Java org.codehaus.jackson.map.JsonMappingException:无限递归（StackOverflower错误）

我正在尝试一些非常基本的Web服务。每次尝试返回Prtnr对象时都会出现此异常

Uncaught exception thrown in one of the service methods of the servlet: spitter. Exception thrown : 
org.codehaus.jackson.map.JsonMappingException: Infinite recursion (StackOverflowError) 
(through reference chain: org.hibernate.collection.PersistentSet[0]->org.abc.dvo.PrtnrGeoInfo["id"]->org.abc.dvo.PrtnrGeoInfoId["partner"]->
org.abc.dvo.Prtnr["prtnrGeoInfos"]->org.hibernate.collection.PersistentSet[0]->org.abc.dvo.PrtnrGeoInfo["id"]->org.abc.dvo.PrtnrGeoInfoId["partner"]->
org.abc.dvo.Prtnr["prtnrGeoInfos"]->org.hibernate.collection.PersistentSet[0]->org.abc.dvo.PrtnrGeoInfo["id"]->org.abc.dvo.PrtnrGeoInfoId["partner"]->
org.abc.dvo.Prtnr["prtnrGeoInfos"]->org.hibernate.collection.PersistentSet[0]->org.abc.dvo.PrtnrGeoInfo["id"]->org.abc.dvo.PrtnrGeoInfoId["partner"]->
...
    at org.codehaus.jackson.map.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:164)
    at org.codehaus.jackson.map.ser.BeanSerializer.serialize(BeanSerializer.java:112)
    at org.codehaus.jackson.map.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:446)
    at org.codehaus.jackson.map.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:150)
    ...

Prtnr类别为：

public class Prtnr implements Cloneable, java.io.Serializable {

    private static final long serialVersionUID = 201207021420600052L;
    private Integer prtnrId;
    private String creatUserId;
    private Date creatTs;
    private String updtUserId;
    private Date updtTs;
    private String prtnrNm;
    private Integer cncilNum;
    private Character prtnrTypCd;
    private Set<PrtnrGeoInfo> prtnrGeoInfos = new HashSet<PrtnrGeoInfo>(0);
    private Set<PrtnrDtl> prtnrDtls = new HashSet<PrtnrDtl>(0);
    private Set<SuplyDtl> suplyDtls = new HashSet<SuplyDtl>(0);
    private Set<TrnsprtDtl> trnsprtDtls = new HashSet<TrnsprtDtl>(0);
    private Set<PrtnrFacil> prtnrFacils = new HashSet<PrtnrFacil>(0);
    private Set<PrtnrHumanResrc> prtnrHumanResrcs = new HashSet<PrtnrHumanResrc>(0);
    .....
    .....
    Getters and setters for these properties
    ...
}

public class PrtnrGeoInfo implements java.io.Serializable {
    private PrtnrGeoInfoId id = new PrtnrGeoInfoId();
    private String creatUserId;
    private Date creatTs;
    private String updtUserId;
    private Date updtTs;

    Getters and setters for these properties

}

public class PrtnrGeoInfoId implements java.io.Serializable {   
    private Prtnr partner;
    private GeoSegment geoSegment;
    private static final long serialVersionUID = 201207060857580050L;

    Getters and setters for these properties
}

PrtnrGeoInfoId类是：

public class Prtnr implements Cloneable, java.io.Serializable {

    private static final long serialVersionUID = 201207021420600052L;
    private Integer prtnrId;
    private String creatUserId;
    private Date creatTs;
    private String updtUserId;
    private Date updtTs;
    private String prtnrNm;
    private Integer cncilNum;
    private Character prtnrTypCd;
    private Set<PrtnrGeoInfo> prtnrGeoInfos = new HashSet<PrtnrGeoInfo>(0);
    private Set<PrtnrDtl> prtnrDtls = new HashSet<PrtnrDtl>(0);
    private Set<SuplyDtl> suplyDtls = new HashSet<SuplyDtl>(0);
    private Set<TrnsprtDtl> trnsprtDtls = new HashSet<TrnsprtDtl>(0);
    private Set<PrtnrFacil> prtnrFacils = new HashSet<PrtnrFacil>(0);
    private Set<PrtnrHumanResrc> prtnrHumanResrcs = new HashSet<PrtnrHumanResrc>(0);
    .....
    .....
    Getters and setters for these properties
    ...
}

public class PrtnrGeoInfo implements java.io.Serializable {
    private PrtnrGeoInfoId id = new PrtnrGeoInfoId();
    private String creatUserId;
    private Date creatTs;
    private String updtUserId;
    private Date updtTs;

    Getters and setters for these properties

}

public class PrtnrGeoInfoId implements java.io.Serializable {   
    private Prtnr partner;
    private GeoSegment geoSegment;
    private static final long serialVersionUID = 201207060857580050L;

    Getters and setters for these properties
}

我相信这是因为班级之间相互重复。但如何解决这个问题呢。在Struts 2和Spring应用程序中，这个对象可以很好地传递

控制器类如下所示：

@Controller
@RequestMapping("/partners")
public class PartnerController {
    @RequestMapping(value="/{id}", method=RequestMethod.GET, headers ={"Accept=text/xml,application/json"})
    @ResponseBody
    public Prtnr getPartner(@PathVariable("id") String id) throws Exception{
        Prtnr partner = null;
        try{
            partner = partnerService.getPartnerById(Integer.valueOf(id));
                System.out.println("******* Test message " );
        }catch(Exception ex){
            System.out.println("******* Exception thrown ... " + ex.getMessage());
        }

        return partner;
    }
}

调用类是 公共类测试模板 {

---

无限递归的原因如下： 类

Prtnr

包含

Set prtnrGeoInfos

，每个

PrtnrGeoInfo

包含

PrtnrGeoInfoId id

，后者依次包含

Prtnr合作伙伴

因此，

Prtnr

->

PrtnrGeoInfo

->

PrtnrGeoInfoId

->

Prtnr

，在Jackson尝试进行POJO映射时，会导致循环依赖性，这是一个问题

---

您需要删除此循环依赖项来修复此异常。

当您尝试将实体类转换为JSON格式时，这对我来说是一个非常常见的场景。最简单的解决方案就是在反向映射上使用

@JsonIgnore

来打破循环。

这是一个常规序列化问题。 在写入xml、json或对象流时，必须使用@Transient打破这些依赖关系

你必须在阅读时把它们接回去。 接线是用这种方法完成的

class Way{
list nodes;
addNode(Node node){
node.setWay(this);
nodes.add(node);

}

---

您可以使用

@JsonBackReference

在PrtnrGeoInfoId中注释Prtnr的第二个引用，在这里您可以找到解决方法

不过，下面我将实际粘贴解决方案

这很简单。假设您的数据库查询已经可以在没有JSON的情况下运行，那么您需要做的就是：

将

@jsonmanagedreference

e添加到关系的前向部分（即User.java类）：

---

工作完成了。如果您查看firebug日志，您会注意到无限递归循环已消失。

不幸的是，这是应用程序的要求，无法删除。如何克服循环依赖性问题？我猜您在

PrtnrGeoInfoId

中需要的可能是

Prtnr

的一些实例变量。克服这一问题的唯一方法是从

PrtnrGeoInfoId

中删除

Prtnr

。另外，请考虑是否可以用其他类替换该类。如果我们使用

@JsonIgnore

，那么我们无法获取关联的实体数据，我们如何获取该数据？

@Entity
public class Role implements java.io.Serializable {

 @Id 
 @GeneratedValue(strategy=GenerationType.IDENTITY)
 private int id;

 @ManyToMany(mappedBy="roles")
 @JsonBackReference
 private Set<User> users = new HashSet<User>();

...