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backend/src/main/java/com/example/demo/barcode/BarcodeProxyController.java

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+package com.example.demo.barcode;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.core.io.ByteArrayResource;
+import org.springframework.http.*;
+import org.springframework.http.client.SimpleClientHttpRequestFactory;
+import org.springframework.util.LinkedMultiValueMap;
+import org.springframework.util.MultiValueMap;
+import org.springframework.web.bind.annotation.*;
+import org.springframework.web.client.RestTemplate;
+import org.springframework.web.client.HttpStatusCodeException;
+import org.springframework.web.multipart.MultipartFile;
+
+import java.io.IOException;
+import java.time.Duration;
+
+@RestController
+@RequestMapping("/api/barcode")
+public class BarcodeProxyController {
+
+    private final PythonBarcodeProperties properties;
+    private final RestTemplate restTemplate;
+    private static final Logger log = LoggerFactory.getLogger(BarcodeProxyController.class);
+
+    public BarcodeProxyController(PythonBarcodeProperties properties) {
+        this.properties = properties;
+        SimpleClientHttpRequestFactory factory = new SimpleClientHttpRequestFactory();
+        factory.setConnectTimeout((int) Duration.ofSeconds(2).toMillis());
+        factory.setReadTimeout((int) Duration.ofSeconds(8).toMillis());
+        this.restTemplate = new RestTemplate(factory);
+    }
+
+    @PostMapping(value = "/scan", consumes = MediaType.MULTIPART_FORM_DATA_VALUE)
+    public ResponseEntity<String> scan(@RequestPart("file") MultipartFile file) throws IOException {
+        if (file == null || file.isEmpty()) {
+            return ResponseEntity.badRequest().body("{\"success\":false,\"message\":\"文件为空\"}");
+        }
+        long maxBytes = (long) properties.getMaxUploadMb() * 1024L * 1024L;
+        if (file.getSize() > maxBytes) {
+            return ResponseEntity.status(HttpStatus.PAYLOAD_TOO_LARGE)
+                    .body(String.format("{\"success\":false,\"message\":\"文件过大(> %dMB)\"}", properties.getMaxUploadMb()));
+        }
+        String url = String.format("http://%s:%d/api/barcode/scan", properties.getHost(), properties.getPort());
+        if (log.isDebugEnabled()) {
+            log.debug("转发条码识别请求: url={} filename={} size={}B", url, file.getOriginalFilename(), file.getSize());
+        }
+
+        // 构建 multipart/form-data 请求转发
+        MultiValueMap<String, Object> body = new LinkedMultiValueMap<>();
+        HttpHeaders fileHeaders = new HttpHeaders();
+        String contentType = file.getContentType();
+        MediaType mediaType = MediaType.APPLICATION_OCTET_STREAM;
+        if (contentType != null && !contentType.isBlank()) {
+            try {
+                mediaType = MediaType.parseMediaType(contentType);
+            } catch (Exception ignored) {
+                mediaType = MediaType.APPLICATION_OCTET_STREAM;
+            }
+        }
+        fileHeaders.setContentType(mediaType);
+        String originalName = file.getOriginalFilename();
+        if (originalName == null || originalName.isBlank()) {
+            originalName = file.getName();
+        }
+        if (originalName == null || originalName.isBlank()) {
+            originalName = "upload.bin";
+        }
+        fileHeaders.setContentDisposition(ContentDisposition.builder("form-data")
+                .name("file")
+                .filename(originalName)
+                .build());
+        final String finalFilename = originalName;
+        ByteArrayResource resource = new ByteArrayResource(file.getBytes()) {
+            @Override
+            public String getFilename() {
+                return finalFilename;
+            }
+        };
+        HttpEntity<ByteArrayResource> fileEntity = new HttpEntity<>(resource, fileHeaders);
+        body.add("file", fileEntity);
+
+        HttpHeaders headers = new HttpHeaders();
+        headers.setContentType(MediaType.MULTIPART_FORM_DATA);
+        HttpEntity<MultiValueMap<String, Object>> req = new HttpEntity<>(body, headers);
+
+        try {
+            long t0 = System.currentTimeMillis();
+            ResponseEntity<String> resp = restTemplate.postForEntity(url, req, String.class);
+            long cost = System.currentTimeMillis() - t0;
+            if (log.isDebugEnabled()) {
+                String bodyStr = resp.getBody();
+                if (bodyStr != null && bodyStr.length() > 500) {
+                    bodyStr = bodyStr.substring(0, 500) + "...";
+                }
+                log.debug("转发完成: status={} cost={}ms resp={}", resp.getStatusCodeValue(), cost, bodyStr);
+            }
+            return ResponseEntity.status(resp.getStatusCode())
+                    .contentType(MediaType.APPLICATION_JSON)
+                    .body(resp.getBody());
+        } catch (HttpStatusCodeException ex) {
+            String bodyStr = ex.getResponseBodyAsString();
+            if (bodyStr != null && bodyStr.length() > 500) {
+                bodyStr = bodyStr.substring(0, 500) + "...";
+            }
+            log.warn("Python 服务返回非 2xx: status={} body={}", ex.getStatusCode(), bodyStr);
+            MediaType respType = ex.getResponseHeaders() != null
+                    ? ex.getResponseHeaders().getContentType()
+                    : MediaType.APPLICATION_JSON;
+            if (respType == null) {
+                respType = MediaType.APPLICATION_JSON;
+            }
+            return ResponseEntity.status(ex.getStatusCode())
+                    .contentType(respType)
+                    .body(ex.getResponseBodyAsString());
+        } catch (Exception ex) {
+            // Python 服务不可用或超时等异常
+            log.warn("转发到 Python 服务失败: {}:{} path=/api/barcode/scan, err={}", properties.getHost(), properties.getPort(), ex.toString());
+            return ResponseEntity.status(HttpStatus.SERVICE_UNAVAILABLE)
+                    .contentType(MediaType.APPLICATION_JSON)
+                    .body("{\"success\":false,\"message\":\"识别服务不可用，请稍后重试\"}");
+        }
+    }
+}
+
+