将java.util.Date转换为json格式

Question

I have to convert my POJO to JSON string in order to send to client code.

When I do this however, java.util.Date field (having value " 2107-06-05 00:00:00.0 ") from within my POJO gets translated as " 1496592000000 " which I think is a time since epoch. I want it to be something more readable in Json may be in 'DD/MM/YYYY' format.

I am using RestEasy controller in Spring Boot application which handles the conversion for the Java object to JSON.

Any clues what is going wrong?

Answer 1

RestEasy supports JSON via Jackson, so you can handle Date serialization in several ways.

1. @JsonFormat annotation

If you want to format specific field - simply add @JsonFormat annotation to your POJO.

public class TestPojo {

    @JsonFormat(shape = JsonFormat.Shape.STRING, pattern = "dd-MM-yyyy")
    public Date testDate;
}

2. Jackson properties

If you want to set Date serialization format globally - you have to tune Jackson configuration properties. Eg for application.properties file format.

First one disables WRITE_DATES_AS_TIMESTAMPS serialization feature :

spring.jackson.serialization.write-dates-as-timestamps=false

Second one defines date format:

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

Or, for application.yml file format:

spring:
  jackson:
    date-format: "dd-MM-yyyy"
    serialization:
      write_dates_as_timestamps: false

3. Custom Serializer

If you want to take full control over serialization - you have to implement a custom StdSerializer .

public class CustomDateSerializer extends StdSerializer<Date> {

    private SimpleDateFormat formatter = new SimpleDateFormat("dd-MM-yyyy");

    public CustomDateSerializer() {
        this(null);
    }

    public CustomDateSerializer(Class t) {
        super(t);
    }

    @Override
    public void serialize(Date date, JsonGenerator generator, SerializerProvider provider) 
        throws IOException, JsonProcessingException {

        generator.writeString(formatter.format(date));
    }
}

And then use it with @JsonSerialize :

public class TestPojo {

    @JsonSerialize(using = CustomDateSerializer.class)
    public Date testDate;
}