JPA / Hibernate双向多对一导致StackOverflowException [英] JPA/Hibernate bidirectional many-to-one results in StackOverflowException
问题描述
我有实体User和GrantedRole,它们具有双向的一对多关系。
I have entities User and GrantedRole that have a bidirectional one-to-many relation.
当我尝试将GrantedRole添加到Set in User时,有没有异常抛出,但是当我为User调试变量时,GrantedRole对象的描述为
When I try to add a GrantedRole to the Set in User, there is no exception thrown, but when I debug the variables for the User and GrantedRole object have a description that reads
com.sun.jdi.InvocationException发生了调用方法。
com.sun.jdi.InvocationException occurred invoking method.
调试时可以读取变量的不同字段,但是当我选择User中的角色字段时GrantedRole中的用户字段我得到与上面相同的描述。
当我进入用户的Set of GrantedRole时,我最终找到以下描述:
The different fields for the variables can be read while debugging, but when I select the roles field in User or the user field in GrantedRole I get the same description as above. When I go into the Set of GrantedRole in user, I eventually find the following description:
详细格式化程序错误:
发生异常:java.lang.StackOverflowError
Detail formatter error: An exception occurred: java.lang.StackOverflowError
我的代码:
public class User {
private Set<GrantedRole> roles = new HashSet<GrantedRole>();
public User() {
super();
}
public User(String name, String password) {
this.name = name;
this.password = password;
}
@OneToMany(fetch = FetchType.EAGER, mappedBy = "user")
public Set<GrantedRole> getRoles() {
return roles;
}
public void setRoles(Set<GrantedRole> roles) {
this.roles = roles;
}
// equals and hashCode are based on username
// toString is based on all fields
}
public class GrantedRole {
private user user;
public GrantedRole() {
super();
}
public GrantedRole(User user, Role role, Organization organization) {
this.user = user;
this.role = role;
this.organization = organization;
}
@ManyToOne
@NotNull
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
// equals and hashCode are based on all fields
// toString was based on all fields, I've changed it to not include User.
}
public class Test {
public void testStuff() {
User user = new User("name");
GrantedRole role = new GrantedRole(user, "role"); //this sets the user field
user.getRoles().add(role); //doesn't throw Exception, but debugging shows InvocationTargetException and StackOverflowException
System.out.println(user.getRoles()); //throws StackOverflowException, as I would expect
}
}
它是我的理解是我应该能够以这种方式建立双向关系。我阅读了多个教程,喜欢这个 ,我不知道我做了什么不同导致.add(角色)出错。
It was my understanding that I should be able to set up a bidirectional relation in this way. I read multiple tutorials, like this one, and I don´t see what I am doing differently to cause the .add(role) to go wrong.
我遗漏了一些简单的代码,如果需要的话我很乐意提供。我没有制作代码来确保该用户引用一个引用用户的GrantedRole作为回报,但我认为这与我遇到的问题无关。
I left out some trivial code, if it is needed I will gladly provide it. I haven't made code to ensure that a GrantedRole with a reference to a User is referenced by that user in return, but I think that is not relevant for the problem I'm having.
推荐答案
所以,我只是愚蠢而且在toString()方法中进行了递归调用。
User.toString()尝试打印角色,GrantedRole.toString()尝试打印用户。
So, I was just being stupid and had a recursive call in the toString() methods. User.toString() tried to print the roles, and GrantedRole.toString() tried to print the user.
我通过改变GrantedRole来修复它。 toString()打印user.getUsername(),从而打破循环。
I fixed it by altering the GrantedRole.toString() to print user.getUsername(), thus breaking the cycle.
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