org.springframework.web.client.HttpClientErrorException：400使用HttpEntity restTemplate.exchange的错误请求

Question

I am getting HttpClientErrorException: 400 Bad Request when posting some data to client api.

Exception stack trace:

org.springframework.web.client.HttpClientErrorException: 400 Bad Request
org.springframework.web.client.HttpClientErrorException: 400 Bad Request
        at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:91)
        at org.springframework.web.client.RestTemplate.handleResponse(RestTemplate.java:667)
        at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:620)
        at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:580)
        at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:498)

Code

Mode class 1: UserApiResponseBean.java

import java.util.List;

public class UserApiResponseBean {

    private String userCode;

    private String userName;

    private List<Department> DepartmentList;

    public String getUserCode() {
        return userCode;
    }

    public void setUserCode(String userCode) {
        this.userCode = userCode;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public List<Department> getDepartmentList() {
        return DepartmentList;
    }

    public void setDepartmentList(List<Department> departmentList) {
        DepartmentList = departmentList;
    }

}

Model Class 2: Department.java

public class Department {

    private String departmentName;

    private String businessArea;

    public String getDepartmentName() {
        return departmentName;
    }

    public void setDepartmentName(String departmentName) {
        this.departmentName = departmentName;
    }

    public String getBusinessArea() {
        return businessArea;
    }

    public void setBusinessArea(String businessArea) {
        this.businessArea = businessArea;
    }

}

Client Code: Code piece calling client's api

UserApiResponseBean userApiResponseBean = new UserApiResponseBean();
        userApiResponseBean.setUserName("userName1");
        userApiResponseBean.setUserCode("001");

        List<Department> departmentList = new ArrayList<Department>();

        Department departmanetData = new Department();
        departmanetData.setDepartmentName("Department 1");
        departmanetData.setBusinessArea("Business Area 1");

        departmentList.add(departmanetData);

        userApiResponseBean.setDepartmentList(departmentList);

        String userId="userId";
        String password="password";

        String url = "client api url";

        HttpHeaders requestHeader = new HttpHeaders();
        String encoding = Base64.getEncoder().encodeToString((userId + ":" + password).getBytes());
        requestHeader.add(HttpHeaders.AUTHORIZATION, "Basic " + encoding);
        requestHeader.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
        requestHeader.setContentType(MediaType.APPLICATION_JSON);

        HttpEntity<UserApiResponseBean> requestEntity = new HttpEntity<UserApiResponseBean>(userApiResponseBean, requestHeader);

        RestTemplate restTemplate = new RestTemplate();
        restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
        restTemplate.getMessageConverters().add(new StringHttpMessageConverter());

        ResponseEntity<String> responseEntity = restTemplate.exchange(url, HttpMethod.POST, requestEntity, String.class);
        String result = responseEntity.getBody();

Somehow request construction is getting corrupted. Can you please help. I do not have any json/xml related annotations in Model class, also there is no json/spring rest related data in spring-context.xml. Is that the problem ? We are using Spring 4.3.0

Client is expecting a json data, they do not have same UserApiResponseBean.java class on their side.

Answer 1

Just adding the converter name isn't enough. Make sure that Jackson2 is present in your classpath

Jackson 2.x – com.fasterxml.jackson.databind

If using Maven

<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>2.6.3</version>
</dependency>