Using the JSR 367 – Java API for JSON Binding

Using the JSR 367 – Java API for JSON Binding

 Similar to JAXB for XML processing, the JSR 367: Java API for JSON Binding(JSON-B) defines the binding layer for transforming Java objects to JSON messages and vice-versa, as depicted ahead:

Now let's look at the key components of JSON-B:

Class or Interface	Description
javax.json.bind.Jsonb	This is the core API that provides the functions to serialize a Java object to JSON and deserialize to Java object from a JSON input.
javax.json.bind.JsonbConfig	This class provides functions for formatting and encoding to create customized JSON data.
javax.json.bind.JsonbBuilder	As the name suggests, this API abstracts the creation of JSON-B instances for the specified configuration or provider.
		javax.json.bind.adapter.JsonbAdapter JSON-B supports mapping for a majority of Java data types to JSON. There may be instances when some of the custom Java types may not map to JSON (for example, by default, JSON-B uses ISO date formats required to handle custom date formats. Also, in cases where a client is querying for employee details, we need to respond back with a part of the employee details masking personal details). To handle these situations JsonbAdapter provides the abstraction to implement custom mapping of Java type to JSON and vice-versa. Processing JSON using JSON-B The following example reads the JSON representation of the Employee object from the emp.json file and uses the javax.json.bind.JsonBuilder to create an instance of javax.json.bind.Jsonb to map the Employee object to JSON representation and vice-versa: Read the target JSON document using JsonReader Create an instance of JSON-B using JsonbBuilder Unmarshal the JSON object to the Employee Java object Create a Jsonb instance with formatting enabled Marshal the Employee Java object to JSON The implementation of the preceding steps is demonstrated in the following program: public class JSR367JsonbDefaultBindingExample { private static final Logger logger = Logger.getLogger(JSR367JsonbDefaultBindingExample.class.getName()); public static void main(String[] args) throws IOException { logger.setLevel(Level.INFO); //Step-1:Read the Target JSON Document String jsonFileName = "/emp.json"; InputStream inputStream = JSR374JsonPointerExample.class.getResourceAsStream(jsonFileName); Reader reader = new InputStreamReader(inputStream, "UTF-8"); JsonReader jsonReader = Json.createReader(reader); JsonObject jsonObject = (JsonObject) jsonReader.read(); //Step-2: Create instance of Jsonb using JsonbBuilder Jsonb jsonb = JsonbBuilder.create(); //Step-3:Map JSON to Employee Object Employee employee = jsonb.fromJson(jsonObject.toString(), Employee.class); logger.log(Level.INFO, "Employee Object constructed from JSON:{0}", employee); //Step-4:Create Jsonb instance with formatting enabled JsonbConfig config = new JsonbConfig().withFormatting(Boolean.TRUE); jsonb = JsonbBuilder.create(config); //Step-5:Map Employee Object to JSON String employeeJson = jsonb.toJson(employee); logger.log(Level.INFO, "JSON constructed from Employee object:{0}", employeeJson); } The preceding program reads the emp.json file and prints the Employee object and JSON, as shown ahead: Output of the Program: Employee Object constructed from JSON:Employee{employeeId=100, firstName=John, lastName=Chen, email=john.chen@xxxx.com, hireDate=2008-10-16} JSON constructed from Employee object: { "email": "john.chen@xxxx.com", "employeeId": "100", "firstName": "John", "hireDate": "2008-10-16", "lastName": "Chen" }