Form not posting data to Spring Controller

I am really new to Spring and tring to learn through some tutorials on the net. I created a simple Spring MVC Login App using AngularJS as the frontend and using JSON to post data to Spring Controller.

My simple login form:

<form id="loginForm" ng-submit="login()" novalidate ng-controller="loginController" align="center">
            <fieldset>
                <div class="form-group col-lg-10">
                    <label for="username" class="control-label">Username</label>
                    <input class="form-control" ng-model="username" placeholder="Username" type="text">
                </div>
                <div class="form-group col-lg-10">
                    <label for="password" class="control-label">Password</label>
                    <input class="form-control" ng-model="password" placeholder="Password" type="password">
                </div>
                <div class="form-group">
                    <div class="col-lg-10 col-lg-offset-25">
                        <button type="submit" class="btn btn-primary">Login</button>
                        <button type="reset" class="btn btn-default">Reset</button>
                    </div>
                </div>
            </fieldset>
        </form>

My angular controller:

function loginController($scope){
    $scope.login=function(){
        var data=$scope.fields;
        var response = $http.post("rest/dologin",data);
        alert(response);

    };
};

My Web.xml:

<welcome-file-list>
        <welcome-file>pages/login.html</welcome-file>
    </welcome-file-list>

    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>
        /WEB-INF/spring-core.xml
    </param-value>
    </context-param>

    <!-- Spring MVC -->
    <servlet>
        <servlet-name>spring-mvc</servlet-name>
        <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
        <init-param>
            <param-name>contextConfigLocation</param-name>
            <param-value>
                /WEB-INF/spring-mvc.xml
            </param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>spring-mvc</servlet-name>
        <url-pattern>/rest/*</url-pattern>
    </servlet-mapping>

My Spring Controller:

@Controller
public class LoginController {




@RequestMapping(value = "/dologin", method = RequestMethod.POST, headers = {"Content-type=application/json"})
protected @ResponseBody String validateUser(@RequestBody User user) {

    System.out.println(user.getUsername() + " " + user.getPassword());
    return "Sucess" + " " + user.getUsername();

    }
}

My Dispatcher Servlet:

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xsi:schemaLocation="http://www.springframework.org/schema/beans 
     http://www.springframework.org/schema/beans/spring-beans-4.1.xsd  
     http://www.springframework.org/schema/context 
     http://www.springframework.org/schema/context/spring-context-4.1.xsd
     http://www.springframework.org/schema/mvc
     http://www.springframework.org/schema/mvc/spring-mvc.xsd"     
    xmlns:context="http://www.springframework.org/schema/context">

    <context:component-scan base-package="com.app.web.controllers" />
    <mvc:annotation-driven />
</beans> 

I tried putting an alert box in the Angularjs controller and it displays but the print statement in my Spring Controller doesn't print. Also, there are no errors displayed.

Update:

I tried posting data to my Spring controller and it gives correct response. So, problem is with the AngularJS Controller. I tried using firebug and see that the login method in angular controller is not called but the script itself is loaded.

Update2:

I changed my AngularJS controller to this and now the controller is getting detected:

var loginApp = angular.module('loginApp',[]);
loginApp.controller('loginController', ['$scope','$http',function($scope,$http) {

  $scope.login = function() {
          var data=$scope.fields;
          var response = $http.post('/test/rest/dologin',data).success(function(data){
            alert(response);
          });
      }

This time I get a "Error 400 Bad request" error code in Firebug:

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"/>
<title>Error 400 BAD_REQUEST</title>
</head>
<body><h2>HTTP ERROR 400</h2>
<p>Problem accessing /test/rest/dologin. Reason:
<pre>    BAD_REQUEST</pre></p><hr /><i><small>Powered by Jetty://</small></i><br/>                  

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</body>
</html>
  };
}]);

The server is giving following exception:

NotReadableException: Required request body is missing

Please suggest what I am doing wrong here.