修复monkey测试出现的两个bug

Aria/src/main/java/com/arialyy/aria/core/queue/DownloadTaskQueue.java

@@ -106,6 +106,10 @@ public class DownloadTaskQueue implements ITaskQueue {
   }
 
   @Override public void reTryStart(Task task) {
+    if (task == null){
+      Log.w(TAG, "重试下载失败，task 为null");
+      return;
+    }
     if (!task.isDownloading()) {
       task.start();
     } else {

Aria/src/main/java/com/arialyy/aria/core/task/DownloadUtil.java

@@ -75,7 +75,7 @@ final class DownloadUtil implements IDownloadUtil {
     mDownloadEntity = entity;
     mListener = downloadListener;
     THREAD_NUM = threadNum;
-    mFixedThreadPool = Executors.newFixedThreadPool(THREAD_NUM);
+    mFixedThreadPool = Executors.newFixedThreadPool(Integer.MAX_VALUE);
   }
 
   public IDownloadListener getListener() {
@@ -292,7 +292,7 @@ final class DownloadUtil implements IDownloadUtil {
             for (int l : recordL) {
               if (l == -1) continue;
               Runnable task = mTask.get(l);
-              if (task != null) {
+              if (task != null && !mFixedThreadPool.isShutdown()) {
                 mFixedThreadPool.execute(task);
               }
             }

README.md

@@ -113,4 +113,4 @@ License
     distributed under the License is distributed on an "AS IS" BASIS,
     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     See the License for the specific language governing permissions and
-    limitations under the License.
+    limitations under the License.