Android 오라클 데이터베이스 데이터 JSON 가져오기

<AndroidManifest.xml>

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.database_connection_activity">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:usesCleartextTraffic="true"
        android:theme="@style/Theme.DataBase_Connection_Activity">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

</manifest>

public class RegisterActivity extends AsyncTask<Map<String, String>, Integer, String> {

    //public static String ip = "10.0.2.2"; // 자신의 IP주소를 쓰시면 됩니다.

    @Override
    protected String doInBackground(Map<String, String>... maps) {
        // Http 요청 준비 작업
        HttpClient.Builder http = new HttpClient.Builder
                ("POST", "http://" + ip + ":8080/count"); //포트번호,서블릿주소


        // Parameter 를 전송한다.
        //http.addAllParameters(maps[0]);

        //Http 요청 전송
        HttpClient post = http.create();
        post.request();

        // 응답 상태코드 가져오기
        int statusCode = post.getHttpStatusCode();

        // 응답 본문 가져오기
        String body = post.getBody();

        Type type = new TypeToken<ArrayList<Vision>>(){}.getType();
        Gson gson = new Gson();
        ArrayList<Vision> data = gson.fromJson(body, type);

        System.out.println("data : "+data.get(0).getTtt());
        System.out.println("Body : "+body);

        for(int index=0; index<data.size(); index++){
            System.out.println("VO COUNT : "+data.get(index).getCount());
            System.out.println("VO TTT : "+data.get(index).getTtt());
        }

        return body;
    }

    @Override
    protected void onPostExecute(String s) { //서블릿으로부터 값을 받을 함수

        System.out.println("???????" + s);

        Type type = new TypeToken<ArrayList<Vision>>(){}.getType();
        Gson gson = new Gson();
        //Vision data = gson.fromJson(s, Vision.class);
        ArrayList<Vision> data = gson.fromJson(s, type);//Collection

       // System.out.println("번호 : "+data.size());

    }
}

public class HttpClient {
    private static final String WWW_FORM = "application/x-www-form-urlencoded";

    private int httpStatusCode;
    private String body;

    public int getHttpStatusCode() {
        return httpStatusCode;
    }

    public String getBody() {
        return body;
    }

    private Builder builder;

    private void setBuilder(Builder builder) {
        this.builder = builder;
    }

    public void request() {
        HttpURLConnection conn = getConnection();
        setHeader(conn);
        setBody(conn);
        httpStatusCode = getStatusCode(conn);
        body = readStream(conn);
        conn.disconnect();
    }

    private HttpURLConnection getConnection() {
        try {
            URL url = new URL(builder.getUrl());
            return (HttpURLConnection) url.openConnection();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }

    private void setHeader(HttpURLConnection connection) {
        setContentType(connection);
        setRequestMethod(connection);

        connection.setConnectTimeout(5000);
        connection.setDoOutput(true);
        connection.setDoInput(true);
    }

    private void setContentType(HttpURLConnection connection) {
        connection.setRequestProperty("Content-Type", WWW_FORM);
    }

    private void setRequestMethod(HttpURLConnection connection) {
        try {
            connection.setRequestMethod(builder.getMethod());
        } catch (ProtocolException e) {
            e.printStackTrace();
        }
    }

    private void setBody(HttpURLConnection connection) {

        String parameter = builder.getParameters();
        if ( parameter != null && parameter.length() > 0 ) {
            OutputStream outputStream = null;
            try {
                outputStream = connection.getOutputStream();
                outputStream.write(parameter.getBytes("UTF-8"));
                outputStream.flush();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
                try {
                    if ( outputStream != null )
                        outputStream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

    }

    private int getStatusCode(HttpURLConnection connection) {
        try {
            return connection.getResponseCode();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return -10;
    }

    private String readStream(HttpURLConnection connection) {
        String result = "";
        BufferedReader reader = null;
        try {
            reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String line = null;
            while ( (line = reader.readLine()) != null ) {
                result += line;
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if(reader != null)
                    reader.close();
            } catch (IOException e) {}
        }

        return result;
    }

    public static class Builder {

        private Map<String, String> parameters;
        private String method;
        private String url;

        public String getMethod() {
            return method;
        }

        public String getUrl() {
            return url;
        }

        public Builder(String method, String url) {
            if(method == null) {
                method = "GET";
            }
            this.method = method;
            this.url = url;
            this.parameters = new HashMap<String, String>();
        }

        public void addOrReplace(String key, String value) {
            this.parameters.put(key, value);
        }

        public void addAllParameters(Map<String, String> param) {
            this.parameters.putAll(param);
        }

        public String getParameters() {
            return generateParameters();
        }

        public String getParameter(String key) {
            return this.parameters.get(key);
        }

        private String generateParameters() {
            StringBuffer parameters = new StringBuffer();

            Iterator<String> keys = getKeys();

            String key = "";
            while ( keys.hasNext() ) {
                key = keys.next();
                parameters.append(String.format("%s=%s", key, this.parameters.get(key)));
                parameters.append("&");
            }

            String params = parameters.toString();
            if ( params.length() > 0 ) {
                params = params.substring( 0, params.length() - 1 );
            }

            return params;
        }

        private Iterator<String> getKeys() {
            return this.parameters.keySet().iterator();
        }

        public HttpClient create() {
            HttpClient client = new HttpClient();
            client.setBuilder(this);
            return client;
        }
    }
}