온라인 자바 컴파일러 만들기 (Judge0 API)

https://judge0.com

Judge0 - Where code happens.

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온라인 자바 컴파일러를 만들어 보고 싶었다. 찾아 보니 사용자가 입력한 코드를 컴파일해주는 Judge0 API가 이미 있어서 사용해보기로 했다. 위 사이트로 접속하여 다음 단계를 밟으면 API 키를 발급 받을 수 있다. 무료 버전을 사용하면 하루에 50개의 요청만 가능한 것 같다.

 

1. Get Started

2. Subscribe

3. Start Free Plan

4. API 키 확인

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스프링 부트 프로젝트 생성 - build.gradle

plugins {
    id 'java'
    id 'org.springframework.boot' version '3.3.1'
    id 'io.spring.dependency-management' version '1.1.5'
}

group = 'project'
version = '0.0.1-SNAPSHOT'

java {
    toolchain {
        languageVersion = JavaLanguageVersion.of(17)
    }
}

configurations {
    compileOnly {
        extendsFrom annotationProcessor
    }
}

repositories {
    mavenCentral()
}

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-thymeleaf'
    implementation 'org.springframework.boot:spring-boot-starter-web'
    implementation 'org.springframework.boot:spring-boot-starter-webflux'
    compileOnly 'org.projectlombok:lombok'
    developmentOnly 'org.springframework.boot:spring-boot-devtools'
    annotationProcessor 'org.projectlombok:lombok'
    testImplementation 'org.springframework.boot:spring-boot-starter-test'
    testRuntimeOnly 'org.junit.platform:junit-platform-launcher'

    if (isAppleSilicon()) {
        runtimeOnly("io.netty:netty-resolver-dns-native-macos:4.1.94.Final:osx-aarch_64")
    }
}

def isAppleSilicon() {
    return System.getProperty("os.name") == "Mac OS X" && System.getProperty("os.arch") == "aarch64"
}

tasks.named('test') {
    useJUnitPlatform()
}

 

CompilerController

@Controller
public class CompilerController {

    private final WebClient webClient;

    public CompilerController(WebClient.Builder webClientBuilder, @Value("${apiKey}") String key) {
        this.webClient = webClientBuilder
                .baseUrl("https://judge0-ce.p.rapidapi.com")
                .defaultHeader("x-rapidapi-key", key)
                .defaultHeader("x-rapidapi-host", "judge0-ce.p.rapidapi.com")
                .build();
    }

    @GetMapping("/")
    public String index(Model model) {
        String defaultCode = """
            public class Main {
                public static void main(String[] args) {
                    System.out.println("Hello, World!");
                }
            }
            """;
        model.addAttribute("sourceCode", defaultCode);
        return "index";
    }

    @PostMapping("/compile")
    public Mono<ResponseEntity<Map<String, String>>> compileCode(@RequestBody Map<String, String> requestBody) {
        String sourceCode = requestBody.get("sourceCode");
        String encodedSourceCode = Base64.getEncoder().encodeToString(sourceCode.getBytes());

        Map<String, String> requestPayload = new HashMap<>();
        requestPayload.put("language_id", "62"); // Java
        requestPayload.put("source_code", encodedSourceCode);
        requestPayload.put("stdin", "");

        return this.webClient.post()
                .uri("/submissions?base64_encoded=true&wait=false")
                .contentType(MediaType.APPLICATION_JSON)
                .bodyValue(requestPayload)
                .retrieve()
                .bodyToMono(Map.class)
                .flatMap(response -> {
                    String token = (String) response.get("token");
                    return checkResult(token);
                })
                .map(result -> {
                    Map<String, String> responseMap = new HashMap<>();
                    StringBuilder output = new StringBuilder();
                    String stdout = (String) result.get("stdout");
                    String stderr = (String) result.get("stderr");
                    String compileOutput = (String) result.get("compile_output");
                    String message = (String) result.get("message");


                    if (stdout != null) {
                        output.append(new String(Base64.getDecoder().decode(stdout)));
                    }
                    if (stderr != null) {
                        output.append(new String(Base64.getDecoder().decode(stderr)));
                    }
                    if (compileOutput != null) {
                        output.append(new String(Base64.getDecoder().decode(compileOutput)));
                    }
                    if (message != null) {
                        output.append(message);
                    }

                    responseMap.put("output", output.toString());
                    return ResponseEntity.ok(responseMap);
                })
                .onErrorResume(e -> {
                    Map<String, String> responseMap = new HashMap<>();
                    responseMap.put("output", "An error occurred: " + e.getMessage());
                    return Mono.just(ResponseEntity.ok(responseMap));
                });
    }

    private Mono<Map> checkResult(String token) {
        return this.webClient.get()
                .uri("/submissions/" + token + "?base64_encoded=true")
                .retrieve()
                .bodyToMono(Map.class);
    }
}

 

index.html

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>Online Java Compiler</title>
    <link rel="icon" href="/icon/duke.ico" type="image/x-icon">
    <script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>
    <script>
        $(document).ready(function() {
            $("form").on("submit", function(event) {
                event.preventDefault();
                $.ajax({
                    type: "POST",
                    url: "/compile",
                    contentType: "application/json",
                    data: JSON.stringify({
                        sourceCode: $("#sourceCode").val()
                    }),
                    success: function(response) {
                        $("#output").text(response.output);
                    },
                    error: function() {
                        $("#output").text("An error occurred while compiling the code.");
                    }
                });
            });
        });
    </script>
</head>
<body>
<h1>Online Java Compiler!!</h1>
<form>
    <textarea id="sourceCode" name="sourceCode" rows="20" cols="80" placeholder="Enter your Java code here" th:text="${sourceCode}"></textarea><br/>
    <button type="submit">Compile</button>
</form>
<h2>Result:</h2>
<pre id="output" th:text="${output}"></pre>
</body>
</html>