个人技术总结

jpa基本使用

• Spring-data-jpa的基本介绍：JPA诞生的缘由是为了整合第三方ORM框架，建立一种标准的方式，百度百科说是JDK为了实现ORM的天下归一，目前也是在按照这个方向发展，但是还没能完全实现。在ORM框架中，Hibernate是一支很大的部队，使用很广泛，也很方便，能力也很强，同时Hibernate也是和JPA整合的比较良好，我们可以认为JPA是标准，事实上也是，JPA几乎都是接口，实现都是Hibernate在做，宏观上面看，在JPA的统一之下Hibernate很良好的运行。

• 配置文件结构

• <context:property-placeholder location="classpath:your-config.properties" ignore-unresolvable="true" />

  <context:component-scan base-package="your service package" />

  <aop:aspectj-autoproxy proxy-target-class="true" />

  <tx:annotation-driven transaction-manager="transactionManager" proxy-target-class="true" />

  <jpa:repositories base-package="your dao package" repository-impl-postfix="Impl" entity-manager-factory-ref="entityManagerFactory" transaction-manager-ref="transactionManager" />

  <tx:advice id="txAdvice" transaction-manager="transactionManager">
  tx:attributes
  <tx:method name="" />
  <tx:method name="get" read-only="true" />
  <tx:method name="find" read-only="true" />
  <tx:method name="select" read-only="true" />
  <tx:method name="delete" propagation="REQUIRED" />
  <tx:method name="update" propagation="REQUIRED" />
  <tx:method name="add" propagation="REQUIRED" />
  <tx:method name="insert" propagation="REQUIRED" />
  </tx:attributes>
  </tx:advice>

  aop:config
  <aop:pointcut id="allServiceMethod" expression="execution(* your service implements package..(..))" />
  <aop:advisor pointcut-ref="allServiceMethod" advice-ref="txAdvice" />
  </aop:config>

* 建立一个普通类UserRepositoryImpl来表示该类的实现类 * public class StudentRepositoryImpl {

@PersistenceContext
private EntityManager em;
@SuppressWarnings("unchecked")
public Page<Student> search(User user) {
    String dataSql = "select t from User t where 1 = 1";
    String countSql = "select count(t) from User t where 1 = 1";
    
    if(null != user && !StringUtils.isEmpty(user.getName())) {
        dataSql += " and t.name = ?1";
        countSql += " and t.name = ?1";
    }
    
    Query dataQuery = em.createQuery(dataSql);
    Query countQuery = em.createQuery(countSql);
    
    if(null != user && !StringUtils.isEmpty(user.getName())) {
        dataQuery.setParameter(1, user.getName());
        countQuery.setParameter(1, user.getName());
    }long totalSize = (long) countQuery.getSingleResult();
    Page<User> page = new Page();
    page.setTotalSize(totalSize);
    List<User> data = dataQuery.getResultList();
    page.setData(data);
    return page;
}

}

• 使用JPA的动态接口

• public interface JpaSpecificationExecutor {

  T findOne(Specification spec);

  List findAll(Specification spec);

  Page findAll(Specification spec, Pageable pageable);

  List findAll(Specification spec, Sort sort);

  long count(Specification spec);
  }