调试，测试并调整修改了代码及结构

src/com/chinasofti/dao/ActivityDAO.java

@@ -1,12 +0,0 @@
-package com.chinasofti.dao;
-
-import com.chinasofti.model.Activity;
-import java.util.List;
-
-public interface ActivityDAO {
-    List<Activity> selectAll();
-    Activity selectById(Long id);
-    int insert(Activity activity);
-    int update(Activity activity);
-    int deleteById(Long id);
-}