无法编写JSON:无限递归(StackOverflowError);嵌套异常Spring Boot [英] Could not write JSON: Infinite recursion (StackOverflowError); nested exception spring boot
问题描述
这是我的区控制器，当我尝试在保存后获取数据时，我得到了错误，即使当我尝试获取对象形式getDistrict(Long id)时，同样的警告也请提出一些建议，在春季环境中是非常新的:
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;
}
}
地区模型:
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);嵌套的 例外是com.fasterxml.jackson.databind.JsonMappingException: 无限递归(StackOverflowError)(通过参考链: 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
您正面临此问题，因为Statemaster模型包含Districtmaster模型的对象，而Districtmaster模型本身也包含Statemaster模型的对象.这将导致无限的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-创建一个DTO，并仅包含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-可以使用@JsonManagedReference和@JsonBackReference批注.
2 - You can use the @JsonManagedReference and @JsonBackReference annotations.
例如将@JsonManagedReference批注添加到Statemaster模型中.
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模型中.
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批注.
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区域管理员的集合.
However, this approach will omit the set of Districtmaster from the response.
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