Data type conversion example for Portal for Java with Jackson

Handler.java

public abstract class Handler<T> implements Action<Map<String, Object>> {
  
    private final Class<T> desiredType;

    @SuppressWarnings("unchecked")
    public Handler() {
        // Each casting is not safe. Improve if you want to use in production
        // See org.springframework.core.GenericTypeResolver.resolveTypeArgument
        ParameterizedType pt = (ParameterizedType) this.getClass().getGenericSuperclass();
        desiredType = (Class<T>) pt.getActualTypeArguments()[0];
    }

    @Override
    public void on(Map<String, Object> map) {
        // The convertValue will convert map to JSON and JSON to desired type of object
        // Reflection lib like Apache Commons BeanUtils may be better in performance
        handle(new ObjectMapper().convertValue(map, desiredType));
    }

    public abstract void handle(T t);
    
}

Somewhere.java

socket.on(new Handler<Book>() {
    @Override
    public void handle(Book book) {
        // Your logic here
    }
});