通用Service设计

import java.util.List;

public interface BaseService<M extends java.io.Serializable, PK extends java.io.Serializable> {

	public M findById(PK id);
	
	public List<M> findByHQL(String hql, Object... params);

	public void update(M entity);
	
	public PK save(M entity);

	public void saveOrUpdate(M entity);

	public void delete(M entity);
	
	public void deleteById(PK id);
}

import java.util.List;
import org.springframework.transaction.annotation.Transactional;

@Transactional
public abstract class BaseServiceImpl<M extends java.io.Serializable, PK extends java.io.Serializable> implements BaseService<M, PK> {

	//这里不能使用spring3的ioc注入，泛型只在编译期间有效，所以必须在编译时决定类型。
	//@Autowired spring4新特性泛型注入可以实现
	//protected BaseDao<M, PK> dao;
	/*public void setDao(BaseDao<M, PK> dao) {
		this.dao = dao;
	}*/
	
	protected BaseDao<M, PK> dao;
	
	@Override
	public M findById(PK id) {
		
		return this.dao.findById(id);
	}

	@Override
	public List<M> findByHQL(String hql, Object... params) {
		
		return this.dao.findByHQL(hql, params);
	}

	@Override
	public void update(M entity) {
		
		this.dao.update(entity);
	}

	@Override
	public PK save(M entity) {
		
		PK id = this.dao.save(entity);
		/* test rollback
		if (id != null)
			throw new RuntimeException("runtime exception throw from " + this.getClass().getSimpleName() + ".save()");
		*/
		return id;
	}

	@Override
	public void saveOrUpdate(M entity) {
		
		this.dao.saveOrUpdate(entity);
	}

	@Override
	public void delete(M entity) {
		
		this.dao.delete(entity);
	}
	
	@Override
	public void deleteById(PK id) {
		
		this.dao.delete(this.findById(id));
	}

}

///////////////////////////////////////////////////////////////
public interface StudentService extends BaseService<Student, String> {

	/**
	 * 添加 IBaseService 没有定义的方法
	 */
	public void serviceMethod();
}

import javax.annotation.Resource; 
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;  

@Service("studentService")
@Transactional
public class StudentServiceImpl extends BaseServiceImpl<Student, String> implements
		StudentService {

	protected StudentDao studentDao;
	@Resource(name = "studentDao")
	public void setStudentDao(StudentDao dao) {
		super.dao = dao;
		this.studentDao = dao;
	}
	
	@Override
	public void serviceMethod() {

		this.studentDao.studentMethod();
	}
}