대용량 다운로드 테스트

src/main/java/com/kamco/cd/kamcoback/common/download/DownloadExecutor.java

@@ -0,0 +1,48 @@
+package com.kamco.cd.kamcoback.common.download;
+
+import com.kamco.cd.kamcoback.common.download.dto.DownloadSpec;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.MediaType;
+import org.springframework.http.ResponseEntity;
+import org.springframework.stereotype.Service;
+import org.springframework.web.servlet.mvc.method.annotation.StreamingResponseBody;
+
+@Service
+@RequiredArgsConstructor
+public class DownloadExecutor {
+
+  public ResponseEntity<StreamingResponseBody> stream(DownloadSpec spec) throws IOException {
+
+    if (!Files.isReadable(spec.filePath())) {
+      return ResponseEntity.notFound().build();
+    }
+
+    long fileSize = Files.size(spec.filePath());
+
+    StreamingResponseBody body =
+        os -> {
+          try (InputStream in = Files.newInputStream(spec.filePath())) {
+            in.transferTo(os);
+            os.flush();
+          } catch (Exception e) {
+            // 고용량은 중간 끊김 흔하니까 throw 금지
+          }
+        };
+
+    String fileName =
+        spec.downloadName() != null
+            ? spec.downloadName()
+            : spec.filePath().getFileName().toString();
+
+    return ResponseEntity.ok()
+        .contentType(
+            spec.contentType() != null ? spec.contentType() : MediaType.APPLICATION_OCTET_STREAM)
+        .contentLength(fileSize)
+        .header(HttpHeaders.CONTENT_DISPOSITION, "attachment; filename=\"" + fileName + "\"")
+        .body(body);
+  }
+}

src/main/java/com/kamco/cd/kamcoback/common/download/dto/DownloadSpec.java

@@ -0,0 +1,12 @@
+package com.kamco.cd.kamcoback.common.download.dto;
+
+import java.nio.file.Path;
+import java.util.UUID;
+import org.springframework.http.MediaType;
+
+public record DownloadSpec(
+    UUID uuid, // 다운로드 식별(로그/정책용)
+    Path filePath, // 실제 파일 경로
+    String downloadName, // 사용자에게 보일 파일명
+    MediaType contentType // 보통 OCTET_STREAM
+    ) {}