【Java】JSON 通信 with jackson

java で json の通信を行う (jackson を利用)

環境

• windows10
• eclipse：2020-06 (4.16.0)
• jackson
• java 1.8

例によって忘備録です・・・

順序

1. Dto 生成
2. jackson を使って Dto -> json に変換
3. HttpURLConnection を使って通信
4. 結果取得

Dto 生成

public class SampleDto implements Serializable {
    private static final long serialVersionUID = 1L;　 // ちゃんと生成した方が良さげ

    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 変換

    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));
            log.error(sw.toString());
            return null;
        }
    }

通信

    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.setRequestMethod(method);
            con.setUseCaches(false);
            con.setDoOutput(true);
            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()));
            out.write(json);
            out.close();

            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));
            log.error(sw.toString());
            return null;
        }
        finally {
            if (con != null) {
                con.disconnect();
            }
        }
        return body;
    }

結果取得

    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));
            log.error(sw.toString());
            return false;
        }
        return true;
    }

以上、お疲れさまでした！