How to Encode and Decode JSON Byte Array

Amir Ghahrai

Amir Ghahrai

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The typical way to send binary in JSON is to base64 encode it. Java provides different ways to Base64 encode and decode a byte[]. One of these is DatatypeConverter.

Suppose we have a JSON Array as listed below:

{
    "menu": {
        "id": "file",
        "value": "File",
        "popup": {
            "menuitem": [
                {"value": "New", "onclick": "CreateNewDoc()"},
                {"value": "Open", "onclick": "OpenDoc()"},
                {"value": "Close", "onclick": "CloseDoc()"}
            ]
        }
    }
}

Encode JSON as Base64

To encode the above JSON, we would use

String base64Encoded = DatatypeConverter.printBase64Binary(jsonBytes);

Decode Base64 JSON

To decode a base64 encoded JSON, we would use

byte[] base64Decoded = DatatypeConverter.parseBase64Binary(base64Encoded);

Example code:

import javax.xml.bind.DatatypeConverter;

public class JsonEncodeDecode {

    public static void main(String[] args) {
        String json = "{\"menu\": {\n" +
                "  \"id\": \"file\",\n" +
                "  \"value\": \"File\",\n" +
                "  \"popup\": {\n" +
                "    \"menuitem\": [\n" +
                "      {\"value\": \"New\", \"onclick\": \"CreateNewDoc()\"},\n" +
                "      {\"value\": \"Open\", \"onclick\": \"OpenDoc()\"},\n" +
                "      {\"value\": \"Close\", \"onclick\": \"CloseDoc()\"}\n" +
                "    ]\n" +
                "  }\n" +
                "}}";

        byte[] bytes = json.getBytes();

        String base64Encoded = DatatypeConverter.printBase64Binary(bytes);
        System.out.println("Encoded Json:\n");
        System.out.println(base64Encoded + "\n");

        byte[] base64Decoded = DatatypeConverter.parseBase64Binary(base64Encoded);
        System.out.println("Decoded Json:\n");
        System.out.println(new String(base64Decoded));
    }
}

Output of encoded JSON:

eyJtZW51IjogewogICJpZCI6ICJmaWxlIiwKICAidmFsdW

Output of decoded JSON:

{
    "menu": {
        "id": "file",
        "value": "File",
        "popup": {
            "menuitem": [
                {"value": "New", "onclick": "CreateNewDoc()"},
                {"value": "Open", "onclick": "OpenDoc()"},
                {"value": "Close", "onclick": "CloseDoc()"}
            ]
        }
    }
}
#java #json