Java 11 대표 코드

HTTP 클라이언트 API 도입

// HTTP 클라이언트 생성
HttpClient httpClient = HttpClient.newHttpClient();

// GET
HttpRequest getRequest = HttpRequest.newBuilder()
        .uri(new URI("https://backend.opsnow.com:9137/api/menu/list"))
        .header("Authorization", "Bearer *********")
        .GET()
        .build();
HttpResponse<String> response = httpClient.send(getRequest, HttpResponse.BodyHandlers.ofString());

// =====================================================================================

// POST
// Payload 1 - DTO
User user = User.builder()
								.name("양승길")
								.email("seunggil.yang@bespinglobal.com")
								.build();
ObjectMapper objectMapper = new ObjectMapper();
String requestBody = objectMapper.writeValueAsString(user);

// Payload 2 - JSONObject
JSONObject jsonRequest = new JSONObject();
jsonRequest.put("field1", "value1");
jsonRequest.put("field2", "value2");
String requestBody = jsonRequest.toString();

// Payload 3 - Map
Map<String, String> requestData = Map.of(
		"field1", "value1",
		"field2", "value2"
);
String requestBody = new JSONObject(map).toString();


// POST 요청 생성
HttpRequest postRequest = HttpRequest.newBuilder()
        .uri(new URI("https://backend.opsnow.com:9137/api/join"))
        .header("Authorization", "Bearer *********")
        .header("Content-Type", "application/json")
        .POST(HttpRequest.BodyPublishers.ofString(requestBody))
        .build();

HttpResponse<String> response = httpClient.send(postRequest, HttpResponse.BodyHandlers.ofString());

// =====================================================================================

// 응답 처리
if (response.statusCode() == 200) {
    System.out.println("POST Response Body: " + response.body());
		ObjectMapper objectMapper = new ObjectMapper();
    ResponseDto response = objectMapper.readValue(response.body(), ResponseDto.class);
} else {
    System.err.println("POST Request Failed with Status Code: " + response.statusCode());
}

String 관련 메서드 추가

// 1. 공백 확인
String str = "   ";
boolean isBlank = str.isBlank(); // true

// 2. 앞뒤 공백 제거
String str = "  Hello, World!  ";
String stripped = str.strip(); // "Hello, World!"

// trim()과의 차이
// strip() - 공백(space), 탭(tab), 줄 바꿈(newline) 등의 유니코드 공백 문자 제거
// trim() - 공백(space), 탭(tab)만 제거

// 3. 반복
String repeated = "abc".repeat(3); // "abcabcabc"

// 4. List화
String multiLineString = "Line 1\nLine 2\r\nLine 3";
List<String> lines = multiLineString.lines()
        .collect(Collectors.toList());

// 5. 포맷
String formattedString = "Hello, %s! Today is %d %s.".formatted("John", 22, "September");