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This article is about how to solve the problem of jackson serialization and feign return value. The editor thinks it is very practical, so share it with you as a reference and follow the editor to have a look.

Jackson serialization and feign return value jackson note

Serialized / deserialized entity

a. There must be no parameter construction method.

b. Fields should have a set/get method

c. Fields that do not need serialization can be decorated with @ jsonIgnore

FeignClient return value problem

The type of the return value is not necessarily the same as that of the callee.

Such as:

The called party is

ResponseBody@RequestMapping ("test"); public Map test () {Map map = new HashMap (); map.put ("name", "zhangsan"); map.put ("address", "address"); return map;}

Caller:

@ FeignClient ("xxxx") public Interface xxService {@ RequestMapping ("/ test") Test test ();} / * the attribute corresponding to the entity class corresponds to the corresponding attribute in map. * / @ Dataclass Test {public Test () {} private String name; private String address;}

Another way is for the caller to receive it directly with string and then convert it himself.

Feign call exception, deserialization failure exception message is as follows

Nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `xxx` out of START_OBJECT token

Originally, I replaced the original message converter with the fastjson message converter. I thought I didn't replace it, so I tossed around for a while.

Later, when the fastjson message converter was removed, it still reported an error. I thought it should be the data returned.

The data returned by the control layer of the called service is consistent with the object of my deserialization. It should be that the called service uniformly wraps the returned data, resulting in the problem. Just remove the wrapper, or the deserialized object is the wrapped object.

I'm adding the headers attribute to the method mapping, the attribute value Keep-Original=Keep-Original, and removing the wrapper.

@ GetMapping (value = "xxx", headers = {"Keep-Original=Keep-Original"})

Finally, the problem was solved perfectly.

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