Write a date as a timestamp in Spring Boot

Question

I have a Spring Boot application where I am using the FasterXML Jackson library for my JSON conversions. But by default, the date is serialized as a timestamp and that is what I want.

MyObj obj = new MyObj();
Date dateUnderTest = new Date();
obj.setLastUpdatedAt(dateUnderTest);
String objStr = objectMapper.writeValueAsString(obj);
JsonNode jsonNode = objectMapper.readTree(objStr);
String readUpdatedAt = jsonNode.findValue("updated_at").asText();
Assert.assertEquals(Long.parseLong(readUpdatedAt), dateUnderTest.getTime());

That test is successful. However, when I try to write obj as my REST API response, I see the date format as:

"updated_at": "2021-04-19T23:33:06.065+0000",

I think Spring Boot is using some other serialization library for this conversion. I want a long timestamp. How can I change that conversion?

Answer 1

Spring's Jackson converter has its own serializer. To set it, we can add this configuration in our application.properties or application.yml file:

spring.jackson.serialization.write_dates_as_timestamps: true