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JPA @ManyToMany报错怎么解决

发表于：2024-10-04 作者：千家信息网编辑

千家信息网最后更新 2024年10月04日，本篇内容主要讲解"JPA @ManyToMany报错怎么解决"，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习"JPA @ManyToMany报错怎么解决"吧!

千家信息网最后更新 2024年10月04日JPA @ManyToMany报错怎么解决

本篇内容主要讲解"JPA @ManyToMany报错怎么解决"，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习"JPA @ManyToMany报错怎么解决"吧!

JPA @ManyToMany 报错StackOverflowError

在使用 SpringBoot + JPA 的@ManyToMany 遇到了如下报错

java.lang.StackOverflowError: null

2021-02-07 10:59:59.490 ERROR 100440 --- [io-20012-exec-3] o.a.c.c.C.[.[.[/].[dispatcherServlet]:
Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed;
nested exception is org.springframework.http.converter.HttpMessageNotWritableException:
Could not write JSON: Infinite recursion (StackOverflowError);
nested exception is com.fasterxml.jackson.databind.JsonMappingException:
Infinite recursion (StackOverflowError) (through reference chain:
com.xxx.entity.boem.EquipmentManage["dataPublishes"]->org.hibernate.collection.internal.PersistentSet[0]
->com.xxx.entity.bods.DataPublish["equipmentManages"]->org.hibernate.collection.internal.PersistentBag[0]
->com.xxx.entity.boem.EquipmentManage["dataPublishes"]->org.hibernate.collection.internal.PersistentSet[0]
->com.xxx.entity.bods.DataPublish["equipmentManages"]->org.hibernate.collection.internal.PersistentBag[0]
->com.xxx.entity.boem.EquipmentManage["dataPublishes"]->org.hibernate.collection.internal.PersistentSet[0]
->.......
..........

注意：

使用@ManyToMany时，对应的Entity不可使用lombok 的@Data 注解。使用@Setter 、@Getter注解。主要原因是要自己覆写hash() equals(),toString() 方法。这样添加和删除的时候不会出现异常。否则出现循环的引用，不能删除或stackOver；

不能删除和添加成功，出现循环的主要问题在 toString()方法。此方法只能包含基本的元素，不要包含相应的@ManyToMany 的对象。两个类都是。这样才会ok.

@Setter@Getter@Entitypublic class User {    @Id    @GenericGenerator(name="jpauuid",strategy = "org.hibernate.id.UUIDGenerator")    @GeneratedValue(generator = "jpauuid")    @Column(length = 32,nullable = false)    private String  id;    @Column(length = 30)    private String username;    @ManyToMany(cascade = CascadeType.REFRESH,mappedBy = "users")    private Set roles;    @Override    public boolean equals(Object o) {        if (this == o) return true;        if (o == null || getClass() != o.getClass()) return false;        User user = (User) o;        return id.equals(user.id) &&                username.equals(user.username) &&                roles.equals(user.roles);    }    @Override    public int hashCode() {        return Objects.hash(id, username, roles);    }    @Override    public String toString() {        return "User{" +                "id='" + id + '\'' +                ", username='" + username + '\'' +                ", roles=" + roles +                '}';    }}

@Setter@Getter@Entitypublic class Role {    @Id    @GeneratedValue(strategy = GenerationType.AUTO)    private Integer id;    @Column(length = 30)    private String  name;    @ManyToMany(cascade = CascadeType.REFRESH)    @JoinTable(name = "user_role",joinColumns = @JoinColumn(name = "role_id"),inverseJoinColumns = @JoinColumn(name="user_id"))    private Set  users;}

SpringJPA批量删除引起的StackOverFlow

项目里有一处根据Id，批量删除一些历史数据的代码(xxxRepository.deleteInBatch(list);)，发现传入list过大时，出现栈溢出(StackOverFlowError) 。

解决方法

list切分成多份，循环批量删除。

下面是简单的了解一下执行流程。

 deleteInBatch(Iterable entities) /**  点进源码 看看。  org.springframework.data.jpa.repository.support.SimpleJpaRepository#deleteInBatch*/        @Transactional        public void deleteInBatch(Iterable entities) {                 Assert.notNull(entities, "The given Iterable of entities not be null!");                 if (!entities.iterator().hasNext()) {                        return;                } // 继续跟踪                applyAndBind(getQueryString(DELETE_ALL_QUERY_STRING, entityInformation.getEntityName()), entities, em)                                .executeUpdate();        }  /** org.springframework.data.jpa.repository.query.QueryUtils#applyAndBind*/ public static  Query applyAndBind(String queryString, Iterable entities, EntityManager entityManager) {   // ... 省略一些code   // 最后会形成 delete from xx表  x(表别名) where x.id =? or x.id=?... 一条sql语句         String alias = detectAlias(queryString);                StringBuilder builder = new StringBuilder(queryString);                builder.append(" where");                 int i = 0;                 while (iterator.hasNext()) {                         iterator.next();                         builder.append(String.format(" %s = ?%d", alias, ++i));                         if (iterator.hasNext()) {                                builder.append(" or");                        }                }                 Query query = entityManager.createQuery(builder.toString());                 iterator = entities.iterator();                i = 0;                 while (iterator.hasNext()) {                        query.setParameter(++i, iterator.next());                }  }

结合日志记录的错误信息，进入到org.hibernate.hql.internal.antlr.HqlSqlBaseWalker#logicalExpr 方法