Spring mvc 无法读取HTTP消息：org.springframework.HTTP.converter.httpMessageNodeTableException:缺少必需的请求正文：

我已经创建了一个Rest控制器。我正试图通过Chrome中的POSTMAN访问它。但我得到了这个错误：

警告：无法读取HTTP消息：org.springframework.HTTP.converter.httpMessageNodeTableException:缺少必需的请求正文：public org.springframework.HTTP.ResponseEntity com.ukp.controller.Spring4MVCRestController.createUser（com.ukp.model.User，org.springframework.web.util.UriComponentsBuilder）

我不知道原因是什么。请帮我解决这个问题

    package com.ukp.controller;

    import java.util.List;

    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.http.HttpHeaders;
    import org.springframework.http.HttpStatus;
    import org.springframework.http.MediaType;
    import org.springframework.http.ResponseEntity;
    import org.springframework.web.bind.annotation.PathVariable;
    import org.springframework.web.bind.annotation.RequestBody;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.RestController;
    import org.springframework.web.util.UriComponentsBuilder;

    import com.ukp.model.User;
    import com.ukp.service.UserService;

    @RestController
    public class Spring4MVCRestController {

         @Autowired
            UserService userService;  //Service which will do all data retrieval/manipulation work

        //-------------------Retrieve All Users--------------------------------------------------------

         @RequestMapping(value = "/user/", method = RequestMethod.GET)
            public ResponseEntity<List<User>> listAllUsers() {
                List<User> users = userService.findAllUsers();
                if(users.isEmpty()){
                    return new ResponseEntity<List<User>>(HttpStatus.NO_CONTENT);//You many decide to return HttpStatus.NOT_FOUND
                }
                return new ResponseEntity<List<User>>(users, HttpStatus.OK);
            }

        //-------------------Retrieve Single User--------------------------------------------------------

            @RequestMapping(value = "/user/{id}", method = RequestMethod.GET, produces = MediaType.APPLICATION_JSON_VALUE)
            public ResponseEntity<User> getUser(@PathVariable("id") long id) {
                System.out.println("Fetching User with id " + id);
                User user = userService.findById(id);
                if (user == null) {
                    System.out.println("User with id " + id + " not found");
                    return new ResponseEntity<User>(HttpStatus.NOT_FOUND);
                }
                return new ResponseEntity<User>(user, HttpStatus.OK);
            }

            //-------------------Create a User--------------------------------------------------------


            @RequestMapping(value = "/user/", method = RequestMethod.POST)

            public ResponseEntity<Void> createUser(@RequestBody User user,    UriComponentsBuilder ucBuilder) {
                System.out.println("Creating User " + user.getName());

                if (userService.isUserExist(user)) {
                    System.out.println("A User with name " + user.getName() + " already exist");
                    return new ResponseEntity<Void>(HttpStatus.CONFLICT);
                }

                userService.saveUser(user);

                HttpHeaders headers = new HttpHeaders();
                headers.setLocation(ucBuilder.path("/user/{id}").buildAndExpand(user.getId()).toUri());
                return new ResponseEntity<Void>(headers, HttpStatus.CREATED);
            }

            //------------------- Update a User --------------------------------------------------------

            @RequestMapping(value = "/user/{id}", method = RequestMethod.PUT)
            public ResponseEntity<User> updateUser(@PathVariable("id") long id, @RequestBody User user) {
                System.out.println("Updating User " + id);

                User currentUser = userService.findById(id);

                if (currentUser==null) {
                    System.out.println("User with id " + id + " not found");
                    return new ResponseEntity<User>(HttpStatus.NOT_FOUND);
                }

                currentUser.setName(user.getName());
                currentUser.setAge(user.getAge());
                currentUser.setSalary(user.getSalary());

                userService.updateUser(currentUser);
                return new ResponseEntity<User>(currentUser, HttpStatus.OK);
            }

            //------------------- Delete a User --------------------------------------------------------

            @RequestMapping(value = "/user/{id}", method = RequestMethod.DELETE)
            public ResponseEntity<User> deleteUser(@PathVariable("id") long id) {
                System.out.println("Fetching & Deleting User with id " + id);

                User user = userService.findById(id);
                if (user == null) {
                    System.out.println("Unable to delete. User with id " + id + " not found");
                    return new ResponseEntity<User>(HttpStatus.NOT_FOUND);
                }

                userService.deleteUserById(id);
                return new ResponseEntity<User>(HttpStatus.NO_CONTENT);
            }

          //------------------- Delete All Users --------------------------------------------------------

            @RequestMapping(value = "/user/", method = RequestMethod.DELETE)
            public ResponseEntity<User> deleteAllUsers() {
                System.out.println("Deleting All Users");

                userService.deleteAllUsers();
                return new ResponseEntity<User>(HttpStatus.NO_CONTENT);
            }




    }

这是我的SpringMVC4初始值设定项：

package com.ukp.configuration;

import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

public class SpringMVC4Initializer extends AbstractAnnotationConfigDispatcherServletInitializer {

    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class[] {SpringMVC4Configuration.class};
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {
        return null;
    }

    @Override
    protected String[] getServletMappings() {
        return new String[] { "/" };
    }

}

最后，我的pom.xml：

4.0.0
com.ukp
Spring4MVCrudRestService
0.0.1-快照
战争
带RestFull演示的SpringMVC
4.3.7.1发布
2.5.3
org.springframework
spring上下文
${spring.version}
org.springframework
春豆
${spring.version}
org.springframework
弹簧网
${spring.version}
org.springframework
SpringWebMVC
${spring.version}
org.springframework
德克萨斯州春季
${spring.version}
com.fasterxml.jackson.core
杰克逊数据绑定
${jackson.version}
javax.servlet
javax.servlet-api
3.1.0
org.apache.maven.plugins
maven编译器插件
3.2
1.8
1.8
org.apache.maven.plugins
maven战争插件
2.4
src/main/webapp
Spring4MVCrudRestService
假的
Spring4MVCrudRestService

错误：

INFO:FrameworkServlet“dispatcher”：初始化在381毫秒内完成
2017年4月3日下午4:39:42 org.apache.catalina.core.StandardContext
信息：已完成重新加载名为[/Spring4MVCrudRestService]的上下文
2017年4月3日下午4:41:26 org.springframework.web.servlet.mvc.support.DefaultHandlerExceptionResolver HandleHttpMessageNodeable
警告：无法读取HTTP消息：org.springframework.HTTP.converter.httpMessageNodeTableException:缺少必需的请求正文：public org.springframework.HTTP.ResponseEntity com.ukp.controller.Spring4MVCRestController.createUser（com.ukp.model.User，org.springframework.web.util.UriComponentsBuilder）
2017年4月3日下午4:41:40 org.springframework.web.servlet.PageNotFound handleHttpRequestMethodNotSupported

我正在尝试通过邮递员访问POST请求：

http://localhost:8282/Spring4MVCCRUDRestService/user/

这真的是演示问题的最小完整程序吗？如果你能把这个问题简化为一个小问题，你就更有可能得到高质量的答案。这真的是证明问题的最小完整程序吗？如果你能将其降低到最低限度，你就更有可能得到高质量的答案。

package com.ukp.service;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.concurrent.atomic.AtomicLong;

import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import com.ukp.model.User;

@Service
@Transactional
public class UserServiceImpl implements UserService {

    private static final AtomicLong counter = new AtomicLong();

    private static List<User> users;

    static{
        users= populateDummyUsers();
    }

    public List<User> findAllUsers() {
        return users;
    }


    @Override
    public User findById(long id) {
         for(User user : users){
                if(user.getId() == id){
                    return user;
                }
            }
            return null;
    }

    @Override
    public User findByName(String name) {
        for(User user : users){
            if(user.getName().equalsIgnoreCase(name)){
                return user;
            }
        }
        return null;
    }

    @Override
    public void saveUser(User user) {
         user.setId(counter.incrementAndGet());
            users.add(user);

    }

    @Override
    public void updateUser(User user) {
        int index = users.indexOf(user);
        users.set(index, user);

    }

    @Override
    public void deleteUserById(long id) {
         for (Iterator<User> iterator = users.iterator(); iterator.hasNext(); ) {
                User user = iterator.next();
                if (user.getId() == id) {
                    iterator.remove();
                }
            }

    }


    public static List<User> populateDummyUsers() {
        List<User> users = new ArrayList<User>();
        users.add(new User(counter.incrementAndGet(),"Sam",30, 70000));
        users.add(new User(counter.incrementAndGet(),"Tom",40, 50000));
        users.add(new User(counter.incrementAndGet(),"Jerome",45, 30000));
        users.add(new User(counter.incrementAndGet(),"Silvia",50, 40000));
        return users;
    }

    @Override
    public void deleteAllUsers() {
        users.clear();

    }

    @Override
    public boolean isUserExist(User user) {
         return findByName(user.getName())!=null;
    }

}

package com.ukp.model;

public class User {

    private long id;
    private String name;
    private int age;
    private double salary;

    public User() {
        id = 0;
    }

    public User(long id, String name, int age, double salary) {
        this.id = id;
        this.name = name;
        this.age = age;
        this.salary = salary;
    }

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public double getSalary() {
        return salary;
    }

    public void setSalary(double salary) {
        this.salary = salary;
    }

     @Override
        public int hashCode() {
            final int prime = 31;
            int result = 1;
            result = prime * result + (int) (id ^ (id >>> 32));
            return result;
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj)
                return true;
            if (obj == null)
                return false;
            if (getClass() != obj.getClass())
                return false;
            User other = (User) obj;
            if (id != other.id)
                return false;
            return true;
        }

        @Override
        public String toString() {
            return "User [id=" + id + ", name=" + name + ", age=" + age
                    + ", salary=" + salary + "]";
        }

}

package com.ukp.configuration;

import org.springframework.web.servlet.support.AbstractAnnotationConfigDispatcherServletInitializer;

public class SpringMVC4Initializer extends AbstractAnnotationConfigDispatcherServletInitializer {

    @Override
    protected Class<?>[] getRootConfigClasses() {
        return new Class[] {SpringMVC4Configuration.class};
    }

    @Override
    protected Class<?>[] getServletConfigClasses() {
        return null;
    }

    @Override
    protected String[] getServletMappings() {
        return new String[] { "/" };
    }

}

package com.ukp.configuration;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.EnableWebMvc;

@Configuration
@EnableWebMvc
@ComponentScan(basePackages="com.ukp")
public class SpringMVC4Configuration {

}