JSON-P JsonObjectBuilder Java Example

JSR 354 addresses the standard Java API for JSON processing(JSON-P) and shipped as part of JavaEE 7. The Java API for JSON Processing provides portable APIs to parse, generate, transform, and query JSON using the streaming API or the object model API.

JSON-P Object model API provides below important classes and interfaces:

• Json - Contains static methods to create JSON parsers, generators, and their factories.
• JsonObjectBuilder - Creates an object model in memory by adding values from application code.
• JsonArrayBuilder - Creates an array model in memory by adding values from application code.
• JsonReader - Reads a JsonObject or a JsonArray from an input source.
• JsonWriter - Writes a JsonObject or a JsonArray to an output source.

In this example, we use a JsonObjectBuilder to create a JSON string.

Add Dependencies

JSON-P is the reference implementation for Java JSON Processing API. We can use this in maven project by adding the following dependencies:

<dependency>
    <groupId>javax.json</groupId>
    <artifactId>javax.json-api</artifactId>
    <version>1.1</version>
</dependency>

<dependency>
    <groupId>org.glassfish</groupId>
    <artifactId>javax.json</artifactId>
    <version>1.1</version>
</dependency>

Java JSON-P JsonObjectBuilder Example

package net.javaguides.jsonp.examples;

import java.io.StringWriter;
import java.time.LocalDate;
import java.util.HashMap;
import java.util.Map;

import javax.json.Json;
import javax.json.JsonObject;
import javax.json.JsonObjectBuilder;
import javax.json.JsonWriter;
import javax.json.JsonWriterFactory;
import javax.json.stream.JsonGenerator;

/**
 * The class demonstrates the usage of JsonObjectBuilder class
 * @author Ramesh Fadatare
 *
 */
public class JsonObjectBuilderExample {
    public static void main(String[] args) {
        String postedDate = LocalDate.of(2019, 7, 15).toString();

        JsonObjectBuilder jsonObjectBuilder = Json.createObjectBuilder()
            .add("id", "100")
            .add("title", "JSON-Processing API Post")
            .add("description", "JSON-Processing API Post")
            .add("postedDate", postedDate);

        JsonObject jsonObject = jsonObjectBuilder.build();


        Map < String, Boolean > config = new HashMap < String, Boolean > ();
        config.put(JsonGenerator.PRETTY_PRINTING, true);

        JsonWriterFactory jwf = Json.createWriterFactory(config);
        StringWriter sw = new StringWriter();

        try (JsonWriter jsonWriter = jwf.createWriter(sw)) {
            jsonWriter.writeObject(jsonObject);
            System.out.println(sw);
        }
    }
}

Output:

{
    "id": "100",
    "title": "JSON-Processing API Post",
    "description": "JSON-Processing API Post",
    "postedDate": "2019-07-15"
}

Let's understand the above example.

A JsonObjectBuilder is created with createObjectBuilder(). New pairs are inserted with add(). Finally, the JsonObject is created with build():

String postedDate = LocalDate.of(2019, 7, 15).toString();

JsonObjectBuilder jsonObjectBuilder = Json.createObjectBuilder()
		.add("id", "100")
		.add("title", "JSON-Processing API Post")
		.add("description", "JSON-Processing API Post")
		.add("postedDate", postedDate);

JsonObject jsonObject = jsonObjectBuilder.build();

Create JsonWriterFactory from createWriterFactory() method and pretty print the JSON with JsonGenerator.PRETTY_PRINTING settings:

Map<String, Boolean> config = new HashMap<String, Boolean>();
config.put(JsonGenerator.PRETTY_PRINTING, true);

JsonWriterFactory jwf = Json.createWriterFactory(config);
StringWriter sw = new StringWriter();

try (JsonWriter jsonWriter = jwf.createWriter(sw)) {
	jsonWriter.writeObject(jsonObject);
	System.out.println(sw);
}