使用Aspect注释将Inter-Type声明从.aj转换为.java

时间:2016-04-21 21:41:31

标签: java aop aspectj aspectj-maven-plugin

我有这种情况。 这是我的Village.java

public class Village{

    private Integer vid;
    private String villageName;
    private String district;

    public Integer getVid() {
        return vid;
    }
    public void setVid(Integer vid) {
        this.vid = vid;
    }
    public String getVillageName() {
        return villageName;
    }
    public void setVillageName(String villageName) {
        this.villageName = villageName;
    }
    public String getDistrict() {
        return district;
    }
    public void setDistrict(String district) {
        this.district = district;
    }
}

这是我的Dao.java界面:

public interface Dao<T> {
    public void insert();
    public void update();
    public void delete();
}

这是我的方面Village_Dao.aj(你可以忽略静态方法逻辑):

import org.apache.ibatis.session.SqlSession;
import com.madx.finance.data.utils.persistence.Dao;
import com.madx.finance.data.utils.factory.ConnectionFactory;

public aspect Village_Dao {
    declare parents: Village implements Dao<Village>;

    public void Village.insert() {
        Village.insertVillage(this);
    }

    public void Village.update() {
        Village.updateVillage(this);
    }

    public void Village.delete() {
        Village.deleteVillage(this.getVid());
    }

    public Village Village.getData() {
        return Village.getDataVillage(this.getVid());
    }

    public static void Village.insertVillage(Village village) {
        SqlSession session = ConnectionFactory.getSqlSessionFactory().openSession();
        VillageMapper mapper = session.getMapper(VillageMapper.class);
        mapper.insertVillage(village);
        session.commit();
        session.close();
    }

    public static void Village.updateVillage(Village village) {
        SqlSession session = ConnectionFactory.getSqlSessionFactory().openSession();
        VillageMapper mapper = session.getMapper(VillageMapper.class);
        mapper.updateVillage(village);
        session.commit();
        session.close();
    }

    public static void Village.deleteVillage(Integer id) {
        SqlSession session = ConnectionFactory.getSqlSessionFactory().openSession();
        VillageMapper mapper = session.getMapper(VillageMapper.class);
        mapper.deleteVillage(id);
        session.commit();
        session.close();
    }

    public static Village Village.getDataVillage(Integer id) {
        SqlSession session = ConnectionFactory.getSqlSessionFactory().openSession();
        VillageMapper mapper = session.getMapper(VillageMapper.class);
        Village village = mapper.selectVillage(id);
        session.close();
        return village;
    }
}

我尝试将Village_Dao.aj转换为带注释的版本Village_Dao_Java.java但没有成功。 我只是设法让类实现Dao,但我无法编写方法(在此文件中单独插入,更新e删除Village_Dao_Java.java)。

这是Village_Dao_Java.java的版本(仍未完整)(我读过这个link但我无法在这种情况下使用它):

import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.DeclareParents;

import com.madx.finance.data.utils.persistence.Dao;

@Aspect
public class Village_Dao_Java {

    @DeclareParents("com.madx.demo.Village")
    private Dao<Village> implementedInterface;
}

1 个答案:

答案 0 :(得分:2)

使用@AspectJ样式无法实现所需的功能,您需要使用更强大的本机语法。 (你为什么还要转换?)

这背后的原因是Java编译器只能将@DeclareParents转换为Village是您在方面中定义的任何接口实现的子类的形式,例如:< / p>

@Aspect
public class Village_Dao_Java {
    public static class VillageDao implements Dao<Village> {
        @Override
        public void insert() {
            Village.insertVillage(this);
        }

        @Override
        public void update() {
            Village.updateVillage(this);
        }

        @Override
        public void delete() {
            Village.deleteVillage(this.getVid());
        }

        public Village getData() {
            return getDataVillage(this.getVid());
        }

    }

    @DeclareParents(
        value = "de.scrum_master.app.Village",
        defaultImpl = VillageDao.class
    )
    private Dao<Village> villageDao;
}

但这种方法有几个问题:

  • 这些方法尝试从未来VillageDao子类Village访问静态方法,因此您无法在VillageDao中声明静态方法,但必须直接在Village中声明它们
  • 相反,如果你直接在VillageDao中声明它们,你可以打电话给他们,例如通过VillageDao.insertVillage(this),但签名public static void insertVillage(Village village)将不再适合,因为thisVillageDao,而不是自己的子类Village
  • 由于类似的原因,您无法拨打this.getVid(),因为thisVillageDao而不是Village,但getter方法在原始{{1}中有固定签名}。class。

等等。 Java编译器的功能不足以完成AspectJ编译器的功能:将代码编织到原始类文件中。

Ergo:请坚持使用原生语法。它不仅更强大,而且IMO也更具可读性。我永远不明白为什么这么多人试图将强大的AspectJ哄骗到糟糕的替代@AspectJ语法中。不知何故,他们似乎相信他们从纯Java语法中获益。我不同意。他们只是降低了技术手段和糟糕的语法,从未打算用于成熟的AOP。