Force Spring Boot Jackson Deserializer to Use BigDecimal: A Practical Guide
Problem: When working with Spring Boot applications, you may encounter scenarios where you need to deserialize JSON data into Java objects that require specific data types, like BigDecimal. By default, Jackson might choose a different type, such as Double, leading to potential precision loss or unexpected behavior.
Rephrasing: Imagine you're building a system that handles financial transactions. You need to store and process monetary amounts with absolute precision, but Jackson might accidentally use a data type that loses decimal places. This could result in incorrect calculations and financial errors.
Scenario: Let's say you have a JSON object representing a product with a price:
{
"name": "Product A",
"price": "12.99"
}
And a corresponding Java class:
public class Product {
private String name;
private BigDecimal price;
// Getters and Setters
}
Without any configuration, Jackson might deserialize the price field as a Double, leading to potential precision loss.
Solution: You can force Jackson to use BigDecimal for deserialization by using annotations or custom deserializers.
Method 1: Using @JsonDeserialize Annotation
Add the @JsonDeserialize(using = BigDecimalDeserializer.class) annotation to the price field:
public class Product {
private String name;
@JsonDeserialize(using = BigDecimalDeserializer.class)
private BigDecimal price;
// Getters and Setters
}
This tells Jackson to use a custom deserializer, BigDecimalDeserializer, which ensures that the JSON string is always converted to a BigDecimal.
Method 2: Creating a Custom Deserializer
You can create a custom deserializer that extends JsonDeserializer<BigDecimal> and overrides the deserialize method.
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.JsonDeserializer;
import java.io.IOException;
import java.math.BigDecimal;
public class BigDecimalDeserializer extends JsonDeserializer<BigDecimal> {
@Override
public BigDecimal deserialize(JsonParser p, DeserializationContext ctxt) throws IOException, JsonProcessingException {
return new BigDecimal(p.getText());
}
}
This deserializer takes the JSON string, parses it as a String, and creates a BigDecimal from it.
Additional Value:
- Performance Consideration: While custom deserializers provide more control, they might have a slight performance impact. Using the
@JsonDeserializeannotation with the built-inBigDecimalDeserializeris generally recommended for simpler scenarios. - Error Handling: You can add error handling within your custom deserializer to gracefully handle invalid input, such as non-numeric strings.
Conclusion:
By applying these techniques, you can ensure that Jackson consistently deserializes JSON data into BigDecimal objects, maintaining precision and avoiding potential data loss. This is particularly crucial in applications that handle financial data, ensuring accuracy and reliability.
References:
