Sending a byte array in json using jackson

I want to form a JSON with two fields mimetype and value.The value field should take byte array as its value.

{

  "mimetype":"text/plain",

  "value":"dasdsaAssadsadasd212sadasd"//this value is of type byte[]

}

How can I accomplish this task?

As of now I am using toString() method to convert the byte array into String and form the JSON.