Question

我正在尝试一些非常基本的网络服务。每当我尝试返回Prtnr对象时，我都会收到此异常。

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课程是：

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
    ...
}

PrtnrGeoInfo类是：

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

}

PrtnrGeoInfoId类是：

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互相升华。但是如何解决这个问题呢。在Struts 2和Spring的应用程序中，这个对象传递得很好。

控制器类如下：

@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TestTemplate {

    private static final long serialVersionUID = 1130201273334264152L;
    public static void main(String[] args){
        Prtnr partner = (Prtnr)new RestTemplate().getForObject("http://localhost:9080/respondersApp/testWs/partners/{id}", Prtnr.class, "1");
        System.out.println("partner name is : " + partner.getPrtnrNm());
    }
}

Answer 1

在此link中，您可以找到解决此问题的方法。

但是，我将在实践中粘贴解决方案。

这非常简单。假设您的数据库查询在没有JSON的情况下已经可以运行，您只需要这样做：

添加@JsonManagedReferenc e在关系的前面部分（即User.java类）：

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

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

 @Column(name="name")
 private String name;

 @ManyToMany
 @JoinTable(name="users_roles",joinColumns=@JoinColumn(name = "user_fk"),
 inverseJoinColumns=@JoinColumn(name = "role_fk"))
 @JsonManagedReference
 private Set<Role> roles = new HashSet<Role>();

...

在关系的后半部分添加@JsonBackReference（即Role.java类）：

@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>();

...

工作已经完成。如果你看看你的firebug日志，你会注意到无限递归循环已经消失。

Answer 2

当您尝试将实体类转换为JSON格式时，这是一种非常常见的情况。最简单的解决方案就是在反向映射上使用@JsonIgnore来打破循环。

Answer 3

您可以使用@JsonBackReference

在PrtnrGeoInfoId中注释Prtnr的第二个引用

Answer 4

这是一个常见的序列化问题。你必须在写入xml或json或对象流时使用@Transient来破坏这些依赖关系。

你必须在阅读时将它们连接回来。用这种方法完成接线

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

}

Answer 5

无限递归是由于以下原因：类Prtnr包含Set<PrtnrGeoInfo> prtnrGeoInfos，每个PrtnrGeoInfo包含PrtnrGeoInfoId id，而Prtnr partner又包含Prtnr。

因此，PrtnrGeoInfo - ＆gt; PrtnrGeoInfoId - ＆gt; Prtnr - ＆gt; {{1}}导致循环依赖，这在杰克逊试图进行POJO映射时会出现问题。

您需要删除此循环依赖项以修复此异常。

org.codehaus.jackson.map.JsonMappingException：无限递归（StackOverflowError）

5 个答案: