Spring data jpa的使用与详解(复杂动态查询及分页，排序)

Predicate toPredicate(Root<T> root, CriteriaQuery<?> query, CriteriaBuilder cb); 

@Data
public class AccountRequest {

  //从第几页开始
  private Integer page;

  //每一页查询多少
  private Integer limit;

  private String id;

  private String name;

  private String pwd;

  private String email;

  private Integer[] types;

}

@Data
@Entity
@Table(name = "account")
@ToString
@EntityListeners(AuditingEntityListener.class)
public class Account {

  @Id
  @GenericGenerator(name = "idGenerator", strategy = "uuid")
  @GeneratedValue(generator = "idGenerator")
  private String id;

  @Column(name = "username", unique = true, nullable = false, length = 64)
  private String username;

  @Column(name = "password", nullable = false, length = 64)
  private String password;

  @Column(name = "email", length = 64)
  private String email;

  @Column(name = "type")
  private Short type;

  @CreatedDate
  @Column(name = "create_time", nullable = false)
  private LocalDateTime createTime;

}

public interface AccountRepository extends JpaRepository<Account,String>, JpaSpecificationExecutor<Account> {}

@Autowired
  private AccountRepository repository;


  @PostMapping("/get")
  public List<Account> get(@RequestBody AccountRequest request){
    Specification<Account> specification = new Specification<Account>() {

      @Override
      public Predicate toPredicate(Root<Account> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder builder) {
        //所有的断言 及条件
        List<Predicate> predicates = new ArrayList<>();
        //精确匹配id pwd
        if (request.getId() != null) {
          predicates.add(builder.equal(root.get("id"), request.getId()));
        }
        if (request.getPwd() != null) {
          predicates.add(builder.equal(root.get("password"), request.getPwd()));
        }
        //模糊搜索 name
        if (request.getName() != null && !request.getName().equals("")) {
          predicates.add(builder.like(root.get("username"), "%" + request.getName() + "%"));
        }
        if (request.getEmail() != null && !request.getEmail().equals("")) {
          predicates.add(builder.like(root.get("email"), "%" + request.getEmail() + "%"));
        }
        //in范围查询
        if (request.getTypes() != null) {
          CriteriaBuilder.In<Object> types = builder.in(root.get("type"));
          for (Integer type : request.getTypes()) {
            types = types.value(type);
          }
          predicates.add(types);
        }
        return builder.and(predicates.toArray(new Predicate[predicates.size()]));
      }
    };
    List<Account> accounts = repository.findAll(specification);

    return accounts;
  }

@PostMapping("/page")
  public List<Account> getPage(@RequestBody AccountRequest request){

    Specification<Account> specification = new Specification<Account>() {
      @Override
      public Predicate toPredicate(Root<Account> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
        List<Predicate> predicates = new ArrayList<>();
        //do anything
        return criteriaBuilder.and(predicates.toArray(new Predicate[predicates.size()]));
      }
    };
    //表示通过createTime进行 ASC排序
    PageRequest page = new PageRequest(request.getPage() - 1, request.getLimit(), Sort.Direction.ASC, "createTime");
    Page<Account> pageInfo = repository.findAll(specification, page);

    return pageInfo.getContent();
  }

@Repository
public interface AccountRepository extends JpaRepository<Account,String>, JpaSpecificationExecutor<Account> , PagingAndSortingRepository<Account,String> {
  Page<Account> findByAge(int age, Pageable pageable);
}

//显示第1页每页显示3条
PageRequest pr = new PageRequest(1,3);
//根据年龄进行查询
Page<Account> stus = accountPageRepository.findByAge(22,pr); 
 

List<Account> findByPwd(String pwd, Sort sort);

//设置排序方式为username降序
List<Account> accs = accountPageRepository.findByAge("123456",new Sort(Sort.Direction.DESC,"username"));
//设置排序以username和type进行升序
acc = accountPageRepository.findByAge("123456",new Sort(Sort.Direction.ASC,"username","type"));
//设置排序方式以name升序，以address降序
Sort sort = new Sort(new Sort.Order(Sort.Direction.ASC,"name"),new Sort.Order(Sort.Direction.DESC,"type"));
accs = accountPageRepository.findByAge("123456",sort);