Refactor retrofit service

app/src/main/AndroidManifest.xml

@@ -10,6 +10,7 @@
     <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
 
     <application
+        android:name=".CustomApplication"
         android:allowBackup="true"
         android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name"

app/src/main/java/com/testapp/AppUtils.java

@@ -4,7 +4,21 @@ import android.content.Context;
 import android.net.ConnectivityManager;
 import android.net.NetworkInfo;
 
+import com.google.gson.Gson;
+import com.google.gson.GsonBuilder;
+
+import java.io.File;
+import java.io.IOException;
+
+import okhttp3.Cache;
+import okhttp3.Interceptor;
+import okhttp3.OkHttpClient;
+import retrofit2.Retrofit;
+import retrofit2.converter.gson.GsonConverterFactory;
+
 public class AppUtils {
+    public static CanteeneoApiInterface service;
+    private static Context c;
 
     public static boolean isNetworkAvailable(Context c) {
         ConnectivityManager connectivity =(ConnectivityManager) c.getSystemService(Context.CONNECTIVITY_SERVICE);
@@ -23,4 +37,47 @@ public class AppUtils {
         }
         return false;
     }
+
+    public static void initREST(String serverIP, Context c) {
+        AppUtils.c = c;
+        File httpCacheDirectory = new File(c.getCacheDir(), "responses");
+        int cacheSize = 10 * 1024 * 1024; // 10MiB
+        Cache cache = new Cache(httpCacheDirectory, cacheSize);
+
+        OkHttpClient client = new OkHttpClient().newBuilder()
+                .addNetworkInterceptor(REWRITE_CACHE_CONTROL_INTERCEPTOR)
+                .cache(cache)
+                .build();
+
+        Gson gson = new GsonBuilder()
+                .setDateFormat("yyyy-MM-dd'T'HH:mm:ssZ")
+                .create();
+
+        Retrofit retrofit = new Retrofit.Builder()
+                .baseUrl("http://" + serverIP + ":5000/")
+                .client(client)
+                .addConverterFactory(GsonConverterFactory.create(gson))
+                .build();
+
+        service = retrofit.create(CanteeneoApiInterface.class);
+
+    }
+
+    private static final Interceptor REWRITE_CACHE_CONTROL_INTERCEPTOR = new Interceptor() {
+        @Override
+        public okhttp3.Response intercept(Chain chain) throws IOException {
+            okhttp3.Response origResponse = chain.proceed(chain.request());
+            if (AppUtils.isNetworkAvailable(c)) {
+                int maxAge = 60; // read from cache for 1 minute
+                return origResponse.newBuilder()
+                        .header("Cache-Control", "public, max-age=" + maxAge)
+                        .build();
+            } else {
+                int maxStale = 60 * 60 * 24 * 28; // tolerate 4-weeks stale
+                return origResponse.newBuilder()
+                        .header("Cache-Control", "public, only-if-cached, max-stale=" + maxStale)
+                        .build();
+            }
+        }
+    };
 }

app/src/main/java/com/testapp/CustomApplication.java

+package com.testapp;
+
+import android.app.Application;
+
+public class CustomApplication extends Application{
+    @Override
+    public void onCreate() {
+        super.onCreate();
+
+        AppUtils.initREST(getResources().getString(R.string.server_ip), getApplicationContext());
+    }
+}

app/src/main/java/com/testapp/NavDrawerActivity.java

@@ -56,28 +56,6 @@ public class NavDrawerActivity extends AppCompatActivity implements NavigationVi
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 
-        File httpCacheDirectory = new File(this.getCacheDir(), "responses");
-        int cacheSize = 10 * 1024 * 1024; // 10MiB
-        Cache cache = new Cache(httpCacheDirectory, cacheSize);
-
-        OkHttpClient client = new OkHttpClient().newBuilder()
-                .addNetworkInterceptor(REWRITE_CACHE_CONTROL_INTERCEPTOR)
-                .cache(cache)
-                .build();
-
-        Gson gson = new GsonBuilder()
-                .setDateFormat("yyyy-MM-dd'T'HH:mm:ssZ")
-                .create();
-
-        Retrofit retrofit = new Retrofit.Builder()
-                .baseUrl("http://" + getResources().getString(R.string.server_ip) + ":5000/")
-                .client(client)
-                .addConverterFactory(GsonConverterFactory.create(gson))
-                .build();
-
-        service = retrofit.create(CanteeneoApiInterface.class);
-        c = getApplicationContext();
-
         setContentView(R.layout.activity_nav_drawer);
         Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
         setSupportActionBar(toolbar);
@@ -253,23 +231,4 @@ public class NavDrawerActivity extends AppCompatActivity implements NavigationVi
             }
         });
     }
-
-
-    private static final Interceptor REWRITE_CACHE_CONTROL_INTERCEPTOR = new Interceptor() {
-        @Override
-        public okhttp3.Response intercept(Chain chain) throws IOException {
-            okhttp3.Response origResponse = chain.proceed(chain.request());
-            if (AppUtils.isNetworkAvailable(c)) {
-                int maxAge = 60; // read from cache for 1 minute
-                return origResponse.newBuilder()
-                        .header("Cache-Control", "public, max-age=" + maxAge)
-                        .build();
-            } else {
-                int maxStale = 60 * 60 * 24 * 28; // tolerate 4-weeks stale
-                return origResponse.newBuilder()
-                        .header("Cache-Control", "public, only-if-cached, max-stale=" + maxStale)
-                        .build();
-            }
-        }
-    };
 }