After parsing JSON.toJSONString(), "$ref": "$[x].xxx" appears

Reason: When JSON is processing data, the same data appears, and JSON automatically replaces the data of the same node with a reference.

Solution:

String jsonString = JSON.toJSONString(params, SerializerFeature.DisableCircularReferenceDetect);

 SerializerFeature.DisableCircularReferenceDetect: Eliminate the problem of circular references to the same object

Extensions:

 

name	meaning
QuoteFieldNames	Whether to use double quotes when outputting the key, the default is true
UseSingleQuotes	Use single quotes instead of double quotes, defaults to false
WriteMapNullValue	Whether to output fields with null values, the default is false
WriteEnumUsingToString	Enum outputs name() or original, the default is false   1. The current version of fastjon uses the WriteEnumUsingName attribute for enum objects by default, so the enum value will be serialized into its Name. 2. Use the WriteEnumUsingToString method to convert Enum to the return value of toString() during serialization; at the same time, the override toString function can output the enum value in the required form. However, this will cause a problem. The static method valueof of Enum used in the corresponding deserialization may not recognize the self-generated toString(), resulting in deserialization errors. 3. If you want to save the size of the enum after serialization, you can serialize the ordinal value of the enum and save it as an int type. When fastJson is deserializing, if the value is int, it can use ordinal value matching to find the appropriate object. To serialize enum to ordinal, fastjson only needs to disable the WriteEnumUsingName feature. First exclude WriteEnumUsingName based on the default features, and then use the new features for serialization. int features=SerializerFeature.config(JSON.DEFAULT_GENERATE_FEATURE, SerializerFeature.WriteEnumUsingName, false) JSON.toJSONString(obj,features,SerializerFeature.EMPTY);
UseISO8601DateFormat	Date is output in ISO8601 format, the default is false
WriteNullListAsEmpty	If the List field is null, the output is [] instead of null.
WriteNullStringAsEmpty	If the character type field is null, the output is "", not null.
WriteNullNumberAsZero	If the numeric field is null, the output is 0 instead of null.
WriteNullBooleanAsFalse	If the Boolean field is null, the output is false, not null.
SkipTransientField	If it is true, the Field corresponding to the Get method in the class is transient and will be ignored during serialization. Default is true
SortField	Output after sorting by field name. Default is false
WriteTabAsSpecial	Use \t to escape the output, the default is false
PrettyFormat	Whether the result is formatted, the default is false
WriteClassName	Write type information during serialization, default is false. Deserialization is required
DisableCircularReferenceDetect	Eliminate the problem of circular references to the same object. The default is false. When toJSONString is performed, by default, if the object is reused, the object will be referenced by reference.  [         {           "$ref": "$.itemSkuList[0].itemSpecificationList[0]"         },          {           "$ref": "$.itemSkuList[1].itemSpecificationList[0]"         }       ]     Circular references In many scenarios, there are circular references in the objects we need to serialize. In many json libraries, this will lead to stackoverflow. In the powerful fastjson, you don't need to worry about this problem. For example: A a = new A();   B b = new B(a);   a.setB(b);   String text = JSON.toJSONString(a); //{"b":{"a":{"$ref":".."}}}   A a1 = JSON.parseObject(text, A.class);   Assert.assertTrue(a1 == a1.getB().getA());     引用是通过"$ref"来表示的 引用描述 "$ref":".."  上一级 "$ref":"@"   当前对象，也就是自引用 "$ref":"$"   根对象 "$ref":"$.children.0"   基于路径的引用，相当于 root.getChildren().get(0)
WriteSlashAsSpecial	对斜杠’/’进行转义
BrowserCompatible	将中文都会序列化为\uXXXX格式，字节数会多一些，但是能兼容IE 6，默认为false
WriteDateUseDateFormat	全局修改日期格式,默认为false。 JSON.DEFFAULT_DATE_FORMAT = “yyyy-MM-dd”; JSON.toJSONString(obj, SerializerFeature.WriteDateUseDateFormat);
DisableCheckSpecialChar	一个对象的字符串属性中如果有特殊字符如双引号，将会在转成json时带有反斜杠转移符。如果不需要转义，可以使用这个属性。默认为false
NotWriteRootClassName	含义
BeanToArray	将对象转为array输出