JPA实现对Set集合的查询

User.java

/**  * A user.  */ @Entity @Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE) public class User  implements Serializable {     @Id     @GeneratedValue(strategy = GenerationType.AUTO)     private Long id;     @NotNull     @Size(min = 1, max = 50)     @Column(length = 50, unique = true, nullable = false)     private String login;     @NotNull     @Size(min = 5, max = 100)     @Column(length = 100)     @JsonSerialize(using = CustomPasswordSerializer.class)     private String password;     @Size(max = 50)     @Column(name = "first_name", length = 50)     private String firstName;     @Size(max = 50)     @Column(name = "last_name", length = 50)     private String lastName;        @ManyToMany     @JoinTable(         name = "JHI_USER_AUTHORITY",         joinColumns = {@JoinColumn(name = "user_id", referencedColumnName = "id")},         inverseJoinColumns = {@JoinColumn(name = "authority_name", referencedColumnName = "name")})     @Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)     private Set authorities = new HashSet<>();     public Long getId() {         return id;     }     public void setId(Long id) {         this.id = id;     }     public String getLogin() {         return login;     }     public void setLogin(String login) {         this.login = login;     }     public String getPassword() {         return password;     }     public void setPassword(String password) {         this.password = password;     }     public String getFirstName() {         return firstName;     }     public void setFirstName(String firstName) {         this.firstName = firstName;     }     public String getLastName() {         return lastName;     }     public void setLastName(String lastName) {         this.lastName = lastName;     }        public Set getAuthorities() {         return authorities;     }     public void setAuthorities(Set authorities) {         this.authorities = authorities;     }

Authority.java

/**  * An authority (a security role) used by Spring Security.  */ @Entity @Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE) public class Authority implements Serializable {     @NotNull     @Size(min = 0, max = 50)     @Id     @Column(length = 50)     private String name;     public Authority(String name) {         this.name = name;     }     public Authority() {     }     public String getName() {         return name;     }     public void setName(String name) {         this.name = name;     }     @Override     public boolean equals(Object o) {         if (this == o) {             return true;         }         if (o == null || getClass() != o.getClass()) {             return false;         }         Authority authority = (Authority) o;         if (name != null ? !name.equals(authority.name) : authority.name != null) {             return false;         }         return true;     }     @Override     public int hashCode() {         return name != null ? name.hashCode() : 0;     }     @Override     public String toString() {         return "Authority{" +             "name='" + name + '\'' +             "}";     } }

action类

/**  * REST controller for managing Order.  */ @RestController @RequestMapping("/api") public class OrderResource {     @RequestMapping(value = "/order/REPlist",             method = RequestMethod.GET,             produces = MediaType.APPLICATION_JSON_VALUE)     @Timed     public ResponseEntity> getREPlist() throws URISyntaxException{     log.debug( "REP list" );     List uList = this.userRepository.findAll(new Specification() { @Override public Predicate toPredicate(Root root,CriteriaQuery query, CriteriaBuilder cb) { Predicate predicate = cb.conjunction(); List> expressions = predicate.getExpressions(); SetJoin authoritySetJoin = root.join(root.getModel().getSet("authorities", Authority.class), JoinType.LEFT); expressions.add( cb.or( cb.equal(authoritySetJoin.get("name"), AuthoritiesConstants.ADMIN ) , cb.equal(authoritySetJoin.get("name"), AuthoritiesConstants.FINANCE ) , cb.equal(authoritySetJoin.get("name"), AuthoritiesConstants.SALES ) , cb.equal(authoritySetJoin.get("name"), AuthoritiesConstants.DATAM ) , cb.equal(authoritySetJoin.get("name"), AuthoritiesConstants.CS )   ) );                                 // 这里 AuthoritiesConstants 是各种权限（String 常量） return predicate; } });     HttpHeaders headers = PaginationUtil.generatePaginationHttpHeadersForFrontWeb(new PageInfo());         return new ResponseEntity>(uList,headers,HttpStatus.OK);     } }