JPA双向Onetomany json无限循环

Question

该特定环境下的程序\xef\xbc\x9a\n EJB3.0 + JPA + jersey Web Service

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第一个实体：

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@Entity\n@Table(name = "student_by_test_yao")\n\npublic class StudentTest implements Serializable {\n    @Id\n    @GeneratedValue\n    private Integer id;\n    private String name;\n\n    @ManyToOne\n    @JoinColumn(name = "class_id")\n    private ClassTest classes;\n\n    public StudentTest() {}\n}\n

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第二实体：

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@Entity\n@Table(name = "class_by_test_yao")\npublic class ClassTest implements Serializable{\n    @Id\n    @GeneratedValue\n    private Integer id;\n    private String name;\n\n    @OneToMany(mappedBy = "classes",cascade = CascadeType.ALL, fetch=FetchType.EAGER)\n    private List<StudentTest> students;\n\n    public ClassTest() {}\n}\n

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当我拿到ClassTest的学生名单时。\n例外是：

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com.fasterxml.jackson.databind.JsonMappingException:\nInfinite recursion (StackOverflowError)\n

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如果我更改获取 FetchType.LAZY 异常是：

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org.hibernate.LazyInitializationException: \nfailed to lazily initialize a collection of role: \ncn.gomro.mid.core.biz.goods.test.ClassTest.students, \ncould not initialize proxy - no Session\n

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如何解决我的问题？

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Answer 1

@JsonIgnore
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "userId")
private User user;

确实有效。我刚刚在双向 @ManyToOne 映射上尝试过。它固定了

com.fasterxml.jackson.databind.JsonMappingException：无限递归（StackOverflowError）

Answer 2

尝试将@JsonIgnore注释添加到字段之一以避免循环