diff --git a/Aria/src/main/java/com/arialyy/aria/core/AriaManager.java b/Aria/src/main/java/com/arialyy/aria/core/AriaManager.java
index 5d587e9d..6dbfb75b 100644
--- a/Aria/src/main/java/com/arialyy/aria/core/AriaManager.java
+++ b/Aria/src/main/java/com/arialyy/aria/core/AriaManager.java
@@ -33,6 +33,7 @@ import com.arialyy.aria.core.download.DownloadReceiver;
 import com.arialyy.aria.core.inf.ICmd;
 import com.arialyy.aria.core.inf.IReceiver;
 import com.arialyy.aria.core.queue.DownloadTaskQueue;
+import com.arialyy.aria.core.queue.UploadTaskQueue;
 import com.arialyy.aria.core.upload.UploadReceiver;
 import com.arialyy.aria.orm.DbEntity;
 import com.arialyy.aria.orm.DbUtil;
@@ -56,7 +57,6 @@ import java.util.Map;
   private static final Object LOCK = new Object();
   @SuppressLint("StaticFieldLeak") private static volatile AriaManager INSTANCE = null;
   private Map<String, IReceiver> mReceivers = new HashMap<>();
-  private DownloadTaskQueue mDTaskQueue;
 
   public static Context APP;
   private List<ICmd> mCommands = new ArrayList<>();
@@ -84,13 +84,6 @@ import java.util.Map;
     return DbEntity.findAllData(DownloadEntity.class);
   }
 
-  /**
-   * 获取任务队列
-   */
-  public DownloadTaskQueue getTaskQueue() {
-    return mDTaskQueue;
-  }
-
   /**
    * 设置命令
    */
@@ -190,7 +183,7 @@ import java.util.Map;
       Log.w(TAG, "最大任务数不能小于 1");
       return this;
     }
-    mDTaskQueue.setDownloadNum(maxDownloadNum);
+    DownloadTaskQueue.getInstance().setDownloadNum(maxDownloadNum);
     return this;
   }
 
diff --git a/Aria/src/main/java/com/arialyy/aria/core/command/IDownloadCmd.java b/Aria/src/main/java/com/arialyy/aria/core/command/AbsCmd.java
similarity index 69%
rename from Aria/src/main/java/com/arialyy/aria/core/command/IDownloadCmd.java
rename to Aria/src/main/java/com/arialyy/aria/core/command/AbsCmd.java
index 00afc7e2..72a86147 100644
--- a/Aria/src/main/java/com/arialyy/aria/core/command/IDownloadCmd.java
+++ b/Aria/src/main/java/com/arialyy/aria/core/command/AbsCmd.java
@@ -16,10 +16,13 @@
 
 package com.arialyy.aria.core.command;
 
-import com.arialyy.aria.core.AriaManager;
+import com.arialyy.aria.core.download.DownloadTaskEntity;
 import com.arialyy.aria.core.inf.ITaskEntity;
+import com.arialyy.aria.core.queue.DownloadTaskQueue;
 import com.arialyy.aria.core.queue.ITaskQueue;
 import com.arialyy.aria.core.inf.ICmd;
+import com.arialyy.aria.core.queue.UploadTaskQueue;
+import com.arialyy.aria.core.upload.UploadTaskEntity;
 import com.arialyy.aria.util.CheckUtil;
 import com.arialyy.aria.util.CommonUtil;
 
@@ -27,7 +30,7 @@ import com.arialyy.aria.util.CommonUtil;
  * Created by lyy on 2016/8/22.
  * 下载命令
  */
-public abstract class IDownloadCmd<T extends ITaskEntity> implements ICmd {
+public abstract class AbsCmd<T extends ITaskEntity> implements ICmd {
   ITaskQueue mQueue;
   T mEntity;
   String TAG;
@@ -36,11 +39,15 @@ public abstract class IDownloadCmd<T extends ITaskEntity> implements ICmd {
   /**
    * @param targetName 产生任务的对象名
    */
-  IDownloadCmd(String targetName, T entity) {
+  AbsCmd(String targetName, T entity) {
     CheckUtil.checkTaskEntity(entity);
     mTargetName = targetName;
     mEntity = entity;
     TAG = CommonUtil.getClassName(this);
-    mQueue = AriaManager.getInstance(AriaManager.APP).getTaskQueue();
+    if (entity instanceof DownloadTaskEntity) {
+      mQueue = DownloadTaskQueue.getInstance();
+    } else if (entity instanceof UploadTaskEntity) {
+      mQueue = UploadTaskQueue.getInstance();
+    }
   }
 }
\ No newline at end of file
diff --git a/Aria/src/main/java/com/arialyy/aria/core/command/AddCmd.java b/Aria/src/main/java/com/arialyy/aria/core/command/AddCmd.java
index f113fb8a..7643e2b2 100644
--- a/Aria/src/main/java/com/arialyy/aria/core/command/AddCmd.java
+++ b/Aria/src/main/java/com/arialyy/aria/core/command/AddCmd.java
@@ -16,25 +16,27 @@
 
 package com.arialyy.aria.core.command;
 
+import android.util.Log;
+import com.arialyy.aria.core.inf.ITask;
 import com.arialyy.aria.core.inf.ITaskEntity;
 
 /**
  * Created by lyy on 2016/8/22.
  * 添加任务的命令
  */
-class AddCmd<T extends ITaskEntity> extends IDownloadCmd<T> {
+class AddCmd<T extends ITaskEntity> extends AbsCmd<T> {
 
   AddCmd(String targetName, T entity) {
     super(targetName, entity);
   }
 
   @Override public void executeCmd() {
-    //  DownloadTask task = mQueue.getTask(mEntity.downloadEntity);
-    //  if (task == null) {
-    //    mQueue.createTask(mTargetName, mEntity);
-    //  } else {
-    //    Log.w(TAG, "添加命令执行失败，【该任务已经存在】");
-    //  }
+    ITask task = mQueue.getTask(mEntity.getEntity());
+    if (task == null){
+      mQueue.createTask(mTargetName, mEntity);
+    }else {
+      Log.w(TAG, "添加命令执行失败，【该任务已经存在】");
+    }
   }
 
   //AddCmd(DownloadTaskEntity entity) {
diff --git a/Aria/src/main/java/com/arialyy/aria/core/command/CancelCmd.java b/Aria/src/main/java/com/arialyy/aria/core/command/CancelCmd.java
index 35d80a59..7024143a 100644
--- a/Aria/src/main/java/com/arialyy/aria/core/command/CancelCmd.java
+++ b/Aria/src/main/java/com/arialyy/aria/core/command/CancelCmd.java
@@ -16,19 +16,29 @@
 
 package com.arialyy.aria.core.command;
 
+import com.arialyy.aria.core.inf.ITask;
 import com.arialyy.aria.core.inf.ITaskEntity;
 
 /**
  * Created by lyy on 2016/9/20.
  * 取消命令
  */
-class CancelCmd<T extends ITaskEntity> extends IDownloadCmd<T> {
+class CancelCmd<T extends ITaskEntity> extends AbsCmd<T> {
   CancelCmd(String targetName, T entity) {
     super(targetName, entity);
   }
 
   @Override public void executeCmd() {
-
+    ITask task = mQueue.getTask(mEntity.getEntity());
+    if (task == null) {
+      task = mQueue.createTask(mTargetName, mEntity);
+    }
+    if (task != null) {
+      if (mTargetName != null) {
+        task.setTargetName(mTargetName);
+      }
+      mQueue.cancelTask(task);
+    }
   }
 
   //CancelCmd(DownloadTaskEntity entity) {
diff --git a/Aria/src/main/java/com/arialyy/aria/core/command/CmdFactory.java b/Aria/src/main/java/com/arialyy/aria/core/command/CmdFactory.java
index 4c2a2526..a9e7efc9 100644
--- a/Aria/src/main/java/com/arialyy/aria/core/command/CmdFactory.java
+++ b/Aria/src/main/java/com/arialyy/aria/core/command/CmdFactory.java
@@ -67,7 +67,7 @@ public class CmdFactory {
    * @param type 命令类型{@link #TASK_CREATE}、{@link #TASK_START}、{@link #TASK_CANCEL}、{@link
    * #TASK_STOP}
    */
-  public <T extends ITaskEntity> IDownloadCmd createCmd(String target, T entity, int type) {
+  public <T extends ITaskEntity> AbsCmd createCmd(String target, T entity, int type) {
     switch (type) {
       case TASK_CREATE:
         return createAddCmd(target, entity);
diff --git a/Aria/src/main/java/com/arialyy/aria/core/command/StartCmd.java b/Aria/src/main/java/com/arialyy/aria/core/command/StartCmd.java
index 7ec000b0..9c2f6124 100644
--- a/Aria/src/main/java/com/arialyy/aria/core/command/StartCmd.java
+++ b/Aria/src/main/java/com/arialyy/aria/core/command/StartCmd.java
@@ -16,20 +16,28 @@
 
 package com.arialyy.aria.core.command;
 
+import com.arialyy.aria.core.inf.ITask;
 import com.arialyy.aria.core.inf.ITaskEntity;
 
 /**
  * Created by lyy on 2016/8/22.
  * 开始命令
  */
-class StartCmd<T extends ITaskEntity> extends IDownloadCmd<T> {
+class StartCmd<T extends ITaskEntity> extends AbsCmd<T> {
 
   StartCmd(String targetName, T entity) {
     super(targetName, entity);
   }
 
   @Override public void executeCmd() {
-
+    ITask task = mQueue.getTask(mEntity.getEntity());
+    if (task == null) {
+      task = mQueue.createTask(mTargetName, mEntity);
+    }
+    if (task != null) {
+      task.setTargetName(mTargetName);
+      mQueue.startTask(task);
+    }
   }
 
   //StartCmd(DownloadTaskEntity entity) {
diff --git a/Aria/src/main/java/com/arialyy/aria/core/command/StopCmd.java b/Aria/src/main/java/com/arialyy/aria/core/command/StopCmd.java
index 8dbfbc6a..3d617b32 100644
--- a/Aria/src/main/java/com/arialyy/aria/core/command/StopCmd.java
+++ b/Aria/src/main/java/com/arialyy/aria/core/command/StopCmd.java
@@ -16,20 +16,37 @@
 
 package com.arialyy.aria.core.command;
 
+import android.text.TextUtils;
+import android.util.Log;
+import com.arialyy.aria.core.inf.IEntity;
+import com.arialyy.aria.core.inf.ITask;
 import com.arialyy.aria.core.inf.ITaskEntity;
 
 /**
  * Created by lyy on 2016/9/20.
  * 停止命令
  */
-class StopCmd<T extends ITaskEntity> extends IDownloadCmd<T> {
+class StopCmd<T extends ITaskEntity> extends AbsCmd<T> {
 
   StopCmd(String targetName, T entity) {
     super(targetName, entity);
   }
 
   @Override public void executeCmd() {
-
+    ITask task = mQueue.getTask(mEntity.getEntity());
+    if (task == null) {
+      if (mEntity.getEntity().getState() == IEntity.STATE_RUNNING) {
+        task = mQueue.createTask(mTargetName, mEntity);
+        mQueue.stopTask(task);
+      } else {
+        Log.w(TAG, "停止命令执行失败，【调度器中没有该任务】");
+      }
+    } else {
+      if (!TextUtils.isEmpty(mTargetName)) {
+        task.setTargetName(mTargetName);
+      }
+      mQueue.stopTask(task);
+    }
   }
 
   //StopCmd(DownloadTaskEntity entity) {
diff --git a/Aria/src/main/java/com/arialyy/aria/core/download/DownloadEntity.java b/Aria/src/main/java/com/arialyy/aria/core/download/DownloadEntity.java
index 3f368118..479d2652 100644
--- a/Aria/src/main/java/com/arialyy/aria/core/download/DownloadEntity.java
+++ b/Aria/src/main/java/com/arialyy/aria/core/download/DownloadEntity.java
@@ -129,6 +129,7 @@ public class DownloadEntity extends DbEntity implements Parcelable, IEntity{
     this.fileSize = fileSize;
   }
 
+  @Override
   public int getState() {
     return state;
   }
diff --git a/Aria/src/main/java/com/arialyy/aria/core/download/DownloadReceiver.java b/Aria/src/main/java/com/arialyy/aria/core/download/DownloadReceiver.java
index d6a42681..0bf74b62 100644
--- a/Aria/src/main/java/com/arialyy/aria/core/download/DownloadReceiver.java
+++ b/Aria/src/main/java/com/arialyy/aria/core/download/DownloadReceiver.java
@@ -19,7 +19,7 @@ import android.support.annotation.NonNull;
 import com.arialyy.aria.core.AriaManager;
 import com.arialyy.aria.core.inf.IReceiver;
 import com.arialyy.aria.core.command.CmdFactory;
-import com.arialyy.aria.core.command.IDownloadCmd;
+import com.arialyy.aria.core.command.AbsCmd;
 import com.arialyy.aria.core.scheduler.DownloadSchedulers;
 import com.arialyy.aria.core.scheduler.OnSchedulerListener;
 import com.arialyy.aria.util.CheckUtil;
@@ -109,7 +109,7 @@ public class DownloadReceiver implements IReceiver {
   public void stopAllTask() {
     final AriaManager ariaManager = AriaManager.getInstance(AriaManager.APP);
     List<DownloadEntity> allEntity = ariaManager.getAllDownloadEntity();
-    List<IDownloadCmd> stopCmds = new ArrayList<>();
+    List<AbsCmd> stopCmds = new ArrayList<>();
     for (DownloadEntity entity : allEntity) {
       if (entity.getState() == DownloadEntity.STATE_RUNNING) {
         stopCmds.add(CommonUtil.createDownloadCmd(targetName, new DownloadTaskEntity(entity),
@@ -125,7 +125,7 @@ public class DownloadReceiver implements IReceiver {
   public void cancelAllTask() {
     final AriaManager ariaManager = AriaManager.getInstance(AriaManager.APP);
     List<DownloadEntity> allEntity = ariaManager.getAllDownloadEntity();
-    List<IDownloadCmd> cancelCmds = new ArrayList<>();
+    List<AbsCmd> cancelCmds = new ArrayList<>();
     for (DownloadEntity entity : allEntity) {
       cancelCmds.add(CommonUtil.createDownloadCmd(targetName, new DownloadTaskEntity(entity),
           CmdFactory.TASK_CANCEL));
diff --git a/Aria/src/main/java/com/arialyy/aria/core/download/DownloadTarget.java b/Aria/src/main/java/com/arialyy/aria/core/download/DownloadTarget.java
index 59e19b38..25f19e10 100644
--- a/Aria/src/main/java/com/arialyy/aria/core/download/DownloadTarget.java
+++ b/Aria/src/main/java/com/arialyy/aria/core/download/DownloadTarget.java
@@ -20,7 +20,7 @@ import android.text.TextUtils;
 import com.arialyy.aria.core.AriaManager;
 import com.arialyy.aria.core.RequestEnum;
 import com.arialyy.aria.core.command.CmdFactory;
-import com.arialyy.aria.core.command.IDownloadCmd;
+import com.arialyy.aria.core.command.AbsCmd;
 import com.arialyy.aria.util.CheckUtil;
 import com.arialyy.aria.util.CommonUtil;
 import java.util.ArrayList;
@@ -141,7 +141,7 @@ public class DownloadTarget {
    * 开始下载
    */
   public void start() {
-    List<IDownloadCmd> cmds = new ArrayList<>();
+    List<AbsCmd> cmds = new ArrayList<>();
     cmds.add(CommonUtil.createDownloadCmd(targetName, taskEntity, CmdFactory.TASK_CREATE));
     cmds.add(CommonUtil.createDownloadCmd(targetName, taskEntity, CmdFactory.TASK_START));
     AriaManager.getInstance(AriaManager.APP).setCmds(cmds).exe();
@@ -179,7 +179,7 @@ public class DownloadTarget {
    * 是否在下载
    */
   public boolean isDownloading() {
-    return AriaManager.getInstance(AriaManager.APP).getTaskQueue().getTask(entity).isDownloading();
+    return AriaManager.getInstance(AriaManager.APP).getDownloadTaskQueue().getTask(entity).isDownloading();
   }
 
   /**
diff --git a/Aria/src/main/java/com/arialyy/aria/core/download/DownloadTask.java b/Aria/src/main/java/com/arialyy/aria/core/download/DownloadTask.java
index 1dcc0454..83fc3d46 100644
--- a/Aria/src/main/java/com/arialyy/aria/core/download/DownloadTask.java
+++ b/Aria/src/main/java/com/arialyy/aria/core/download/DownloadTask.java
@@ -133,6 +133,7 @@ public class DownloadTask implements ITask {
     return mTargetName;
   }
 
+  @Override
   public void setTargetName(String targetName) {
     this.mTargetName = targetName;
   }
diff --git a/Aria/src/main/java/com/arialyy/aria/core/download/DownloadTaskEntity.java b/Aria/src/main/java/com/arialyy/aria/core/download/DownloadTaskEntity.java
index 91d15f7b..c5a61b92 100644
--- a/Aria/src/main/java/com/arialyy/aria/core/download/DownloadTaskEntity.java
+++ b/Aria/src/main/java/com/arialyy/aria/core/download/DownloadTaskEntity.java
@@ -16,6 +16,7 @@
 package com.arialyy.aria.core.download;
 
 import com.arialyy.aria.core.RequestEnum;
+import com.arialyy.aria.core.inf.IEntity;
 import com.arialyy.aria.core.inf.ITaskEntity;
 import java.util.HashMap;
 import java.util.Map;
@@ -33,4 +34,8 @@ public class DownloadTaskEntity implements ITaskEntity {
   public DownloadTaskEntity(DownloadEntity downloadEntity) {
     this.downloadEntity = downloadEntity;
   }
+
+  @Override public IEntity getEntity() {
+    return downloadEntity;
+  }
 }
diff --git a/Aria/src/main/java/com/arialyy/aria/core/inf/IEntity.java b/Aria/src/main/java/com/arialyy/aria/core/inf/IEntity.java
index 4d4bcbb9..59d3ee4b 100644
--- a/Aria/src/main/java/com/arialyy/aria/core/inf/IEntity.java
+++ b/Aria/src/main/java/com/arialyy/aria/core/inf/IEntity.java
@@ -1,3 +1,18 @@
+/*
+ * Copyright (C) 2016 AriaLyy(https://github.com/AriaLyy/Aria)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * 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.
+ */
 package com.arialyy.aria.core.inf;
 
 import com.arialyy.aria.orm.Ignore;
@@ -44,4 +59,6 @@ public interface IEntity {
    */
   @Ignore public static final int STATE_CANCEL       = 7;
 
+  public int getState();
+
 }
diff --git a/Aria/src/main/java/com/arialyy/aria/core/inf/ITask.java b/Aria/src/main/java/com/arialyy/aria/core/inf/ITask.java
index aa8436cf..bcf7b025 100644
--- a/Aria/src/main/java/com/arialyy/aria/core/inf/ITask.java
+++ b/Aria/src/main/java/com/arialyy/aria/core/inf/ITask.java
@@ -33,4 +33,6 @@ public interface ITask {
   public long getFileSize();
 
   public long getCurrentProgress();
+
+  public void setTargetName(String targetName);
 }
diff --git a/Aria/src/main/java/com/arialyy/aria/core/inf/ITaskEntity.java b/Aria/src/main/java/com/arialyy/aria/core/inf/ITaskEntity.java
index af026170..0780b0bc 100644
--- a/Aria/src/main/java/com/arialyy/aria/core/inf/ITaskEntity.java
+++ b/Aria/src/main/java/com/arialyy/aria/core/inf/ITaskEntity.java
@@ -1,3 +1,18 @@
+/*
+ * Copyright (C) 2016 AriaLyy(https://github.com/AriaLyy/Aria)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * 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.
+ */
 package com.arialyy.aria.core.inf;
 
 /**
@@ -6,4 +21,6 @@ package com.arialyy.aria.core.inf;
 
 public interface ITaskEntity {
 
+  public IEntity getEntity();
+
 }
diff --git a/Aria/src/main/java/com/arialyy/aria/core/upload/UploadEntity.java b/Aria/src/main/java/com/arialyy/aria/core/upload/UploadEntity.java
index 5992a657..051b16d4 100644
--- a/Aria/src/main/java/com/arialyy/aria/core/upload/UploadEntity.java
+++ b/Aria/src/main/java/com/arialyy/aria/core/upload/UploadEntity.java
@@ -61,7 +61,7 @@ public class UploadEntity extends DbEntity implements IEntity, Parcelable {
     this.failNum = failNum;
   }
 
-  public int getState() {
+  @Override public int getState() {
     return state;
   }
 
@@ -114,8 +114,7 @@ public class UploadEntity extends DbEntity implements IEntity, Parcelable {
     this.failNum = in.readInt();
   }
 
-  @Ignore
-  public static final Creator<UploadEntity> CREATOR = new Creator<UploadEntity>() {
+  @Ignore public static final Creator<UploadEntity> CREATOR = new Creator<UploadEntity>() {
     @Override public UploadEntity createFromParcel(Parcel source) {
       return new UploadEntity(source);
     }
diff --git a/Aria/src/main/java/com/arialyy/aria/core/upload/UploadTask.java b/Aria/src/main/java/com/arialyy/aria/core/upload/UploadTask.java
index 6ed54b3c..5b79b1ed 100644
--- a/Aria/src/main/java/com/arialyy/aria/core/upload/UploadTask.java
+++ b/Aria/src/main/java/com/arialyy/aria/core/upload/UploadTask.java
@@ -36,7 +36,7 @@ public class UploadTask implements ITask {
     mUtil = new UploadUtil(mTaskEntity, mListener);
   }
 
-  void setTargetName(String targetName) {
+  @Override public void setTargetName(String targetName) {
     mTargetName = targetName;
   }
 
diff --git a/Aria/src/main/java/com/arialyy/aria/core/upload/UploadTaskEntity.java b/Aria/src/main/java/com/arialyy/aria/core/upload/UploadTaskEntity.java
index c4853d83..030789ea 100644
--- a/Aria/src/main/java/com/arialyy/aria/core/upload/UploadTaskEntity.java
+++ b/Aria/src/main/java/com/arialyy/aria/core/upload/UploadTaskEntity.java
@@ -1,6 +1,7 @@
 package com.arialyy.aria.core.upload;
 
 import com.arialyy.aria.core.RequestEnum;
+import com.arialyy.aria.core.inf.IEntity;
 import com.arialyy.aria.core.inf.ITaskEntity;
 import java.util.HashMap;
 import java.util.Map;
@@ -28,4 +29,8 @@ public class UploadTaskEntity implements ITaskEntity {
   public UploadTaskEntity(UploadEntity downloadEntity) {
     this.uploadEntity = downloadEntity;
   }
+
+  @Override public IEntity getEntity() {
+    return uploadEntity;
+  }
 }
diff --git a/Aria/src/main/java/com/arialyy/aria/util/CommonUtil.java b/Aria/src/main/java/com/arialyy/aria/util/CommonUtil.java
index 2da387e1..c15260e5 100644
--- a/Aria/src/main/java/com/arialyy/aria/util/CommonUtil.java
+++ b/Aria/src/main/java/com/arialyy/aria/util/CommonUtil.java
@@ -21,9 +21,8 @@ import android.content.Intent;
 import android.content.SharedPreferences;
 import android.net.Uri;
 import android.util.Log;
-import com.arialyy.aria.core.download.DownloadTaskEntity;
 import com.arialyy.aria.core.command.CmdFactory;
-import com.arialyy.aria.core.command.IDownloadCmd;
+import com.arialyy.aria.core.command.AbsCmd;
 import com.arialyy.aria.core.inf.ITaskEntity;
 import java.io.File;
 import java.io.FileInputStream;
@@ -41,7 +40,7 @@ import java.util.Properties;
 public class CommonUtil {
   private static final String TAG = "util";
 
-  public static <T extends ITaskEntity> IDownloadCmd createDownloadCmd(String target, T entity, int cmd) {
+  public static <T extends ITaskEntity> AbsCmd createDownloadCmd(String target, T entity, int cmd) {
     return CmdFactory.getInstance().createCmd(target, entity, cmd);
   }