序列化期间的java Jackson异常
我遇到过这个问题,有点接近this issue,但当我完成所有步骤后,我仍然有这样一个例外:
org.codehaus.jackson.map.JsonMappingException: No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationConfig.Feature.FAIL_ON_EMPTY_BEANS) ) (through reference chain: java.util.ArrayList[0]->com.myPackage.SomeEntity["mainEntity"]->com.myPackage.MainEntity["subentity1"]->com.myPackage.Subentity1_$$_javassist_8["handler"])
以下是我的实体代码:
@JsonAutoDetect
public class MainEntity {
private Subentity1 subentity1;
private Subentity2 subentity2;
@JsonProperty
public Subentity1 getSubentity1() {
return subentity1;
}
public void setSubentity1(Subentity1 subentity1) {
this.subentity1 = subentity1;
}
@JsonProperty
public Subentity2 getSubentity2() {
return subentity2;
}
public void setSubentity2(Subentity2 subentity2) {
this.subentity2 = subentity2;
}
}
@Entity
@Table(name = "subentity1")
@JsonAutoDetect
public class Subentity1 {
@Id
@Column(name = "subentity1_id")
@GeneratedValue
private Long id;
@Column(name = "name", length = 100)
private String name;
@JsonIgnore
@OneToMany(mappedBy = "subentity1")
private List<Subentity2> subentities2;
@JsonProperty
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
@JsonProperty
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
//here I didin't add @JsonProperty, cause it leads to cycling during serialization
public List<Subentity2> getSubentity2s() {
return subentity2s;
}
public void setSubentity2s(List<Subentity2> subentity2s) {
this.subentity2s = subentity2s;
}
}
@Entity
@Table(name = "subentity2")
@JsonAutoDetect
public class Subentity2 {
@Id
@Column(name = "subentity2_id")
@GeneratedValue
private Long id;
@Column(name = "name", length = 50)
private String name;
@ManyToOne
@JoinColumn(name = "subentity1_id")
private Subentity1 subentity1;
@JsonProperty
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
@JsonProperty
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@JsonProperty
public Subentity1 getSubentity1() {
return subentity1;
}
public void setSubentity1(Subentity1 subentity1) {
this.subentity1 = subentity1;
}
下面是我转换方法的代码:
private String toJSON(Object model) {
ObjectMapper mapper = new ObjectMapper();
String result = "";
try {
result = mapper.writeValueAsString(model);
} catch (JsonGenerationException e) {
LOG.error(e.getMessage(), e);
} catch (JsonMappingException e) {
LOG.error(e.getMessage(), e);
} catch (IOException e) {
LOG.error(e.getMessage(), e);
}
return result;
}
我将非常感谢任何帮助、建议或代码:)
UPD
alsp,我忘了从我的控制器添加一段代码:
String result = "";
List<SomeEntity> entities = someEntityService.getAll();
Hibernate.initialize(entities);
for (SomeEntity someEntity : entities) {
Hibernate.initialize(someEntity.mainEntity());
Hibernate.initialize(someEntity.mainEntity().subentity1());
Hibernate.initialize(someEntity.mainEntity().subentity2());
}
result = this.toJSON(entities);
我不能忽略任何字段,因为我需要它们
# 1 楼答案
我创建了一个带有平面字段(String、Boolean、Double等)的Bean,这些字段在我的类中,并生成了用于转换的方法
# 2 楼答案
如果您使用的是延迟加载,请添加以下内容
# 3 楼答案
基本上,您的一些字段被打包到懒惰的hibernate代理中。 调用
Hibernate.initialize(model)
在序列化对象之前,它将加载惰性集合和引用但我不会混合使用数据库和视图模型,这是一种糟糕的做法。为restful模型创建一组类,并在序列化之前将数据库实体转换为它们