fix bug #6, #9, #11

android/build.gradle

@@ -34,5 +34,5 @@ android {
 }
 
 dependencies {
-    api "android.arch.work:work-runtime:1.0.0-alpha06"
+    api "android.arch.work:work-runtime:1.0.0-alpha07"
 }

android/src/main/java/vn/hunghd/flutterdownloader/DownloadWorker.java

@@ -63,7 +63,7 @@ public class DownloadWorker extends Worker {
     @Override
     public Result doWork() {
         Context context = getApplicationContext();
-        dbHelper = new TaskDbHelper(context);
+        dbHelper = TaskDbHelper.getInstance(context);
 
         String url = getInputData().getString(ARG_URL);
         String fileName = getInputData().getString(ARG_FILE_NAME);

android/src/main/java/vn/hunghd/flutterdownloader/FlutterDownloaderPlugin.java

@@ -13,16 +13,21 @@
 import android.os.Bundle;
 import android.provider.BaseColumns;
 import android.support.v4.content.LocalBroadcastManager;
+import android.util.Log;
 
 
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.UUID;
+import java.util.concurrent.Executors;
+import java.util.concurrent.LinkedBlockingDeque;
+import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 
 import androidx.work.BackoffPolicy;
+import androidx.work.Configuration;
 import androidx.work.Constraints;
 import androidx.work.Data;
 import androidx.work.NetworkType;
@@ -34,7 +39,6 @@
 import io.flutter.plugin.common.MethodChannel;
 import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
 import io.flutter.plugin.common.PluginRegistry;
-import io.flutter.view.FlutterNativeView;
 
 public class FlutterDownloaderPlugin implements MethodCallHandler {
     private static final String CHANNEL = "vn.hunghd/downloader";
@@ -43,6 +47,8 @@ public class FlutterDownloaderPlugin implements MethodCallHandler {
     private MethodChannel flutterChannel;
     private TaskDbHelper dbHelper;
 
+    public static int maximumConcurrentTask;
+
     private final BroadcastReceiver updateProcessEventReceiver = new BroadcastReceiver() {
         @Override
         public void onReceive(Context context, Intent intent) {
@@ -56,7 +62,11 @@ public void onReceive(Context context, Intent intent) {
     private FlutterDownloaderPlugin(Context context, BinaryMessenger messenger) {
         flutterChannel = new MethodChannel(messenger, CHANNEL);
         flutterChannel.setMethodCallHandler(this);
-        dbHelper = new TaskDbHelper(context);
+        dbHelper = TaskDbHelper.getInstance(context);
+        Log.d(TAG, "maximumConcurrentTask = " + maximumConcurrentTask);
+        WorkManager.initialize(context, new Configuration.Builder()
+                .setExecutor(Executors.newFixedThreadPool(Math.max(maximumConcurrentTask, 1)))
+                .build());
     }
 
     @SuppressLint("NewApi")

android/src/main/java/vn/hunghd/flutterdownloader/TaskDbHelper.java

@@ -10,6 +10,8 @@ public class TaskDbHelper extends SQLiteOpenHelper {
     public static final int DATABASE_VERSION = 1;
     public static final String DATABASE_NAME = "download_tasks.db";
 
+    private static TaskDbHelper instance = null;
+
     private static final String SQL_CREATE_ENTRIES =
             "CREATE TABLE " + TaskEntry.TABLE_NAME + " (" +
             TaskEntry._ID + " INTEGER PRIMARY KEY," +
@@ -23,7 +25,20 @@ public class TaskDbHelper extends SQLiteOpenHelper {
     private static final String SQL_DELETE_ENTRIES =
             "DROP TABLE IF EXISTS " + TaskEntry.TABLE_NAME;
 
-    public TaskDbHelper(Context context) {
+
+    public static TaskDbHelper getInstance(Context ctx) {
+
+        // Use the application context, which will ensure that you
+        // don't accidentally leak an Activity's context.
+        // See this article for more information: http://bit.ly/6LRzfx
+        if (instance == null) {
+            instance = new TaskDbHelper(ctx.getApplicationContext());
+        }
+        return instance;
+    }
+
+
+    private TaskDbHelper(Context context) {
         super(context, DATABASE_NAME, null, DATABASE_VERSION);
     }
 

example/android/app/src/main/java/vn/hunghd/flutterdownloaderexample/MainActivity.java

@@ -3,11 +3,13 @@
 import android.os.Bundle;
 import io.flutter.app.FlutterActivity;
 import io.flutter.plugins.GeneratedPluginRegistrant;
+import vn.hunghd.flutterdownloader.FlutterDownloaderPlugin;
 
 public class MainActivity extends FlutterActivity {
   @Override
   protected void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
+    FlutterDownloaderPlugin.maximumConcurrentTask = 2;
     GeneratedPluginRegistrant.registerWith(this);
   }
 }

example/ios/Runner/AppDelegate.m

@@ -1,10 +1,13 @@
 #include "AppDelegate.h"
 #include "GeneratedPluginRegistrant.h"
+#include "FlutterDownloaderPlugin.h"
 
 @implementation AppDelegate
 
 - (BOOL)application:(UIApplication *)application
     didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
+
+  [FlutterDownloaderPlugin setMaximumConcurrentTask: 2];
   [GeneratedPluginRegistrant registerWithRegistry:self];
   // Override point for customization after application launch.
   return [super application:application didFinishLaunchingWithOptions:launchOptions];

ios/Classes/FlutterDownloaderPlugin.h

@@ -1,4 +1,9 @@
 #import <Flutter/Flutter.h>
 
 @interface FlutterDownloaderPlugin : NSObject<FlutterPlugin>
-@end
+
++ (int) maximumConcurrentTask;
+
++ (void) setMaximumConcurrentTask:(int)val;
+
+@end

ios/Classes/FlutterDownloaderPlugin.m

@@ -30,6 +30,20 @@ @interface FlutterDownloaderPlugin()<NSURLSessionTaskDelegate, NSURLSessionDownl
 
 @implementation FlutterDownloaderPlugin
 
+static int maximumConcurrentTask;
+
++ (int)maximumConcurrentTask {
+    @synchronized(self) {
+        return maximumConcurrentTask;
+    }
+}
+
++ (void)setMaximumConcurrentTask:(int)val {
+    @synchronized(self) {
+        maximumConcurrentTask = val;
+    }
+}
+
 + (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar>*)registrar {
 
     FlutterDownloaderPlugin* instance = [[FlutterDownloaderPlugin alloc] initWithBinaryMessenger:registrar.messenger];
@@ -93,9 +107,9 @@ - (instancetype)initWithBinaryMessenger: (NSObject<FlutterBinaryMessenger>*) mes
         _flutterChannel = [FlutterMethodChannel
                                 methodChannelWithName:@"vn.hunghd/downloader"
                                 binaryMessenger:messenger];
-
+        NSLog(@"maximumConcurrentTask: %d", FlutterDownloaderPlugin.maximumConcurrentTask);
         NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:[NSString stringWithFormat:@"%@.download.background", NSBundle.mainBundle.bundleIdentifier]];
-        sessionConfiguration.HTTPMaximumConnectionsPerHost = 5;
+        sessionConfiguration.HTTPMaximumConnectionsPerHost = MAX(FlutterDownloaderPlugin.maximumConcurrentTask, 1);
         _session = [NSURLSession sessionWithConfiguration:sessionConfiguration delegate:self delegateQueue:nil];
 
         _downloadInfo = [NSMutableDictionary new];