Java API 개발 실습: 데이터 전송에 HTTP 프로토콜을 사용하는 방법은 무엇입니까?

import java.io.BufferedReader; import java.io.InputStreamReader; import java.net.HttpURLConnection; import java.net.URL; public class HttpURLConnectionExample { private static final String USER_AGENT = "Mozilla/5.0"; public static void main(String[] args) throws Exception { String url = "http://www.example.com"; URL obj = new URL(url); HttpURLConnection con = (HttpURLConnection) obj.openConnection(); con.setRequestMethod("GET"); con.setRequestProperty("User-Agent", USER_AGENT); int responseCode = con.getResponseCode(); System.out.println("Response Code : " + responseCode); BufferedReader in = new BufferedReader( new InputStreamReader(con.getInputStream())); String inputLine; StringBuffer response = new StringBuffer(); while ((inputLine = in.readLine()) != null) { response.append(inputLine); } in.close(); System.out.println(response.toString()); } }

import org.apache.http.HttpEntity; import org.apache.http.client.methods.CloseableHttpResponse; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import org.apache.http.util.EntityUtils; public class ApacheHttpClientExample { public static void main(String[] args) throws Exception { CloseableHttpClient httpclient = HttpClients.createDefault(); HttpGet httpget = new HttpGet("http://www.example.com"); CloseableHttpResponse response = httpclient.execute(httpget); try { HttpEntity entity = response.getEntity(); if (entity != null) { System.out.println(EntityUtils.toString(entity)); } } finally { response.close(); } } }

import okhttp3.OkHttpClient; import okhttp3.Request; import okhttp3.Response; import java.io.IOException; public class OkHttpExample { private final OkHttpClient httpClient = new OkHttpClient(); public static void main(String[] args) throws IOException { OkHttpExample http = new OkHttpExample(); System.out.println("Sending GET request..."); String response = http.sendGet("http://www.example.com"); System.out.println(response); } private String sendGet(String url) throws IOException { Request request = new Request.Builder() .url(url) .build(); try (Response response = httpClient.newCall(request).execute()) { if (!response.isSuccessful()) throw new IOException("Unexpected code " + response); return response.body().string(); } } }