How to Use Custom Serializer With Jackson in Java

1. Serialization in Java
2. Custom Serializer With Jackson on the Class
3. Use the serialize() Method in Java

This tutorial will look at how to utilize a custom Serializer with Jackson in Java. First, let’s have a look at the serialization concept.

Serialization in Java

The serialization process in Java is a technique to convert an object to and from a stream of bytes. This not only makes it possible to store an object in a file, but it also makes it possible to send an object over a network.

The serialization process begins with creating an implementation of the Serializable interface, followed by the use of Java.io.

Custom Serializer With Jackson on the Class

Let’s create two simple classes, ’ CustomerandProduct`.

Code - Customer class:

public class Customer {
  public int id;
  public String Cname;
}

Code - Produtc class:

public class Product {
  public int id;
  public String Productname;
  public Customer buyer;
}

Apply JsonSerialize in the Class

Now, We’ll register the serializer in the class like in the following.

@JsonSerialize(using = ProductSerializer.class)
public class Product {
  public int id;
  public String Productname;
  public Customer buyer;
}

Then apply standard serialization.

Product p = new Product(10, "drinks", new Customer(12, "Peter"));
String serialized = new ObjectMapper().writeValueAsString(p);

Lastly, We will obtain the individualized JSON output generated by the serializer and defined using the @JsonSerialize.

Use the serialize() Method in Java

We can use the StdSerializer class to implement a custom serializer. In this case, we will need to override the serialize() method.

Syntax:

public abstract void serialize(Product val, JsonGenerator jg, SerializerProvider p)
    throws IOException

If you don’t mind having a custom serializer, you don’t need to develop one for the Product class. Instead, you should write one for the Customer class.

public void serialize(Product value, JsonGenerator jg, SerializerProvider p)
    throws IOException, JsonProcessingException {
  jg.writeNumber(id);
}