Json（fasterxml）stackoverflow异常 [英] Json (fasterxml) stackoverflow exception
问题描述
尝试序列化类别时，我会得到一个堆栈溢出。
When trying to serialize a Category I get a stackoverflow.
例外
警告：StandardWrapperValve [dispatcher]：
Servlet调度程序的Servlet.service（）在
抛出异常java.lang.StackOverflowError java.lang.ClassLoader.defineClass1（本机方法） ）
java.lang.ClassLoader.defineClass（ClassLoader.java:760）at
org.apache.felix.framework.BundleWiringImpl $ BundleClassLoader.findClass（BundleWiringImpl.java:2279）
at
org.apache.felix.framework.BundleWiringImpl.findClassOrResourceByDelegation（BundleWiringImpl.java:1501）
at
org.apache.felix.framework.BundleWiringImpl.access $ 400（BundleWiringImpl.java:75）
at
org.apache.felix.framework.BundleWiringImpl $ BundleClassLoader.loadClass（BundleWiringImpl.java:1955）
at java.lang.ClassLoader.loadClass（ClassLoader.java:357）at
com.fasterxml.jackson.databind.ser.std.BeanSerialize rBase.serializeFields（BeanSerializerBase.java:660）
at
com.fasterxml.jackson.databind.ser.BeanSerializer.serialize（BeanSerializer.java:152）
at
com。 fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents（IndexedListSerializer.java:100）
at
com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents（IndexedListSerializer.java:21 ）
at
com.fasterxml.jackson.databind.ser.std.AsArraySerializerBase.serialize（AsArraySerializerBase.java:183）
at
com.fasterxml.jackson.databind.ser .BeanPropertyWriter.serializeAsField（BeanPropertyWriter.java:541）
at
com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields（BeanSerializerBase.java:644)
at
com.fasterxml.jackson.databind.ser.BeanSerializer.serialize（BeanSerializer.java:152）
Warning: StandardWrapperValve[dispatcher]: Servlet.service() for servlet dispatcher threw exception java.lang.StackOverflowError at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:760) at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.findClass(BundleWiringImpl.java:2279) at org.apache.felix.framework.BundleWiringImpl.findClassOrResourceByDelegation(BundleWiringImpl.java:1501) at org.apache.felix.framework.BundleWiringImpl.access$400(BundleWiringImpl.java:75) at org.apache.felix.framework.BundleWiringImpl$BundleClassLoader.loadClass(BundleWiringImpl.java:1955) at java.lang.ClassLoader.loadClass(ClassLoader.java:357) at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:660) at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152) at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:100) at com.fasterxml.jackson.databind.ser.impl.IndexedListSerializer.serializeContents(IndexedListSerializer.java:21) at com.fasterxml.jackson.databind.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:183) at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:541) at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:644) at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:152)
Category.java
@Entity
public class Category implements DataObject, Serializable {
@Id
@GeneratedValue
private Long id;
private String title;
private String description;
@ManyToOne @JsonIgnore
private Category parent;
@Override
public long getId() {
return id;
}
@Override
public void setId(long id) {
this.id = id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public Category getParent() {
return null;//return parent;
}
public void setParent(Category parent) {
// this.parent = parent;
}
public boolean isMainCategory()
{
return true;// return this.parent == null;
}
/**
* Returns the chain of parent categories with the main category on index 0
* @return Chain of categories
*/
public List<Category> getParentChain()
{
List<Category> cats = new ArrayList<>();
Category current = this;
while(!current.isMainCategory())
{
cats.add(current);
current = current.getParent();
}
cats.add(current);
Collections.reverse(cats);
return cats;
}
@Override
public String toString()
{
return this.title;
}
@Override
public boolean equals(Object o)
{
if(!(o instanceof Category))return false;
Category c = (Category)o;
return c.title.equals(this.title);
}
@Override
public int hashCode()
{
return super.hashCode();
}
}
休息控制器功能
@RequestMapping(value="/{id}", method=RequestMethod.GET)
public ResponseEntity<Category> get(@PathVariable("id") long categoryId)
{
Category c = service.getCategoryRepository().ReadValue(categoryId);
if(c == null)
return new ResponseEntity<>(HttpStatus.NOT_FOUND);
return new ResponseEntity<>(c,HttpStatus.OK);
}
注意
即使我更换返回新的ResponseEntity<>（c，HttpStatus.OK）; 并带有返回新的ResponseEntity<> ;（new Category（），HttpStatus.OK）; 我将得到一个stackoverflow whilist，这些字段都没有包含值。
Even when I replace return new ResponseEntity<>(c,HttpStatus.OK); with return new ResponseEntity<>(new Category(),HttpStatus.OK); I will get a stackoverflow whilist none of the fields contain a value.
它的工作原理和我的其他类一样好，只有这个类导致堆栈溢出。
It works fine with my other classes it's only this class that causes a stackoverflow.
推荐答案
如果你发表评论 private类别父级; 您将没有StackOverflow。我在具有循环依赖项的项目中遇到了同样的问题。
Probably if you comment private Category parent; you will not have the StackOverflow. I've got the same problem in a project with circular dependencies.
解决此问题的最佳方法是使用父代码而不是类代码：
The best way to solve this problem is to use the id of the parent instead of the Class like:
private Long parentId;
编辑：
问题在于尝试序列化的 getParentChain（）。通过在方法之前添加@JsonIgnore来解决问题。
The problem is with getParentChain() that is trying to be serialized. By adding @JsonIgnore before the method the problem was resolved.
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