添加获取扩展字段的方法

Aria/src/main/java/com/arialyy/aria/core/inf/AbsTarget.java

@@ -48,6 +48,14 @@ public abstract class AbsTarget<ENTITY extends AbsEntity, TASK_ENTITY extends Ab
     return this;
   }
 
+  /**
+   * 获取存放的扩展字段
+   * 设置扩展字段{@link #setExtendField(String)}
+   */
+  public String getExtendField() {
+    return entity.getStr();
+  }
+
   /**
    * 获取任务状态
    *
@@ -87,11 +95,7 @@ public abstract class AbsTarget<ENTITY extends AbsEntity, TASK_ENTITY extends Ab
    * 删除记录
    */
   public void removeRecord() {
-    if (entity instanceof DownloadEntity) {
-      ((DownloadEntity) entity).deleteData();
-    } else if (entity instanceof UploadEntity) {
-      ((UploadEntity) entity).deleteData();
-    }
+    entity.deleteData();
   }
 
   /**