See the below steps to create sample application using JQuery, Spring MVC @RequestBody and JSON :

1- Define dependency for Spring, JSON in pom.xml as below:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 <modelVersion>4.0.0</modelVersion>
 <groupId>Demo</groupId>
 <artifactId>Demo</artifactId>
 <packaging>war</packaging>
 <version>1.0</version>
 <name>Demo</name>
 <description></description>
 <build>
  <plugins>
   <plugin>
    <artifactId>maven-compiler-plugin</artifactId>
    <configuration>
     <source>1.5</source>
     <target>1.5</target>
    </configuration>
   </plugin>
   <plugin>
    <artifactId>maven-war-plugin</artifactId>
    <version>2.0</version>
    <configuration>
     <webResources>
      <resource>
       <directory>WebContent</directory>
      </resource>
     </webResources>
    </configuration>
   </plugin>
  </plugins>
 </build>

 <properties>
  <spring.version>3.0.5.RELEASE</spring.version>
 </properties>

 <dependencies>
  <dependency>
   <groupId>org.codehaus.jackson</groupId>
   <artifactId>jackson-mapper-asl</artifactId>
   <version>1.7.1</version>
  </dependency>
  <dependency>
   <groupId>javax.servlet</groupId>
   <artifactId>servlet-api</artifactId>
   <version>2.5</version>
  </dependency>
  <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-core</artifactId>
   <version>${spring.version}</version>
  </dependency>

  <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-web</artifactId>
   <version>${spring.version}</version>
  </dependency>

  <dependency>
   <groupId>org.springframework</groupId>
   <artifactId>spring-webmvc</artifactId>
   <version>${spring.version}</version>
  </dependency>
 </dependencies>
</project>

2- Now define the model class for binding data as below:

User.java

package com.evon.model.user;

import java.io.Serializable;

import org.codehaus.jackson.annotate.JsonIgnoreProperties;
import org.codehaus.jackson.annotate.JsonProperty;
import org.codehaus.jackson.map.annotate.JsonSerialize;

@JsonIgnoreProperties(ignoreUnknown = true)
@JsonSerialize(include = JsonSerialize.Inclusion.NON_DEFAULT)
public class UserModel implements Serializable {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    @JsonProperty
    private Integer userId; 
    @JsonProperty
        private String emailId;
    @JsonProperty
        private String password;


    public Integer getUserId() {
        return userId;
    }
    public void setUserId(Integer userId) {
        this.userId = userId;
    }
    public String getEmailId() {
        return emailId;
    }
    public void setEmailId(String emailId) {
        this.emailId = emailId;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
}

3- Define response class as below:

UserResponse.class

package com.evon.model.response;

import java.io.Serializable;

import org.codehaus.jackson.annotate.JsonIgnoreProperties;
import org.codehaus.jackson.annotate.JsonProperty;
import org.codehaus.jackson.map.annotate.JsonSerialize;

@JsonIgnoreProperties(ignoreUnknown = true)
@JsonSerialize(include = JsonSerialize.Inclusion.NON_DEFAULT)
public class UserResponse implements Serializable{

    /**
     * 
     */
    private static final long serialVersionUID = 1L;
    @JsonProperty
    private String status ;
    @JsonProperty
    private String error ;  
    @JsonProperty
    private String message;

    private String errorType;

    private Boolean success;

    public String getStatus() {
        return status;
    }
    public void setStatus(String status) {
        this.status = status;
    }
    public String getError() {
        return error;
    }
    public void setError(String error) {
        this.error = error;
    }
    /**
     * @param errorType the errorType to set
     */
    public void setErrorType(String errorType) {
        this.errorType = errorType;
    }
    /**
     * @return the errorType
     */
    public String getErrorType() {
        return errorType;
    }
    /**
     * @return the message
     */
    public String getMessage() {
        return message;
    }
    /**
     * @param message the message to set
     */
    public void setMessage(String message) {
        this.message = message;
    }


    public Boolean getSuccess() {
        return success;
    }

    public void setSuccess(Boolean success) {
        this.success = success;
    }

}

4- Now define registerUser function in your controller as below:

LoginController.java

import com.evon.controller;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;

import com.flippadoo.model.response.UserResponse;
import com.flippadoo.model.user.UserModel;


@Controller
public class LoginController {

 @RequestMapping(value = "/addPerson",
                method = RequestMethod.POST,
                headers = {"Content-type=application/json"})
 @ResponseBody
 Public UserResponse registerUser(HttpServletRequest request, HttpServletResponse response)
   throws Exception {

  UserResponse response = new UserResponse();
  response.setStatus("Ok");
  response.setMessage("User created successfully");
  return response;
 }
}

5- Define the below configuration in you servlet.xml file as below:

demo-servlet.xml

<beans xmlns="http://www.springframework.org/schema/beans"
 xmlns:context="http://www.springframework.org/schema/context"
 xmlns:mvc="http://www.springframework.org/schema/mvc" 
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="
        http://www.springframework.org/schema/beans     
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context 
        http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">

 <context:component-scan base-package="com.evon.controller" />
 <mvc:annotation-driven />
</beans>

6- web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app id="WebApp_ID" version="2.4"
 xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
 <display-name>SpringExamples</display-name>
 <welcome-file-list>
  <welcome-file>index.jsp</welcome-file>
 </welcome-file-list>

 <servlet>
  <servlet-name>dispatcherServlet</servlet-name>
  <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
  <load-on-startup>1</load-on-startup>
 </servlet>
 <servlet-mapping>
  <servlet-name>dispatcherServlet</servlet-name>
  <url-pattern>/</url-pattern>
 </servlet-mapping>
</web-app>

7- Now define jsp page as below:

createUser.jsp

<!DOCTYPE html>
<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<%@taglib uri="http://www.springframework.org/tags" prefix="spring"%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Registration Form</title>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.6.1/jquery.min.js"></script>
<script type="text/javascript">

//Ajax submit create user
function ajaxSubmitCreateUserForm()
{

     $('#createUser').ajaxForm({
            url: 'registerUser',
              type: "POST",
              data: JSON.stringify({ firstName: "Akash", lastName: "Singh", emailId: "akash@gmail.com" }),
              contentType: 'application/json',
       success: function(response) {

           if(response.status == 'OK')
              {
                   alert("User/Developer is created");
              }
           else
              {
               alert("FAILED, Try again ...");
              }

       },
            error : function() { alert('System error occured, please try again ...'); }

   });


     $('#createUser').submit();

}

</script>
</head>

<body>
<div class="wrapper">
    <div class="formContainer">
        <form:form name="createUser" id="createUser" method="post" onsubmit="return false;">
            <h2>User Create Form</h2>
            <dl>
                <dt>
                    Email 
                </dt>
                <dd>
                    <input type="text" name="emailId" id="emailId" required="required">
                    <span class="separate">Please provide valid Email id</span>
                </dd>

                 <dt>
                    First Name 
                </dt>
                <dd>
                    <input type="text" name="firstName" id="firstName" required="required">

                </dd>

                 <dt>
                    Last Name 
                </dt>
                <dd>
                    <input type="text" name="lastName" id="lastName" required="required">

                </dd>
            </dl>
            <div class="buttonBlock">
                <button class="submitBTN" onclick="ajaxSubmitCreateUserForm();">Submit</button>
            </div>
        </form:form>
    </div>
</div>
</body>
</html>

Hope this will help you :)