Cache.Entryがjsonデータを取得しない

Question

json配列がキャッシュに格納されていないことを除いて、私はvollyを使用してデータとその作業を完全に取得しています。

は、ここに私のコードです：私はすでにマニフェストでAppcontroller宣言している

private void getCacheValue() { 
    Cache cache = AppController.getInstance().getRequestQueue().getCache(); 
    Cache.Entry entry = cache.get(Endpoints.product_url); 


    if(entry != null){ 
     Log.w("Logdata:", ""+ entry.toString()); 
     try { 
      String data = new String(entry.data, "UTF-8"); 
      JSONArray jsonArray = new JSONArray(data); 

      // handle data, like converting it to xml, json, bitmap etc., 
      Log.v("Hello", data); 
      listProduct.clear(); 
      for (int i = 0; i < jsonArray.length(); i++) { 
       try { 
        JSONObject object = jsonArray.getJSONObject(i); 
        ItemCategories image = new ItemCategories(); 
        image.setCategoryItem(object.getString(key_title)); 
        image.setUrlThumb(object.getString(key_image)); 

        listProduct.add(image); 
        } catch (JSONException e) { 
         Log.e(TAG, "Json parsing error: " + e.getMessage()); 
        } 
       } 

       adapterProductList.notifyDataSetChanged(); 
       progressBarMain.setVisibility(View.GONE); 
       internetError.setVisibility(View.GONE); 
       recycleProductList.setVisibility(View.VISIBLE); 

      } catch (UnsupportedEncodingException e) { 
       e.printStackTrace(); 
      } catch (JSONException e) { 
       e.printStackTrace(); 
       Log.v("JSON EXCEPTION", "DECLINE"); 
      } 
    } else { 
     if(isNetworkAvailable()) { 
      fetchImages(); 
     } else { 
      progressBarMain.setVisibility(View.GONE); 
      internetError.setVisibility(View.VISIBLE); 
     } 
    } 
} 

private void fetchImages() { 
    JsonObjectRequest jsObjRequest = 
     new JsonObjectRequest(Request.Method.GET, Endpoints.product_url(String) null, 
      new Response.Listener<JSONObject>() {  
       @Override 
       public void onResponse(JSONObject response) { 
        listProduct.clear(); 
        try { 
         JSONArray routes = response.getJSONArray(key_product); 
         for (int i = 0; i < routes.length(); i++) { 
          JSONObject object = routes.getJSONObject(i); 
          ItemCategories categories = new ItemCategories(); 
          categories.setCategoryItem(object.getString(key_title)); 
          categories.setUrlThumb(object.getString(key_image)); 

          listProduct.add(categories); 
         } 
         adapterProductList.notifyDataSetChanged(); 
         progressBarMain.setVisibility(View.GONE); 
         internetError.setVisibility(View.GONE); 
         recycleProductList.setVisibility(View.VISIBLE); 
         } catch (JSONException e) { 
          e.printStackTrace(); 
          Toast.makeText(getApplicationContext(), 
              "Error: " + e.getMessage(), 
              Toast.LENGTH_LONG).show(); 
         } 
        } 
        }, 
        new Response.ErrorListener() { 
         @Override 
         public void onErrorResponse(VolleyError error) { 
          VolleyLog.d(TAG, "Error: " + error.getMessage()); 
         } 
        }); 
    // Adding request to request queue 
    AppController.getInstance().addToRequestQueue(jsObjRequest); 
} 

が、キャッシングが動作していない理由を私は知りません。ここで

は私のjson_data

fetchImage()あるrecyclerviewにデータがあるので、働いています。ただし、データをオフラインで取得しようとすると、キャッシュにデータを保存できないため、データが表示されます。

Answer 1

デフォルトでは、応答ヘッダーが許可されている場合、データのみがキャッシュされます。

public static Cache.Entry parseCacheHeaders(NetworkResponse response) { 
    long now = System.currentTimeMillis(); 

    Map<String, String> headers = response.headers; 

    long serverDate = 0; 
    long lastModified = 0; 
    long serverExpires = 0; 
    long softExpire = 0; 
    long finalExpire = 0; 
    long maxAge = 0; 
    long staleWhileRevalidate = 0; 
    boolean hasCacheControl = false; 
    boolean mustRevalidate = false; 

    String serverEtag = null; 
    String headerValue; 

    headerValue = headers.get("Date"); 
    if (headerValue != null) { 
     serverDate = parseDateAsEpoch(headerValue); 
    } 

    headerValue = headers.get("Cache-Control"); 
    if (headerValue != null) { 
     hasCacheControl = true; 
     String[] tokens = headerValue.split(","); 
     for (int i = 0; i < tokens.length; i++) { 
      String token = tokens[i].trim(); 
      if (token.equals("no-cache") || token.equals("no-store")) { 
       return null; 
      } else if (token.startsWith("max-age=")) { 
       try { 
        maxAge = Long.parseLong(token.substring(8)); 
       } catch (Exception e) { 
       } 
      } else if (token.startsWith("stale-while-revalidate=")) { 
       try { 
        staleWhileRevalidate = Long.parseLong(token.substring(23)); 
       } catch (Exception e) { 
       } 
      } else if (token.equals("must-revalidate") || token.equals("proxy-revalidate")) { 
       mustRevalidate = true; 
      } 
     } 
    } 

    headerValue = headers.get("Expires"); 
    if (headerValue != null) { 
     serverExpires = parseDateAsEpoch(headerValue); 
    } 

    headerValue = headers.get("Last-Modified"); 
    if (headerValue != null) { 
     lastModified = parseDateAsEpoch(headerValue); 
    } 

    serverEtag = headers.get("ETag"); 

    // Cache-Control takes precedence over an Expires header, even if both exist and Expires 
    // is more restrictive. 
    if (hasCacheControl) { 
     softExpire = now + maxAge * 1000; 
     finalExpire = mustRevalidate 
       ? softExpire 
       : softExpire + staleWhileRevalidate * 1000; 
    } else if (serverDate > 0 && serverExpires >= serverDate) { 
     // Default semantic for Expire header in HTTP specification is softExpire. 
     softExpire = now + (serverExpires - serverDate); 
     finalExpire = softExpire; 
    } 

    Cache.Entry entry = new Cache.Entry(); 
    entry.data = response.data; 
    entry.etag = serverEtag; 
    entry.softTtl = softExpire; 
    entry.ttl = finalExpire; 
    entry.serverDate = serverDate; 
    entry.lastModified = lastModified; 
    entry.responseHeaders = headers; 

    return entry; 
} 

あなたが変更することができます。
1のCache-Control
2.
3. MAXAGE

詳細については機能の下を参照してください。有効期限： ボレーは、以下のレスポンスヘッダに基づいて応答をキャッシュ要求オブジェクトをオーバーライドすることによってデフォルトのキャッシュポリシー。 あなたが好きJsonObjectRequestを上書きすることができますようごfetchImage機能を更新

public class CustomJsonObjectRequest extends JsonObjectRequest { 
    public CustomJsonObjectRequest(int method, String url, JSONObject jsonRequest, Response.Listener<JSONObject> listener, Response.ErrorListener errorListener) { 
     super(method, url, jsonRequest, listener, errorListener); 
    } 

    public CustomJsonObjectRequest(String url, JSONObject jsonRequest, Response.Listener<JSONObject> listener, Response.ErrorListener errorListener) { 
     super(url, jsonRequest, listener, errorListener); 
    } 

    @Override 
    protected Response<JSONObject> parseNetworkResponse(NetworkResponse response) { 
     try { 
      String jsonString = new String(response.data, 
        HttpHeaderParser.parseCharset(response.headers, PROTOCOL_CHARSET)); 
      return Response.success(new JSONObject(jsonString), 
        parseIgnoreCacheHeaders(response)); 
     } catch (UnsupportedEncodingException e) { 
      return Response.error(new ParseError(e)); 
     } catch (JSONException je) { 
      return Response.error(new ParseError(je)); 
     } 
    } 

    public static Cache.Entry parseIgnoreCacheHeaders(NetworkResponse response) { 
     long now = System.currentTimeMillis(); 
     Map<String, String> headers = response.headers; 
     long serverDate = 0; 
     String serverEtag = null; 
     String headerValue; 

     headerValue = headers.get("Date"); 
     if (headerValue != null) { 
      serverDate = HttpHeaderParser.parseDateAsEpoch(headerValue); 
     } 

     serverEtag = headers.get("ETag"); 

     final long cacheHitButRefreshed = 3 * 60 * 1000; // in 3 minutes cache will be hit, but also refreshed on background 
     final long cacheExpired = 24 * 60 * 60 * 1000; // in 24 hours this cache entry expires completely 
     final long softExpire = now + cacheHitButRefreshed; 
     final long ttl = now + cacheExpired; 

     Cache.Entry entry = new Cache.Entry(); 
     entry.data = response.data; 
     entry.etag = serverEtag; 
     entry.softTtl = softExpire; 
     entry.ttl = ttl; 
     entry.serverDate = serverDate; 
     entry.responseHeaders = headers; 

     return entry; 
    } 
} 

：参考

private void fetchImages() { 

    CustomJsonObjectRequest jsObjRequest = new CustomJsonObjectRequest() 
      (Request.Method.GET, Endpoints.product_url, (String) null, new Response.Listener<JSONObject>() { 

       @Override 
       public void onResponse(JSONObject response) { 
        listProduct.clear(); 
        try { 
         JSONArray routes = response.getJSONArray(key_product); 
         for (int i = 0; i < routes.length(); i++) { 
          JSONObject object = routes.getJSONObject(i); 
          ItemCategories categories = new ItemCategories(); 

          categories.setCategoryItem(object.getString(key_title)); 
          categories.setUrlThumb(object.getString(key_image)); 

          listProduct.add(categories); 
         } 
         adapterProductList.notifyDataSetChanged(); 
         progressBarMain.setVisibility(View.GONE); 
         internetError.setVisibility(View.GONE); 
         recycleProductList.setVisibility(View.VISIBLE); 
        } catch (JSONException e) { 
         e.printStackTrace(); 
         Toast.makeText(getApplicationContext(), 
           "Error: " + e.getMessage(), 
           Toast.LENGTH_LONG).show(); 
        } 
       } 
      }, new Response.ErrorListener() { 
       @Override 
       public void onErrorResponse(VolleyError error) { 
        VolleyLog.d(TAG, "Error: " + error.getMessage()); 

       } 
      }); 
    // Adding request to request queue 
    AppController.getInstance().addToRequestQueue(jsObjRequest); 
} 

、キャッシュにあなたにも、ストアデータを行うAndroid Volley + JSONObjectRequest Caching