Posting JSON to Spring MVC Controller

Spring MVC can be setup to automatically bind incoming JSON string into a Java object. Firstly, ensure you have jackson-mapper-asl included on the classpath:

<dependency>
  <groupId>org.codehaus.jackson</groupId>
  <artifactId>jackson-mapper-asl</artifactId>
  <version>1.9.13</version>
</dependency>

Assuming the JSON string we want to bind represent a person object like this:

{
  name: "Gerry",
  age: 20,
  city: "Sydney"
}

Which will be bound into following Java class:

public class Person {
  private String name;
  private int age;
  private String city;
  // getters & setters ...
}

Declare the Spring MVC controller handler method like below. The handler method is mapped into path “addPerson” with method POST.

@RequestMapping(value = "/addPerson",
                method = RequestMethod.POST,
                headers = {"Content-type=application/json"})
@ResponseBody
public JsonResponse addPerson(@RequestBody Person person) {
  logger.debug(person.toString());
  return new JsonResponse("OK","");
}

Also pay attention to @ResponseBody and the returned JsonResponse object. Here JsonResponse is a class to return the result of the addPerson operation.

public class JsonResponse {

  private String status = "";
  private String errorMessage = "";

  public JsonResponse(String status, String errorMessage) {
    this.status = status;
    this.errorMessage = errorMessage;
  }
}

When converted to JSON this will look like this:

{
  status : "OK",
  errorMessage : ""
}

Below is an example jQuery based javascript handler that posts into the above Spring MVC handler and observe the returned value:

$.ajax({
  type: "POST",
  url: "addPerson",
  data: JSON.stringify({ name: "Gerry", age: 20, city: "Sydney" }),
  contentType: 'application/json',
  success: function(data) {
    if(data.status == 'OK') alert('Person has been added');
    else alert('Failed adding person: ' + data.status + ', ' + data.errorMessage);
  }
});