如何将具有Date类型字段的JSON反序列化为POJO。

Question

I'm working on a REST api using Jersey+Jackson.

I want to convert JSON --> POJO.

My Pojo class is having a Date field called 'created' .

In a String 'jsonUser' i have json representation of my Pojo .

Now when i use following code to convert JSON representation to Pojo object :

ObjectMapper mapper = new ObjectMapper();       
Pojo oldUser = mapper.readValue(jsonUser, Pojo.class);

I get following error :

Exception: Can not construct instance of java.sql.Timestamp from String value '2013-07-29 11:41:00.0': not a valid representation 

Jackson is not able to deserialize String representation to Date object.

How can i configure Jackson to do that?

Answer 1

Problem might be in date conversion. Just do it in following way:

public class Pojo
{
private String created;
private Date createdDate;

//getter methods. 

//setter methods
public void setCreated(String created)
{
  this.created = created;
  //Logic for converting MySQL-String representation to desired
}

//mapper config
ObjectMapper mapper = new ObjectMapper();
mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
mapper.setSerializationInclusion(Include.NON_NULL);
mapper.setSerializationInclusion(Include.NON_EMPTY);
mapper.configure(Feature.ALLOW_UNQUOTED_CONTROL_CHARS, true );
}

Pojo oldUser = mapper.readValue(jsonUser, Pojo.class);

• Create a mapper which can avoid exception if values are not present.
• Create POJO with created as String field and createdDate with Date field.
• In setter for 'created', write logic for conversion of String to Date .
• JSON will assign String to POJO properly by calling setter method on created .
• In setter, the string-date conversion logic will take care of createdDate field.

Hope it helps.

Answer 2

Just store it as long. To get the long value use dateObj.getTime(); To create a date object from long use new Date(longVal)