Why jackson formats date to yyyy-MM-dd instead of timestamp? - json

Question

I have my first spring project with a rest service.
Only one problem I cannot solve myself. My "get" request gives the objects date value this way:
{"id":6,"type":"Trainer","changed":"2015-06-20","created":"2015-06-19"}
but I want it in timestamp format, as I thought was the default.
The input dates in my PUT request are parsed from timestamp format as expected.
I am using springframework 4.1.6.RELEASE and fasterxml.jackson 2.5.4
with these spring artifacts: spring-context, spring-webmvc, spring-jdbc
and these fasterxml artifacts: jackson-core, jackson-databind
This is my Controller method:
#Override
#RequestMapping(value="/{id}", method=RequestMethod.GET)
#ResponseBody
public T getObject(#PathVariable("id") long id) {
T obj = dao.getById(id);
logger.debug("GET " + getClass().getSimpleName() + "." + id + ": " + obj);
return obj;
}
My web.xml:
<?xml
version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
version="2.5">
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>
/WEB-INF/spring/root-context.xml
</param-value>
</context-param>
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
<servlet>
<servlet-name>appServlet</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>
/WEB-INF/spring/appServlet/servlet-context.xml
classpath:Beans.xml
</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>appServlet</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>
servlet-context.xml:
<?xml version="1.0" encoding="UTF-8"?>
<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"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
<context:component-scan base-package="de.kreth.clubhelperbackend" />
<mvc:annotation-driven />
<mvc:resources mapping="/resources/**" location="/resources/" />
<bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver" />
<bean
class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="order" value="2" />
<property name="prefix" value="/WEB-INF/views/" />
<property name="suffix" value=".jsp" />
</bean>
</beans>
and my Beans.xml:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop-3.0.xsd">
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"
destroy-method="close">
<property name="driverClassName" value="com.mysql.jdbc.Driver" />
<property name="url" value="jdbc:mysql://localhost/clubhelperbackend" />
<property name="username" value="markus" />
<property name="password" value="0773" />
</bean>
<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
<constructor-arg ref="dataSource" />
</bean>
<bean id="sqlForDialect" class="de.kreth.clubhelperbackend.SqlForMysql">
<constructor-arg ref="jdbcTemplate" />
</bean>
<bean id="personDao" class="de.kreth.clubhelperbackend.dao.PersonDao">
<property name="sqlDialect" ref="sqlForDialect" />
<property name="jdbcTemplate" ref="jdbcTemplate" />
</bean>
<bean id="dbcheckAspect" class="de.kreth.clubhelperbackend.aspects.MysqlDbCheckAspect">
<constructor-arg ref="dataSource" />
</bean>
<!-- <bean id="logger" class="de.kreth.clubhelperbackend.aspects.LoggerAspect" /> -->
<aop:aspectj-autoproxy>
<aop:include name="dbcheckAspect" />
<!-- <aop:include name="logger"/> -->
</aop:aspectj-autoproxy>
</beans>
So, how can I get the json date output in general as a timestamp?
Please note, that I don't want to change the data classes (getters) as they are generated from another project.
--- Edit:
The Person Model:
public class Person implements java.io.Serializable, Data {
private static final long serialVersionUID = -2810735258874241724L;
private Long id;
private String type;
/** Not-null value. */
private java.util.Date changed;
/** Not-null value. */
private java.util.Date created;
public Person() {
}
public Person(Long id) {
this.id = id;
}
public Person(Long id, String type,java.util.Date changed, java.util.Date created) {
this.id = id;
this.type = type;
this.changed = changed;
this.created = created;
}
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
/** Not-null value. */
public java.util.Date getChanged() {
return changed;
}
/** Not-null value; ensure this value is available before it is saved to the database. */
public void setChanged(java.util.Date changed) {
this.changed = changed;
}
/** Not-null value. */
public java.util.Date getCreated() {
return created;
}
#Override
public void setCreated(Date created) {
this.created = created;
}
}
The date interface:
package de.kreth.clubhelperbackend.pojo;
import java.util.Date;
public interface Data {
public Long getId() ;
public void setId(Long id);
public Date getChanged();
public void setChanged(Date changed);
public Date getCreated();
public void setCreated(Date created);
}

Answer 1

According Jackson docs, Jackson should use timestamps in miliseconds by default.
So I see two options. One is that your date format is enforced by #JsonFormat annotation on your date field as #beerbajay mentioned in his comment.
Second option is that somebody configured custom ObjectMapper for your MappingJacksonHttpMessageConverter. Such example configuration is in this SO answer. I would try to find it in your application and talk to the teammate that introduced it why it's needed.
If such custom ObjectMapper isn't configured, it's strange, but at least you can try to explicitly configure SerializationConfig.getDateFormat as WRITE_DATES_AS_TIMESTAMPS to true.

Answer 2

I think Jackson treats java.util.Date and java.sql.Date differently. Even though the later is actually a subclass of the former, Jackson assumes both classes are totally different.
So, if you don't want the value to be converted to 'yyyy-MM-dd', ensure that it is not a java.sql.Date object.
For example:
class Student {
private java.util.Date birthDate;
// getter and setter
}
Student san = new Student();
// Then JSON converted to: 'yyyy-MM-dd' format
san.setBirthDate(new java.sql.Date(System.currentTimeMillis()));
// Then JSON converted to: timestamp format or according to #JsonFormat format
san.setBirthDate(new java.util.Date());