对Spring MVC控制器的POST结果为“ HttpMessageNotReadableException：无法读取JSON：未找到合适的构造函数”

Question

I am using Spring MVC via Spring Boot 1.2.

I have a model that looks like this:

public class Person {
    final private String name;

    /* 
     * Cannot include this constructor because `name` is `final`.
     *
    public Person() {}
     */

    public Person(String name) {
        this.name = name;
    }

    public String getName() {
        return name;
    }
}

And this RestController :

@RestController
public class PeopleController {

    @RequestMapping(value = "/person", method = RequestMethod.POST, consumes = "application/json")
    public Person createPerson(@RequestBody Person person) {
        return person; 
    }
}

I'd like the framework to take the name attribute of the JSON object I POST, and use that to construct my Person instance. But, when I try to POST to this controller like,

$ curl -XPOST -d '{ "name": "Dmitry" }' -H 'Content-Type: application/json' localhost:8080/person

I get this error:

org.springframework.http.converter.HttpMessageNotReadableException: Could not read JSON: No suitable constructor found for type [simple type, class example.Person]: can not instantiate from JSON object (need to add/enable
 type information?)
 at [Source: java.io.PushbackInputStream@4e7fa67d; line: 1, column: 3]; nested exception is com.fasterxml.jackson.databind.JsonMappingException: No suitable constructor found for type [simple type, class example.Person]: 
can not instantiate from JSON object (need to add/enable type information?)
// Trace ommitted

Searching on the Web, people say I need to include an empty constructor. But I can't do that, given the nature of my model, which has final properties that need to be set in the constructor.

So, what are my options for fixing this problem?

Thank you.

Answer 1

Annotate your Person constructor parameter with @JsonProperty .

public Person(@JsonProperty("name") String name) {
    this.name = name;
}