Spring JPA Json循环依赖的问题分析

ゝ一纸荒年。 2023-07-24 02:45 5阅读 0赞

## 背景 ##

Lombok中的@Data，其等价于：  
setter/getter、equals、canEqual、hashCode、toString

在Spring Data JPA中，对于存在双向依赖的情况，类似如下：

@Entity
    @Table(name="t_user")
    @Data
    public class User {
          private Long id;
          private String name;
          
         @OneToOne(cascade=CascadeType.ALL, fetch=FetchType.LAZY)
    	 @JoinColumn(name="user_ext_id", referencedColumnName="id")
          private UserExtEntity userExtEntity;
    }
    
    @Entity
    @Table(name="t_user")
    @Data
    public class UserExtEntity {
          private String info;
    
        @OneToOne(mappedBy = "userExtEntity")
        private UserEntity userEntity;
    }

## 问题描述 ##

测试代码：

@Test
    public void testJsonInfinite() {
          List<UserEntity> userEntities = this.userRepository.findAll();
    
    		log.info("User entities:{}", Arrays.toString(userEntities.toArray()))； 
    }

异常信息如下：

java.lang.StackOverflowError
    	at sun.misc.FloatingDecimal$BinaryToASCIIBuffer.dtoa(FloatingDecimal.java:431)
    	at sun.misc.FloatingDecimal$BinaryToASCIIBuffer.access$100(FloatingDecimal.java:259)
    	at sun.misc.FloatingDecimal.getBinaryToASCIIConverter(FloatingDecimal.java:1825)
    	at sun.misc.FloatingDecimal.toJavaFormatString(FloatingDecimal.java:80)
    	at java.lang.Float.toString(Float.java:206)
    	at java.lang.Float.toString(Float.java:568)
    	at java.lang.String.valueOf(String.java:2994)
    	at java.lang.StringBuilder.append(StringBuilder.java:131)
    	at org.spb.data.dao.entity.UserExtEntity.toString(UserExtEntity.java:16)
    	at sun.reflect.GeneratedMethodAccessor38.invoke(Unknown Source)
    	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    	at java.lang.reflect.Method.invoke(Method.java:498)
    	at org.hibernate.proxy.pojo.bytebuddy.ByteBuddyInterceptor.intercept(ByteBuddyInterceptor.java:56)
    	at org.hibernate.proxy.ProxyConfiguration$InterceptorDispatcher.intercept(ProxyConfiguration.java:95)
    	at org.spb.data.dao.entity.UserExtEntity$HibernateProxy$OYDwMbzs.toString(Unknown Source)
    	at java.lang.String.valueOf(String.java:2994)
    	at java.lang.StringBuilder.append(StringBuilder.java:131)
    	at org.spb.data.dao.entity.UserEntity.toString(UserEntity.java:23)
    	at java.lang.String.valueOf(String.java:2994)
    	at java.lang.StringBuilder.append(StringBuilder.java:131)
    	at org.spb.data.dao.entity.UserExtEntity.toString(UserExtEntity.java:16)
    	at sun.reflect.GeneratedMethodAccessor38.invoke(Unknown Source)
    	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    	at java.lang.reflect.Method.invoke(Method.java:498)
    	at org.hibernate.proxy.pojo.bytebuddy.ByteBuddyInterceptor.intercept(ByteBuddyInterceptor.java:56)
    	at org.hibernate.proxy.ProxyConfiguration$InterceptorDispatcher.intercept(ProxyConfiguration.java:95)
    	at org.spb.data.dao.entity.UserExtEntity$HibernateProxy$OYDwMbzs.toString(Unknown Source)
    	at java.lang.String.valueOf(String.java:2994)
    	at java.lang.StringBuilder.append(StringBuilder.java:131)
    	at org.spb.data.dao.entity.UserEntity.toString(UserEntity.java:23)
    	at java.lang.String.valueOf(String.java:2994)
    	at java.lang.StringBuilder.append(StringBuilder.java:131)
    	at org.spb.data.dao.entity.UserExtEntity.toString(UserExtEntity.java:16)
    	at sun.reflect.GeneratedMethodAccessor38.invoke(Unknown Source)
    	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    	at java.lang.reflect.Method.invoke(Method.java:498)
    	at org.hibernate.proxy.pojo.bytebuddy.ByteBuddyInterceptor.intercept(ByteBuddyInterceptor.java:56)
    	at org.hibernate.proxy.ProxyConfiguration$InterceptorDispatcher.intercept(ProxyConfiguration.java:95)
    	at org.spb.data.dao.entity.UserExtEntity$HibernateProxy$OYDwMbzs.toString(Unknown Source)
    	at java.lang.String.valueOf(String.java:2994)
    	at java.lang.StringBuilder.append(StringBuilder.java:131)
    	at org.spb.data.dao.entity.UserEntity.toString(UserEntity.java:23)
    	at java.lang.String.valueOf(String.java:2994)
    	at java.lang.StringBuilder.append(StringBuilder.java:131)
    	at org.spb.data.dao.entity.UserExtEntity.toString(UserExtEntity.java:16)
    	at sun.reflect.GeneratedMethodAccessor38.invoke(Unknown Source)
    	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    	at java.lang.reflect.Method.invoke(Method.java:498)
    	at org.hibernate.proxy.pojo.bytebuddy.ByteBuddyInterceptor.intercept(ByteBuddyInterceptor.java:56)
    	at org.hibernate.proxy.ProxyConfiguration$InterceptorDispatcher.intercept(ProxyConfiguration.java:95)
    	at org.spb.data.dao.entity.UserExtEntity$HibernateProxy$OYDwMbzs.toString(Unknown Source)
    	at java.lang.String.valueOf(String.java:2994)
    	at java.lang.StringBuilder.append(StringBuilder.java:131)
    	at org.spb.data.dao.entity.UserEntity.toString(UserEntity.java:23)

使用了解决循环依赖的策略：

1.  @JsonManagedReference/ @JsonBackReference
2.  @JsonIdentityInfo(  
    generator = ObjectIdGenerators.PropertyGenerator.class,  
    property = “id”)

但是上述的问题依旧。 但是在简单的Case中是可以正常工作的.

## 解决办法 ##

移除其中一个@Data方法，其中默认重写了@ToString的方法，导致上述的两个方法不起作用，从异常日志上看，应该是有Proxy代理相关的内容引发的。

解决的代码：

@Entity
    @Table(name="t_user")
    @Data
    public class User {
          private Long id;
          private String name;
          
          @JsonManagedReference
         @OneToOne(cascade=CascadeType.ALL, fetch=FetchType.LAZY)
    	 @JoinColumn(name="user_ext_id", referencedColumnName="id")
          private UserExtEntity userExtEntity;
    }
    
    @Entity
    @Table(name="t_user")
    @Getter
    @Setter
    public class UserExtEntity {
          private String info;
    
       @JsonBackReference
        @OneToOne(mappedBy = "userExtEntity")
        private UserEntity userEntity;
    }