javax.json: Generate json using JsonGenerator

 

JsonGenerator is used to generate json content and writes JSON data to an output source in a streaming way.

 

How to create a JsonGenerator?

You can create JsonGenerator by passing an output stream as argument to createGenerator method of Json class.

 

Example

ByteArrayOutputStream bos = new ByteArrayOutputStream();

JsonGenerator jsonGenerator = Json.createGenerator(bos);

 

How to generate json content?

‘JsonGenerator’ class provides multiple write* method to write json content.

 

jsonGenerator.writeStartObject();

Writes json start object character.

 

jsonGenerator.writeStartArray("hobbies");

Writes the JSON name/start array character pair with in the current object context.

 

jsonGenerator.writeEnd();

Writes the end of the current context. If the current context is an array context, this method writes the end-of-array character (']'). If the current context is an object context, this method writes the end-of-object character ('}').

 

Find the below working application.

 

JsonGeneratorDemo.java

package com.sample.app;

import java.io.ByteArrayOutputStream;
import java.io.IOException;

import javax.json.Json;
import javax.json.stream.JsonGenerator;

public class JsonGeneratorDemo {
        public static void main(String args[]) throws IOException {
                try (ByteArrayOutputStream bos = new ByteArrayOutputStream()) {

                        try (JsonGenerator jsonGenerator = Json.createGenerator(bos);) {

                                jsonGenerator.writeStartObject();

                                jsonGenerator.write("id", 123);
                                jsonGenerator.write("name", "Krishna");

                                // Write nested json document
                                jsonGenerator.writeStartObject("address").write("street", "Chodeswari").write("city", "Bangalore")
                                                .writeEnd();

                                // Write array content
                                jsonGenerator.writeStartArray("hobbies");
                                jsonGenerator.write("Cricket");
                                jsonGenerator.write("Chess");
                                jsonGenerator.writeEnd();

                                jsonGenerator.writeEnd();

                        }

                        String finalString = new String(bos.toByteArray());

                        System.out.println(finalString);

                }

        }

}

 

Output

{"id":123,"name":"Krishna","address":{"street":"Chodeswari","city":"Bangalore"},"hobbies":["Cricket","Chess"]}

 

 

 

 

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