Improve some aspects of the Downloader implementation

app/src/debug/java/org/schabi/newpipe/DebugApp.java

@@ -15,6 +15,8 @@ import com.squareup.leakcanary.LeakCanary;
 import com.squareup.leakcanary.LeakDirectoryProvider;
 import com.squareup.leakcanary.RefWatcher;
 
+import org.schabi.newpipe.extractor.Downloader;
+
 import java.io.File;
 import java.util.concurrent.TimeUnit;
 
@@ -33,7 +35,12 @@ public class DebugApp extends App {
     public void onCreate() {
         super.onCreate();
         initStetho();
-        Downloader.client = new OkHttpClient.Builder().addNetworkInterceptor(new StethoInterceptor()).readTimeout(30, TimeUnit.SECONDS).build();
+    }
+
+    @Override
+    protected Downloader getDownloader() {
+        return org.schabi.newpipe.Downloader.init(new OkHttpClient.Builder()
+                .addNetworkInterceptor(new StethoInterceptor()));
     }
 
     private void initStetho() {

app/src/main/java/org/schabi/newpipe/App.java

@@ -19,6 +19,7 @@ import org.acra.config.ACRAConfiguration;
 import org.acra.config.ACRAConfigurationException;
 import org.acra.config.ConfigurationBuilder;
 import org.acra.sender.ReportSenderFactory;
+import org.schabi.newpipe.extractor.Downloader;
 import org.schabi.newpipe.extractor.NewPipe;
 import org.schabi.newpipe.report.AcraReportSenderFactory;
 import org.schabi.newpipe.report.ErrorActivity;
@@ -83,7 +84,7 @@ public class App extends Application {
         // Initialize settings first because others inits can use its values
         SettingsActivity.initSettings(this);
 
-        NewPipe.init(Downloader.getInstance());
+        NewPipe.init(getDownloader());
         NewPipeDatabase.init(this);
         StateSaver.init(this);
         initNotificationChannel();
@@ -94,6 +95,10 @@ public class App extends Application {
         configureRxJavaErrorHandler();
     }
 
+    protected Downloader getDownloader() {
+        return org.schabi.newpipe.Downloader.init(null);
+    }
+
     private void configureRxJavaErrorHandler() {
         // https://github.com/ReactiveX/RxJava/wiki/What's-different-in-2.0#error-handling
         RxJavaPlugins.setErrorHandler(new Consumer<Throwable>() {

app/src/main/java/org/schabi/newpipe/Downloader.java

@@ -1,8 +1,12 @@
 package org.schabi.newpipe;
 
+import android.support.annotation.Nullable;
+import android.text.TextUtils;
+
 import org.schabi.newpipe.extractor.exceptions.ReCaptchaException;
 
 import java.io.IOException;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.TimeUnit;
@@ -10,6 +14,7 @@ import java.util.concurrent.TimeUnit;
 import okhttp3.OkHttpClient;
 import okhttp3.Request;
 import okhttp3.Response;
+import okhttp3.ResponseBody;
 
 
 /*
@@ -33,34 +38,38 @@ import okhttp3.Response;
  */
 
 public class Downloader implements org.schabi.newpipe.extractor.Downloader {
-
     public static final String USER_AGENT = "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:43.0) Gecko/20100101 Firefox/43.0";
-    private static String mCookies = "";
 
-    private static Downloader instance = null;
+    private static Downloader instance;
+    private String mCookies;
+    private OkHttpClient client;
 
-    protected static OkHttpClient client = new OkHttpClient.Builder().readTimeout(30, TimeUnit.SECONDS).build();
+    private Downloader(OkHttpClient.Builder builder) {
+        this.client = builder
+                .readTimeout(30, TimeUnit.SECONDS)
+                //.cache(new Cache(new File(context.getExternalCacheDir(), "okhttp"), 16 * 1024 * 1024))
+                .build();
+    }
 
-    private Downloader() {
+    /**
+     * It's recommended to call exactly once in the entire lifetime of the application.
+     *
+     * @param builder if null, default builder will be used
+     */
+    public static Downloader init(@Nullable OkHttpClient.Builder builder) {
+        return instance = new Downloader(builder != null ? builder : new OkHttpClient.Builder());
     }
 
     public static Downloader getInstance() {
-        if (instance == null) {
-            synchronized (Downloader.class) {
-                if (instance == null) {
-                    instance = new Downloader();
-                }
-            }
-        }
         return instance;
     }
 
-    public static synchronized void setCookies(String cookies) {
-        Downloader.mCookies = cookies;
+    public String getCookies() {
+        return mCookies;
     }
 
-    public static synchronized String getCookies() {
-        return Downloader.mCookies;
+    public void setCookies(String cookies) {
+        mCookies = cookies;
     }
 
     /**
@@ -89,22 +98,32 @@ public class Downloader implements org.schabi.newpipe.extractor.Downloader {
      */
     @Override
     public String download(String siteUrl, Map<String, String> customProperties) throws IOException, ReCaptchaException {
-        Request.Builder requestBuilder = new Request.Builder().url(siteUrl).addHeader("User-Agent", USER_AGENT).method("GET", null);
-        for (Map.Entry<String, String> header : customProperties.entrySet()) {
-            requestBuilder = requestBuilder.addHeader(header.getKey(), header.getValue());
-        }
-        if (getCookies().length() > 0) {
-            requestBuilder = requestBuilder.addHeader("Cookie", getCookies());
-        }
-        Request request = requestBuilder.build();
+        final Request.Builder requestBuilder = new Request.Builder()
+                .method("GET", null).url(siteUrl)
+                .addHeader("User-Agent", USER_AGENT);
 
-        Response response = client.newCall(request).execute();
+        for (Map.Entry<String, String> header : customProperties.entrySet()) {
+            requestBuilder.addHeader(header.getKey(), header.getValue());
+        }
+
+        if (!TextUtils.isEmpty(mCookies)) {
+            requestBuilder.addHeader("Cookie", mCookies);
+        }
+
+        final Request request = requestBuilder.build();
+        final Response response = client.newCall(request).execute();
+        final ResponseBody body = response.body();
 
         if (response.code() == 429) {
             throw new ReCaptchaException("reCaptcha Challenge requested");
         }
 
-        return response.body().string();
+        if (body == null) {
+            response.close();
+            return null;
+        }
+
+        return body.string();
     }
 
     /**
@@ -116,6 +135,6 @@ public class Downloader implements org.schabi.newpipe.extractor.Downloader {
      */
     @Override
     public String download(String siteUrl) throws IOException, ReCaptchaException {
-        return download(siteUrl, new HashMap<>());
+        return download(siteUrl, Collections.emptyMap());
     }
 }

app/src/main/java/org/schabi/newpipe/ReCaptchaActivity.java

@@ -107,7 +107,7 @@ public class ReCaptchaActivity extends AppCompatActivity {
             // find cookies : s_gl & goojf and Add cookies to Downloader
             if (find_access_cookies(cookies)) {
                 // Give cookies to Downloader class
-                Downloader.setCookies(mCookies);
+                Downloader.getInstance().setCookies(mCookies);
 
                 // Closing activity and return to parent
                 setResult(RESULT_OK);