java - 使用 Jackson 序列化 TreeModel

Question

我有以下模型:

public class CategoryModel {

    public String id;
    public String name;
    public String imageUrl;
    public CategoryModel parent;
    public List<CategoryModel> childrens = new ArrayList<CategoryModel>();
}

我使用 Spring MVc + jackson 返回 Json。

我的操作构建了以下模型，执行后，我收到 stackoverflow 异常。

List<CategoryModel> allCategories = new ArrayList<CategoryModel>(); 

CategoryModel model = new CategoryModel();
model.id = "1";
model.name = "category 1";

CategoryModel model1 = new CategoryModel();
model.id = "2";
model.name = "category 1.1";


model.childrens.add(model1);
model1.parent = model;

allCategories.add(model);

知道我的问题是什么吗？

这是日志文件(部分):

at org.codehaus.jackson.map.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:446) at org.codehaus.jackson.map.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:150) at org.codehaus.jackson.map.ser.BeanSerializer.serialize(BeanSerializer.java:112) at org.codehaus.jackson.map.ser.std.StdContainerSerializers$IndexedListSerializer.serializeContents(StdContainerSerializers.java:122) at org.codehaus.jackson.map.ser.std.StdContainerSerializers$IndexedListSerializer.serializeContents(StdContainerSerializers.java:71) at org.codehaus.jackson.map.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:86) at org.codehaus.jackson.map.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:446) at org.codehaus.jackson.map.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:150) 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) at org.codehaus.jackson.map.ser.BeanSerializer.serialize(BeanSerializer.java:112) at org.codehaus.jackson.map.ser.std.StdContainerSerializers$IndexedListSerializer.serializeContents(StdContainerSerializers.java:122) at org.codehaus.jackson.map.ser.std.StdContainerSerializers$IndexedListSerializer.serializeContents(StdContainerSerializers.java:71) at org.codehaus.jackson.map.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:86) at org.codehaus.jackson.map.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:446) at org.codehaus.jackson.map.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:150) 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) at org.codehaus.jackson.map.ser.BeanSerializer.serialize(BeanSerializer.java:112) at org.codehaus.jackson.map.ser.std.StdContainerSerializers$IndexedListSerializer.serializeContents(StdContainerSerializers.java:122) at org.codehaus.jackson.map.ser.std.StdContainerSerializers$IndexedListSerializer.serializeContents(StdContainerSerializers.java:71) at org.codehaus.jackson.map.ser.std.AsArraySerializerBase.serialize(AsArraySerializerBase.java:86) at org.codehaus.jackson.map.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:446) at org.codehaus.jackson.map.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:150) 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) at org.codehaus.jackson.map.ser.BeanSerializer.serialize(BeanSerializer.java:112) at org.codehaus.jackson.map.ser.std.StdContainerSerializers$IndexedListSerializer.serializeContents(StdContainerSerializers.java:122) at org.codehaus.jackson.map.ser.std.StdContainerSerializers$IndexedListSerializer.serializeContents(StdContainerSerializers.java:71) Caused by: java.lang.StackOverflowError

Answer 1

正如drorb提到的，循环引用是问题所在。但是您应该使用 @JsonBackReference 而不是使用 @JsonIgnore 注释。来指示循环引用。通过此注释，Jackson 能够在反序列化时映射到正确的父级。