itstunner.com/api/homenewslist/latest"; 
    private ProgressDialog pDialog; 
    private List<Movie> movieList = new ArrayList<Movie>(); 
    private ListView listView; 
    private CustomListAdapter adapter; 
    // contacts JSONArray 
    private JSONArray users = null; 
    RequestQueue requestQueue; 
    public static final String KEY_HEADURL="news_url"; 
    public static final String KEY_DETAILS="news_details"; 
    public static final String KEY_TITLE = "news_title"; 

    public LatestNewsFragment() { 
     // Required empty public constructor 
    } 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 

    } 

    @Override 
    public View onCreateView(LayoutInflater inflater, ViewGroup container, 
          Bundle savedInstanceState) { 
     final View rootView = inflater.inflate(R.layout.fragment_news, container, false); 

     listView = (ListView) rootView.findViewById(R.id.list); 

//  requestQueue = Volley.newRequestQueue(getActivity()); 
     adapter = new CustomListAdapter(getActivity(), movieList); 
     listView.setAdapter(adapter); 

     listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { 

      @Override 
      public void onItemClick(AdapterView<?> adapterView, View view, int Position, 
            long offset) { 
       // TODO Auto-generated method stub 
       Movie item = (Movie) adapter.getItem(Position); 
       Intent intent = new Intent(rootView.getContext(), DetailsPage.class); 
//    intent.putExtra("URL", movie.getThumbnailUrl()); 
//    intent.putExtra("title", movie.getTitle()); 
//    intent.putExtra("description", movie.getDescription()); 

       intent.putExtra(KEY_HEADURL, item.getThumbnailUrl()); 
       intent.putExtra(KEY_TITLE, item.getTitle()); 
       intent.putExtra(KEY_DETAILS, item.getDescription()); 

       startActivity(intent); 


      } 
     }); 

     pDialog = new ProgressDialog(getActivity()); 
     // Showing progress dialog before making http request 
     pDialog.setMessage("Loading...Please Wait..."); 
     pDialog.setCancelable(false); 
     pDialog.show(); 

     Volley.newRequestQueue(getActivity()).add(new JsonObjectRequest(Request.Method.GET, url, new Response.Listener<JSONObject>() { 
//   JsonObjectRequest jsonObjectRequest = 

      @Override 
      public void onResponse(JSONObject response) { 
       try { 
        hidePDialog(); 

        JSONArray jsonArray = response.getJSONArray("HomeNews"); 

//     if (jsonArray.length() == 0){ 
//      new AlertDialog.Builder(getActivity()) 
//        .setTitle("Alert") 
//        .setMessage("No Items found...") 
//        .setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() { 
//         public void onClick(DialogInterface dialog, int which) { 
//          // continue with delete 
//         } 
//        }) 
//        .setNegativeButton(android.R.string.no, new DialogInterface.OnClickListener() { 
//         public void onClick(DialogInterface dialog, int which) { 
//          // do nothing 
//         } 
//        }) 
//        .setIcon(android.R.drawable.ic_dialog_alert) 
//        .show(); 
//     } 

        for (int i = 0; i < jsonArray.length(); i++) { 
         JSONObject homenews = jsonArray.getJSONObject(i); 
         Movie movie = new Movie(); 
         movie.setNewsId(homenews.getString("NewsId")); 
         movie.setDateTime(homenews.getString("DateTime")); 
         movie.setNewsType(homenews.getString("NewsType")); 
         movie.setTitle(homenews.getString("Title")); 
         movie.setDescription(homenews.getString("Description")); 
         movie.setThumbnailUrl(homenews.getString("MainImageThumbnail")); 

         movieList.add(movie); 
         System.out.println("Setting up in ListView"); 
        } 
       } catch (JSONException e) { 
        e.printStackTrace(); 
       } 
       adapter.notifyDataSetChanged(); 
      } 
     }, 

       new Response.ErrorListener() { 
        @Override 
        public void onErrorResponse(VolleyError error) { 
//      new AlertDialog.Builder(getActivity()) 
//        .setTitle("No Connectivity ") 
//        .setMessage("Please check your internet connectivity!") 
//        .setPositiveButton(android.R.string.yes, new DialogInterface.OnClickListener() { 
//         public void onClick(DialogInterface dialog, int which) { 
//          // continue with delete 
//         } 
//        }) 
//          //.setNegativeButton(android.R.string.no, new DialogInterface.OnClickListener() { 
//          //public void onClick(DialogInterface dialog, int which) { 
//          // do nothing 
//          //} 
//          //}) 
//        .setIcon(android.R.drawable.ic_dialog_alert) 
//        .show(); 
         hidePDialog(); 
        } 
       })); 

//  AppController.getInstance().addToRequestQueue(jsonObjectRequest); 
//  requestQueue.add(jsonObjectRequest); 
     return rootView; 
    } 

    @Override 
    public void onAttach(Activity activity) { 
     super.onAttach(activity); 
    } 

    @Override 
    public void onDetach() { 
     super.onDetach(); 
    } 

    private void hidePDialog() { 
     if (pDialog != null) { 
      pDialog.dismiss(); 
      pDialog = null; 
     } 
    } 
} 

Answer 1

可能發生的情況是，即使您一次只查看一個片段，也會加載這兩個片段。而不是每個請求創建一個新的RequestQueue，你應該只有一個。例如創建一個應用程序類，像這樣：

public class MyApp extends Application { 

    private RequestQueue mRequestQueue; 

    private static MyApp mInstance; 

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

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

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

     return mRequestQueue; 
    } 

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

不要忘了你的應用程序類添加到您的清單中的<activity>標籤中：

<application 
    android:name=".MyApp" 

現在你可以把請求從該隊列您片段：

JsonObjectRequest req = new JsonObjectRequest(Request.Method.GET, 
      URL, null, new Response.Listener<JSONObject>() { 

     @Override 
     public void onResponse(JSONObject response) { 
      //Do something with response 
     } 
    }, new Response.ErrorListener() { 

     @Override 
     public void onErrorResponse(VolleyError error) { 
      //Do something with error 
     } 
    }); 

    //Put the actual request on the queue 
    MyApp.getInstance().addToRequestQueue(req);