我正在用 Spring MVC 编写网络。我使用通用 DAO 编写了所有 DAO。现在我想重写我的服务类。我该如何写“通用服务”？
有我的 DAO：
/* ################################# DAO ################################ */
package net.example.com.dao;
import java.util.List;
public interface GenericDao<T> {
public T findById(int id);
public List<T> findAll();
public void update(T entity);
public void save(T entity);
public void delete(T entity);
}
/* ------------------------------------------------------ */
package net.example.com.dao;
import java.io.Serializable;
import java.util.List;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Scope;
@Scope("prototype")
public abstract class GenericHibernateDaoImpl<T extends Serializable> implements GenericDao<T> {
private Class<T> clazz;
@Autowired
private SessionFactory sessionFactory;
public final void setClazz(Class<T> clazzToSet) {
this.clazz = clazzToSet;
}
@SuppressWarnings("unchecked")
public T findById(int id) {
return (T) getCurrentSession().get(clazz, id);
}
@SuppressWarnings("unchecked")
public List<T> findAll() {
return getCurrentSession().createQuery("FROM " + clazz.getName()).list();
}
public void update(T entity) {
getCurrentSession().update(entity);
}
public void save(T entity) {
getCurrentSession().save(entity);
}
public void delete(T entity) {
getCurrentSession().delete(entity);
}
protected final Session getCurrentSession(){
return sessionFactory.getCurrentSession();
}
}
/* ------------------------------------------------------ */
package net.example.com.dao;
import net.example.com.entity.Country;
public interface CountryDao extends GenericDao<Country> {
public Country findByName(String name);
public Country findByCode(String code);
}
/* ------------------------------------------------------ */
package net.example.com.dao;
import org.springframework.stereotype.Repository;
import net.example.com.entity.Country;
@Repository
public class CountryDaoImpl extends GenericHibernateDaoImpl<Country> implements CountryDao {
@Override
public Country findByName(String name) {
return (Country) getCurrentSession()
.createQuery("FROM Country WHERE name = :name")
.setString("name", name).uniqueResult();
}
@Override
public Country findByCode(String code) {
return (Country) getCurrentSession()
.createQuery("FROM Country WHERE code = :code")
.setString("code", code).uniqueResult();
}
}
/* ################################# DAO ################################ */
和服务：
/* ################################# SERVICE ################################ */
package net.example.com.service;
import java.util.List;
public interface GenericManager<T> { // GenericManager<T> is the same as GenericDao<T>
public T findById(int id);
public List<T> findAll();
public void update(T entity);
public void save(T entity);
public void delete(T entity);
}
/* ------------------------------------------------------ */
package net.example.com.service;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import net.example.com.dao.GenericDao;
@Service
public abstract class GenericManagerImpl<T> implements GenericManager<T> {
@Autowired
protected GenericDao<T> dao;
@Override
public T findById(int id) {
return dao.findById(id);
}
@Override
public List<T> findAll() {
return dao.findAll();
}
@Override
public void update(T entity) {
dao.update(entity);
}
@Override
public void save(T entity) {
dao.save(entity);
}
@Override
public void delete(T entity) {
dao.delete(entity);
}
}
/* ------------------------------------------------------ */
package net.example.com.dao;
import net.example.com.entity.Country;
public interface CountryManager extends GenericDao<Country> { // CountryManager is the same as CountryDao
public Country findByName(String name);
public Country findByCode(String code);
}
/* ------------------------------------------------------ */
package net.example.com.service;
import java.util.List;
import javax.transaction.Transactional;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import net.example.com.dao.CountryDao;
import net.example.com.entity.Country;
@Service
@Transactional
public class CountryManagerImpl extends GenericManagerImpl<Country> implements CountryManager {
@Override
public List<Country> findAll() {
return dao.findAll();
}
public Country findById(int id) {
return dao.findById(id);
}
@Override
public Country findByName(String name) {
return dao.findByName(name); // compiler (and Eclipse) do not see findByName !!!!!!!!!
}
@Override
public Country findByCode(String code) {
return dao.findByCode(code); // compiler (and Eclipse) do not see findByCode !!!!!!!!!
}
@Override
public void save(Country country) {
dao.save(country);
}
@Override
public void delete(Country country) {
dao.delete(country);
}
@Override
public void update(Country country) {
dao.update(country);
}
}
/* ------------------------------------------------------ */
/* ################################# SERVICE ################################ */
编译器（和 Eclipse）看不到findByName和findByCode方法。我明白为什么。但是我该如何重写呢？