无法写入 JSON:无限递归 (StackOverflowError)；嵌套异常弹簧靴 [英] Could not write JSON: Infinite recursion (StackOverflowError); nested exception spring boot
问题描述
这是我的区域控制器，当我在保存后尝试获取数据时出现错误，即使我尝试获取对象表单 getDistrict(Long id) 同样的罢工请提出一些建议，我spring环境中非常新:
This is my District Controller, when I try to fetch data after saving I get the error, even when I try get object form getDistrict(Long id) the same strikes please suggest some way, am very new at spring environment:
package com.gad.services;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import com.gad.repositories.DistrictMasterRepositories;
import com.gad.rmodels.Districtmaster;
import com.gad.rmodels.Statemaster;
@Service
public class DistricMasterServices {
@Autowired
DistrictMasterRepositories districtMasterRepositories;
@Autowired
StateMasterServices stateMasterServices;
List<Districtmaster> districtmaster;
public Iterable<Districtmaster> savenewdistrict(Long id,Districtmaster districtmaster_rec){
System.out.println(id);
Statemaster statemaster=null;
statemaster = stateMasterServices.getStateById(id);
System.out.println("savenewdistrict");
districtmaster_rec.setStatemaster(statemaster);
districtMasterRepositories.save(districtmaster_rec);
Iterable<Districtmaster>districtmaster2 = districtMasterRepositories.findAll();
return districtmaster2;
}
public Districtmaster getDistrict(Long id){
Districtmaster districtmaster = districtMasterRepositories.findOne(id);
return districtmaster;
}
}
状态的模型类:
package com.gad.rmodels;
import static javax.persistence.GenerationType.SEQUENCE;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.SequenceGenerator;
import javax.persistence.Table;
/**
* Statemaster generated by hbm2java
*/
@Entity
@Table(name="statemaster"
,schema="aop_gad_v1"
)
public class Statemaster implements java.io.Serializable {
private long id;
private String stateName;
private Set<Districtmaster> districtmasters = new HashSet<Districtmaster>(0);
public Statemaster() {
}
public Statemaster(long id) {
this.id = id;
}
public Statemaster(long id, String stateName, Set<Districtmaster> districtmasters) {
this.id = id;
this.stateName = stateName;
this.districtmasters = districtmasters;
}
@SequenceGenerator(name="generator_statemasterid", sequenceName="aop_gad_v1.gad_statemaster_seq")
@Id
@GeneratedValue(strategy=SEQUENCE, generator="generator_statemasterid")
@Column(name="id", unique=true, nullable=false)
public long getId() {
return this.id;
}
public void setId(long id) {
this.id = id;
}
@Column(name="state_name", length=20)
public String getStateName() {
return this.stateName;
}
public void setStateName(String stateName) {
this.stateName = stateName;
}
@OneToMany(cascade=CascadeType.ALL, fetch=FetchType.LAZY, mappedBy="statemaster")
public Set<Districtmaster> getDistrictmasters() {
return this.districtmasters;
}
public void setDistrictmasters(Set<Districtmaster> districtmasters) {
this.districtmasters = districtmasters;
}
}
区域模型:
package com.gad.rmodels;
import static javax.persistence.GenerationType.SEQUENCE;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.SequenceGenerator;
import javax.persistence.Table;
/**
* Districtmaster generated by hbm2java
*/
@SuppressWarnings("serial")
@Entity
@Table(name="districtmaster",schema="aop_gad_v1")
public class Districtmaster implements java.io.Serializable {
private long id;
private Statemaster statemaster;
private String districtName;
private Set<GadGuestHouseMaster> gadGuestHouseMasters = new HashSet<GadGuestHouseMaster>(0);
public Districtmaster() {
}
public Districtmaster(long id) {
this.id = id;
}
public Districtmaster(long id, Statemaster statemaster, String districtName, Set<GadGuestHouseMaster> gadGuestHouseMasters) {
this.id = id;
this.statemaster = statemaster;
this.districtName = districtName;
this.gadGuestHouseMasters = gadGuestHouseMasters;
}
@SequenceGenerator(name="generator_districtmasterid", sequenceName="aop_gad_v1.gad_districtmasterid_seq")
@Id
@GeneratedValue(strategy=SEQUENCE, generator="generator_districtmasterid")
@Column(name="id", unique=true, nullable=false)
public long getId() {
return this.id;
}
public void setId(long id) {
this.id = id;
}
@ManyToOne(fetch=FetchType.LAZY)
@JoinColumn(name="district_of_state")
public Statemaster getStatemaster() {
return this.statemaster;
}
public void setStatemaster(Statemaster statemaster) {
this.statemaster = statemaster;
}
@Column(name="district_name", length=20)
public String getDistrictName() {
return this.districtName;
}
public void setDistrictName(String districtName) {
this.districtName = districtName;
}
@OneToMany(cascade=CascadeType.ALL, fetch=FetchType.LAZY, mappedBy="districtmaster")
public Set<GadGuestHouseMaster> getGadGuestHouseMasters() {
return this.gadGuestHouseMasters;
}
public void setGadGuestHouseMasters(Set<GadGuestHouseMaster> gadGuestHouseMasters) {
this.gadGuestHouseMasters = gadGuestHouseMasters;
}
}
我得到的错误:
[{"timestamp":1512641978311,"status":200,"error":"OK","exception":"org.springframework.http.converter.HttpMessageNotWritableException","message":"可以不写JSON:无限递归(StackOverflowError)；嵌套异常是 com.fasterxml.jackson.databind.JsonMappingException:无限递归(StackOverflowError)(通过引用链:com.gad.rmodels.Statemaster["districtmasters"]->org.hibernate.collection.internal.PersistentSet[0]-
[{"timestamp":1512641978311,"status":200,"error":"OK","exception":"org.springframework.http.converter.HttpMessageNotWritableException","message":"Could not write JSON: Infinite recursion (StackOverflowError); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Infinite recursion (StackOverflowError) (through reference chain: com.gad.rmodels.Statemaster["districtmasters"]->org.hibernate.collection.internal.PersistentSet[0]-
推荐答案
您面临这个问题是因为 Statemaster 模型包含 Districtmaster 模型的对象，而 Districtmaster 模型本身包含 Statemaster 模型的对象.这会导致无限的 json 递归.
You are facing this issue because the Statemaster model contains the object of Districtmaster model, which itself contains the object of Statemaster model. This causes an infinite json recursion.
您可以通过 3 种方法解决此问题.
You can solve this issue by 3 methods.
1 - 创建 DTO 并仅包含您要在响应中显示的字段.
1 - Create a DTO and include only the fields that you want to display in the response.
2 - 您可以使用 @JsonManagedReference 和 @JsonBackReference 批注.
2 - You can use the @JsonManagedReference and @JsonBackReference annotations.
例如将 @JsonManagedReference 注释添加到 Statemaster 模型.
E.g. Add the @JsonManagedReference annotation to the Statemaster model.
@JsonManagedReference
@OneToMany(cascade=CascadeType.ALL, fetch=FetchType.LAZY, mappedBy="statemaster")
public Set<Districtmaster> getDistrictmasters() {
return this.districtmasters;
}
将 @JsonBackReference 注释添加到 Districtmaster 模型.
Add the @JsonBackReference annotation to the Districtmaster model.
@JsonBackReference
@ManyToOne(fetch=FetchType.LAZY)
@JoinColumn(name="district_of_state")
public Statemaster getStatemaster() {
return this.statemaster;
}
3 - 您可以在 getter 或 setter 方法上使用 @JsonIgnore 注释.
3 - You can use the @JsonIgnore annotation on the getter or setter method.
@JsonIgnore
@OneToMany(cascade=CascadeType.ALL, fetch=FetchType.LAZY, mappedBy="statemaster")
public Set<Districtmaster> getDistrictmasters() {
return this.districtmasters;
}
但是，这种方法会从响应中省略 Districtmaster 的集合.
However, this approach will omit the set of Districtmaster from the response.
这篇关于无法写入 JSON:无限递归 (StackOverflowError)；嵌套异常弹簧靴的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
