springboot之jpa支持

导入相关pom依赖

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

application.yml文件配置

spring:
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: true

自动建表相关代码

@Entity
@Table(name = "t_springbootjpa_book")
public class Book {
    @Id
    @GeneratedValue
    private Integer bid;
    @Column(length = 100)
    private String bname;
    @Column
    private Float price;

jpa值增删改查

 * 只要继承JpaRepository，通常所用的增删查改方法都有
 *  第一个参数：操作的实体类
 *  第二个参数：实体类对应数据表的主键
 */
public interface JpaDao extends JpaRepository<Book, Integer> {
}

controller层

@Autowired
    private JpaDao jpaDao;

    @RequestMapping("/add")
    public String add(Book book){
        jpaDao.save(book);
        return "success";
    }

    @RequestMapping("/edit")
    public String edit(Book book){
        jpaDao.save(book);
        return "success";
    }

    @RequestMapping("/del")
    public String del(Book book){
        jpaDao.delete(book);
        return "success";
    }

    @RequestMapping("/getOne")
    public Book getOne(Integer bid){
//        会出现懒加载问题：org.hibernate.LazyInitializationException: could not initialize proxy - no Session
//        return jpaDao.getOne(bid);
        return jpaDao.findById(bid).get();
    }

    @RequestMapping("/getAll")
    public List<Book> getAll(){
        return jpaDao.findAll();
    }

浏览器输入请求进行测试

http://localhost:8080/springboot/jpa/getOne?bid=8

http://localhost:8080/springboot/jpa/getAll

http://localhost:8080/springboot/jpa/add?bname=哈哈ha&price=99

http://localhost:8080/springboot/jpa/add?bname=嗯哼&price=12&bid=11

http://localhost:8080/springboot/jpa/del?bid=11

jpa值复杂查询

dao层

 *  要使用高级查询必须继承
 * org.springframework.data.jpa.repository.JpaSpecificationExecutor<T>接口
 */
public interface JpaDao extends JpaRepository<Book, Integer>, JpaSpecificationExecutor<Book> {
}

controller层

@RequestMapping("/getCondition")
    public  List<Book> getCondition(Book book){
        return jpaDao.findAll(new Specification<Book>() {
            @Override
            public Predicate toPredicate(Root<Book> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
                Predicate predicate = criteriaBuilder.conjunction();
                if(book != null){
                    if(null != book.getBname() && !"".equals(book.getBname())){
                        predicate.getExpressions().add(criteriaBuilder.like(root.get("bname"),"%"+book.getBname()+"%"));
                    }
                }
                return predicate;
            }
        });
    }