RestTemplate 구현

외부 API 구현

서버 간 통신을 실습하기 위해 별도의 프로젝트를 하나 더 생성해준다.

application.properties 파일에 server.port=9090 으로 설정해 2개의 서버를 사용할 수 있게 세팅

serverbox.controller.CrudController.java

@RestController
@RequestMapping("/api/v1/crud-api")
public class CrudController {
    @GetMapping
    public String getName(){
        return "Flature";
    }

    @GetMapping(value = "/{variable}")
    public String getVariable(@PathVariable String variable){
        return variable;
    }

    @GetMapping("/param")
    public String getNameWithParam(@RequestParam String name){
        return "Hello." + name + "!";
    }

    @PostMapping
    public ResponseEntity<MemberDto> getMember(
            @RequestBody MemberDto request,
            @RequestParam String name,
            @RequestParam String email,
            @RequestParam String organization
    ){
        System.out.println(request.getName());
        System.out.println(request.getEmail());
        System.out.println(request.getOrganization());


        MemberDto memberDto = new MemberDto();
        memberDto.setName(name);
        memberDto.setEmail(email);
        memberDto.setOrganization(organization);

        return ResponseEntity.status(HttpStatus.OK).body(memberDto);

    }

    @PostMapping(value = "/add-header")
    public ResponseEntity<MemberDto> addHeader(@RequestHeader("my-header") String header, @RequestBody MemberDto memberDto){
        System.out.println(header);
        return ResponseEntity.status(HttpStatus.OK).body(memberDto);
    }
}

serverbox.dto.MemberDto.java

public class MemberDto {
    public String name;
    public String email;
    public String organization;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getOrganization() {
        return organization;
    }

    public void setOrganization(String organization) {
        this.organization = organization;
    }

    @Override
    public String toString() {
        return "MemberDto{" +
                "name='" + name + '\'' +
                ", email='" + email + '\'' +
                ", organization='" + organization + '\'' +
                '}';
    }
}

RestTemplate 구현

GET 형식의 RestTemplate

rest.service.RestTemplateService.java

@Service
public class RestTemplateService {
    public String getName(){
        URI uri = UriComponentsBuilder
                .fromUriString("http://localhost:9090")
                .path("/api/v1/crud-api")
                .encode()
                .build()
                .toUri();
        RestTemplate restTemplate = new RestTemplate();
        ResponseEntity<String> responseEntity = restTemplate.getForEntity(uri,String.class);

        return responseEntity.getBody();
    }

    public String getNameWithPathVariable(){
        URI uri = UriComponentsBuilder
                .fromUriString("http://localhost:9090")
                .path("/api/v1/crud-api/{name}")
                .encode()
                .build()
                .expand("Flature")
                .toUri();
        RestTemplate restTemplate = new RestTemplate();
        ResponseEntity<String> responseEntity = restTemplate.getForEntity(uri,String.class);

        return responseEntity.getBody();
    }

    public String getNameWithParameter(){
        URI uri = UriComponentsBuilder
                .fromUriString("http://localhost:9090")
                .path("/api/v1/crud-api/param")
                .queryParam("name", "Flature")
                .encode()
                .build()
                .toUri();
        RestTemplate restTemplate = new RestTemplate();
        ResponseEntity<String> responseEntity = restTemplate.getForEntity(uri,String.class);

        return responseEntity.getBody();
    }
}

UriComponentsBuilder로 빌더 형식으로 URI 객체를 만드는 것을 확인할 수 있다.
fromUriString() 호출부의 URL 입력
path() 세부 경로 입력
encode() 인코딩 문자셋 설정(미설정 시 UTF-8)
build() 빌더 생성을 종료하고 UriComponent 타입이 리턴된다.
toUri() URI 타입으로 리턴
toUriString() String 타입으로 리턴

expand() path 메소드 내에 {}를 사용해 변수명을 입력 하고 expand() 메소드에서 변수 값을 입력해 준다.
queryParam() 키, 값 형식의 파라미터를 추가할 수 있다.

POST 형식 RestTemplate

public ResponseEntity<MemberDto> postWithParamAndBody(){
        URI uri = UriComponentsBuilder
                .fromUriString("http://localhost:9090")
                .path("/api/v1/crud-api/param")
                .queryParam("name", "Flature")
                .queryParam("email", "flature@wikibooks.co.kr")
                .queryParam("organization", "Wikibooks")
                .encode()
                .build()
                .toUri();

        MemberDto memberDto = new MemberDto();
        memberDto.setName("flature!");
        memberDto.setEmail("flature@gmail.com");
        memberDto.setOrganization("Around Hub Studio");

        RestTemplate restTemplate = new RestTemplate();
        ResponseEntity<MemberDto> responseEntity = restTemplate.postForEntity(uri,memberDto,MemberDto.class);
        return responseEntity;
    }

    public ResponseEntity<MemberDto> postWithHeader(){
        URI uri = UriComponentsBuilder
                .fromUriString("http://localhost:9090")
                .path("/api/v1/crud-api")
                .encode()
                .build()
                .toUri();

        MemberDto memberDto = new MemberDto();
        memberDto.setName("flature!");
        memberDto.setEmail("flature@gmail.com");
        memberDto.setOrganization("Around Hub Studio");

        RequestEntity<MemberDto> requestEntity = RequestEntity
                .post(uri)
                .header("my-header","Wikibooks API")
                .body(memberDto);

        RestTemplate restTemplate = new RestTemplate();

        ResponseEntity<MemberDto> responseEntity = restTemplate.exchange(requestEntity, MemberDto.class);
        return responseEntity;
    }

POST 형식으로 요청하기 위해 파라미터 값과 Body 값을 담는 방법
queryParam 을 이용해 파라미터를 전달하고
객체를 만들어서 postForEntity에 담아 전달한다.

RestTemplateController 생성

서비스 코드를 연결하는 컨트롤러 코드 생성

@RestController
@RequestMapping("/rest-template")
public class RestTemplateController {
    private final RestTemplateService restTemplateService;

    public RestTemplateController(RestTemplateService restTemplateService){
        this.restTemplateService = restTemplateService;
    }

    @GetMapping
    public String getName(){
        return restTemplateService.getName();
    }
    @GetMapping("/path-variable")
    public String getNameWithPathVariable(){
        return restTemplateService.getNameWithPathVariable();
    }
    @GetMapping("/parameter")
    public String getNameWithParameter(){
        return restTemplateService.getNameWithParameter();
    }

    @PostMapping
    public ResponseEntity<MemberDto> postDto(){
        return restTemplateService.postWithParamAndBody();
    }

    @PostMapping("/header")
    public ResponseEntity<MemberDto> postWithHeader(){
        return restTemplateService.postWithHeader();
    }

}

실행결과

다음과 같이 serverbox 메소드를 활용해 출력결과가 제대로 나오는 것을 확인할 수 있다.