j2EE，框架采用struts2,spring,hibernate,服务器端处理请求的顺序是action > service > dao .
因为所有对象的service都有增删改查操作,所以我们使用一个基类,然后所有的service类都继承这个基类,这个service基类的代码如下:

public class BaseServiceImpl<T, E>  {
    
    //the class of the bean's dao .
    public T  dao ;

    //save object
    public boolean set( E obj ) {
        if ( dao==null ) return false;    //@1
        if ( obj==null ) return true;
        
        try {
            Class clazz = dao.getClass();
            Method method = clazz.getMethod( "save" , obj.getClass() );    //@2
            //clazz.getDeclaredMethod(name, parameterTypes)
            boolean R = (Boolean)  method.invoke( dao , (Object) obj );
            return R;
        } catch (Exception e) {
            e.printStackTrace();
            return false;
        } 
    }

}

下面给出service类的代码,他继承自 BaseServiceImpl :

@Component("abnormalListManage")
public class FreightCenter_abnormalListManageImpl <E> extends BaseServiceImpl<FreightCenter_abnormalListDao,FreightCenter_abnormalList> implements FreightCenter_abnormalListManage,reflectData  {
    @Resource(name="abnormalListDao") 
    private FreightCenter_abnormalListDao listDao;
        
    public FreightCenter_abnormalListManageImpl() {
        super.dao = listDao;
    }
    
}

**同样的dao类也有基类,然后每个dao类都继承自这个基类
dao基类的代码如下:**

public class BaseDaoImpl<T, E> {
    
    //SessionFactory for create session 
    public SessionFactory sessionFactory = null;    
    //the class of the bean's manage
    public T manage = null;
    
    public boolean save( E obj ) {
        //do sth.
    }
    
}

dao类代码如下:

@Transactional
@Component("abnormalListDao")
public class FreightCenter_abnormalListDaoImpl extends BaseDaoImpl<FreightCenter_abnormalListManage, FreightCenter_abnormalList> implements FreightCenter_abnormalListDao{
    @Resource
    private SessionFactory sessionFactory;
    
    @Resource( name="abnormalListManage" )
    private FreightCenter_abnormalListManage abnormalListManage;
    
    public FreightCenter_abnormalListDaoImpl() {
        super.sessionFactory = sessionFactory;
        super.manage = abnormalListManage;
    }
}

现在问题来了,当我们执行service类的set方法时，set方法里面的语句:
if ( dao==null ) return false; //在 service 基类 BaseServiceImpl 里面,标注为@1
在这个语句中，成员变量 dao 是 null 值,个人分析如下:
service类 FreightCenter_abnormalListManageImpl 是由spring来管理,他是在服务器运行时初始化的
初始化这个类时运行了构造方法,构造方法中将ListDao传递给基类的变量 dao ，但是这个时候 ,listDao肯定是null,因为spring肯定是在类初始化完成后才给ListDao赋值!
为了解决这个问题，我们在service类里面重写了set方法
修改后,service类的实现类代码如下:

@Component("abnormalListManage")
public class FreightCenter_abnormalListManageImpl <E> extends BaseServiceImpl<FreightCenter_abnormalListDao,FreightCenter_abnormalList> implements FreightCenter_abnormalListManage,reflectData  {
    @Resource(name="abnormalListDao") 
    private FreightCenter_abnormalListDao listDao;
    
    public FreightCenter_abnormalListManageImpl() {
        super.dao = listDao;
    }
    public boolean set( FreightCenter_abnormalList obj ) {    //重写set方法
        super.dao = listDao;
        return super.set( obj );
    }
}

这样就解决了上面的问题 .

但是,另外的问题出现了，当执行到语句( 使用@2来标注 ):

• Method method = clazz.getMethod( "save" , obj.getClass() );
  boolean R = (Boolean) method.invoke( dao , (Object) obj );*
  时报错,save方法不存在!

我现在的问题是:
1 在service类里面,如果我不重写set方法,如何将变量listDao的值传递给service基类?我希望是在service类初始化之后传递,如何解决?如果可以,我就不用重写那么多方法了,因为我还有好多方法需要重写.
2 为什么反射调用dao类的save方法时会报错?难道继承自基类(父类)的方法不属于本类的方法?