JPA @ManyToMany 报错StackOverflowError的解决_java
2022-03-01
目录
- JPA @ManyToMany 报错StackOverflowError
- SpringJPA批量删除引起的StackOverFlow
- 解决方法
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
@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<T> entities)
/**
点进源码 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;
}
// 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 <T> Query applyAndBind(String queryString, Iterable<T> 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
下面贴一下调用栈
org.hibernate.hql.internal.antlr.HqlSqlBaseWalker#deleteStatement 方法中 whereClause()调用到了logicalExpr 方法。
由下图可知，该方法在①处递归调用自身，会不断的创建栈帧，当超出栈深度或者超出栈的大小后，会爆出 栈溢出。
至于① 处怎么跳出继续执行后面的代码，还没研究，有知道的小伙伴请指教，不正确的地方也请指正。
