How to Use Spring Boot's 'spring.jackson.date-format' Property?

Question

According to the Current SpringBoot Reference Guide if I set the spring.jackson.date-format property, it will: Date format string or a fully-qualified date format class name. For instance 'yyyy-MM-dd HH:mm:ss'.

However, it doesn't work this way with Spring Boot 1.5.3.

To demonstrate, starting with this class:

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

import java.time.Instant;

@SpringBootApplication
public class DemoApplication {
  public static void main(String[] args) {
    SpringApplication.run(DemoApplication.class, args);
  }
}

@RestController
class NowController{

  @GetMapping("/now")
  Instant getNow(){
    return Instant.now();
  }

}

and this src/main/resources/application.properties

spring.jackson.date-format=dd.MM.yyyy

and this build.gradle:

buildscript {
    ext {
        springBootVersion = '1.5.3.RELEASE'
    }
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
    }
}

apply plugin: 'org.springframework.boot'

version = '0.0.1-SNAPSHOT'
sourceCompatibility = 1.8

repositories {
    mavenCentral()
}

dependencies {
    compile('org.springframework.boot:spring-boot-starter-web')
    compile('com.fasterxml.jackson.datatype:jackson-datatype-jdk8')
    compile('com.fasterxml.jackson.datatype:jackson-datatype-jsr310')
    testCompile('org.springframework.boot:spring-boot-starter-test')
}

I get the following:

http localhost:8080/now
HTTP/1.1 200 
Content-Type: application/json;charset=UTF-8
Date: Tue, 25 Apr 2017 22:37:58 GMT
Transfer-Encoding: chunked

"2017-04-25T22:37:58.319Z"

Notice that this is not the specified format dd.MM.yyyy. Is there something else required is spring.jackson.date-format not working as documented?

Answer 1

That property is only used for the java.util.Date serialization and not java.time.* classes.

You can have on demand (per field) format specified with @JsonFormat(pattern="dd.MM.yyyy")

or

Create a bean that implements the org.springframework.boot.autoconfigure.jackson.Jackson2ObjectMapperBuilderCustomizer interface and setup custom serializers on the ObjectMapper for java.time.* classes that use a more sensible format.