[Java] JSON communication with jackson

Communicate json with java (using jackson)


As usual, it's a memorandum ...


  1. Dto generation
  2. Convert to Dto-> json using jackson
  3. Communicate using HttpURLConnection
  4. Get results

Dto generation

public class SampleDto implements Serializable {
    private static final long serialVersionUID = 1L;  //It is better to generate it properly

    private int id;
    private String mail;

	public int getId() {
		return id;
	public void setId(int id) {
		this.id = id;
	public String getMail() {
		return mail;
	public void setMail(String mail) {
		this.mail = mail;

Dto-> json conversion

	protected String createJson4Sample(SampleDto dto) {

		ObjectMapper mapper = new ObjectMapper();
		try {
			return mapper.writerWithDefaultPrettyPrinter().writeValueAsString(dto);
		} catch (JsonProcessingException e) {
			StringWriter sw = new StringWriter();
			e.printStackTrace(new PrintWriter(sw));
			return null;


	protected String requestJson(String method, String json, String urlPath, String charset,
			String bearer) {

		HttpURLConnection con = null;
		if (StringUtils.isEmpty(charset)) {
			charset = StringUtils.lowerCase(StandardCharsets.UTF_8.name());
		String body = "";
		try {
			URL url = new URL(urlPath);
			con = (HttpURLConnection)url.openConnection();
			con.setRequestProperty("Content-Type", "application/json; charset=" + charset);
			if (StringUtils.isNotEmpty(bearer)) {
				con.setRequestProperty("Authorization", "Bearer "+bearer);

			OutputStreamWriter out = new OutputStreamWriter(new BufferedOutputStream(con.getOutputStream()));

			BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
			String line = in.readLine();
			while (line != null) {
				body = body + line;
				line = in.readLine();
		catch (Exception e) {
			StringWriter sw = new StringWriter();
			e.printStackTrace(new PrintWriter(sw));
			return null;
		finally {
			if (con != null) {
		return body;

Get results

	protected boolean checkResponseJson(String response) {

		ObjectMapper mapper = new ObjectMapper();
		try {
			if (StringUtils.isEmpty(response)) { return false; }
			JsonNode root = mapper.readTree(response);

			String success = root.get("success").asText();
			String id = root.get("id").asText();
			log.info("Response:" + id + ":" + success);
			if (!"OK".equalsIgnoreCase(success)) {
				return false;
		} catch (Exception e) {
			StringWriter sw = new StringWriter();
			e.printStackTrace(new PrintWriter(sw));
			return false;
		return true;

Thank you for your hard work!

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