之前有看過(guò)一些ssh2中采用dao---service---action分層結(jié)構(gòu)寫(xiě)的程序，一開(kāi)始并不明白為什么這樣寫(xiě)，慢慢自己用dao/service/action模式寫(xiě)一些程序后，才對(duì)這分層結(jié)構(gòu)有一定理解。
個(gè)人理解：1、dao層主要是包括一些對(duì)數(shù)據(jù)庫(kù)操作的接口和實(shí)現(xiàn)例如：CRUD。
                    例如：public void save(User user ) throws Exception;//接口
                                public void save(User user ) throws Exception{ //實(shí)現(xiàn)，繼承HibernateDaoSupport
                                                   getHibernateTemplate().save(user);                                           
                                                                 }
        
                    2、service層只要是實(shí)現(xiàn)一些業(yè)務(wù)邏輯，業(yè)務(wù)邏輯實(shí)現(xiàn)也是使用dao層提供的對(duì)數(shù)據(jù)庫(kù)操作的接口和實(shí)現(xiàn)。        
                    例如：public int loginValid(String user,String pass)throws Exception;//驗(yàn)證用戶(hù)登錄合法接口
                                public int loginValid(String user,String pass)throws Exception{
                                                      ....................dao層里面的方法

                                                              }

                    3、action層實(shí)現(xiàn)調(diào)用業(yè)務(wù)邏輯方法來(lái)處理用戶(hù)的請(qǐng)求。
                                public String  execute() throws Exception
                                {
                                    ...............................................
                                }