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JPA?@ManyToMany?報錯StackOverflowError的解決

更新時間：2021年12月06日 14:35:01 作者：浩騫

這篇文章主要介紹了JPA?@ManyToMany?報錯StackOverflowError的解決，具有很好的參考價值，希望對大家有所幫助。如有錯誤或未考慮完全的地方，望不吝賜教

JPA @ManyToMany 報錯StackOverflowError

在使用 SpringBoot + JPA 的@ManyToMany 遇到了如下報錯

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時，對應(yīng)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寫hash() equals(),toString() 方法。這樣添加和刪除的時候不會出現(xiàn)異常。否則出現(xiàn)循環(huán)的引用，不能刪除或stackOver；

不能刪除和添加成功，出現(xiàn)循環(huán)的主要問題在 toString()方法。此方法只能包含基本的元素，不要包含相應(yīng)的@ManyToMany 的對象。兩個類都是。這樣才會ok.

@Setter
@Getter
@Entity
public 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<Role> 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
@Entity
public 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<User>  users;
}

SpringJPA批量刪除引起的StackOverFlow

項目里有一處根據(jù)Id，批量刪除一些歷史數(shù)據(jù)的代碼(xxxRepository.deleteInBatch(list);)，發(fā)現(xiàn)傳入list過大時，出現(xiàn)棧溢出(StackOverFlowError) 。

解決方法

list切分成多份，循環(huán)批量刪除。

下面是簡單的了解一下執(zhí)行流程。

 deleteInBatch(Iterable<T> entities) 
/**
  點進(jìn)源碼 看看。
  org.springframework.data.jpa.repository.support.SimpleJpaRepository#deleteInBatch
*/
	@Transactional
	public void deleteInBatch(Iterable<T> entities) { 
		Assert.notNull(entities, "The given Iterable of entities not be null!"); 
		if (!entities.iterator().hasNext()) {
			return;
		} 
// 繼續(xù)跟蹤
		applyAndBind(getQueryString(DELETE_ALL_QUERY_STRING, entityInformation.getEntityName()), entities, em)
				.executeUpdate();
	}  
/**
 org.springframework.data.jpa.repository.query.QueryUtils#applyAndBind
*/ 
public static <T> Query applyAndBind(String queryString, Iterable<T> entities, EntityManager entityManager) {
   // ... 省略一些code
   // 最后會形成 delete from xx表  x(表別名) where x.id =? or x.id=?... 一條sql語句 
        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());
		}  
}

結(jié)合日志記錄的錯誤信息，進(jìn)入到org.hibernate.hql.internal.antlr.HqlSqlBaseWalker#logicalExpr 方法