import org.springframework.core.io.FileSystemResource;
import org.springframework.core.io.Resource;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.resource.ResourceHttpRequestHandler;

import javax.servlet.http.HttpServletRequest;
import java.nio.file.Path;

@Component
public class NonStaticResourceHttpRequestHandler extends ResourceHttpRequestHandler {

  public final static String ATTR_FILE = "NON-STATIC-FILE";

  @Override
  protected Resource getResource(HttpServletRequest request) {
    final Path filePath = (Path) request.getAttribute(ATTR_FILE);
    return new FileSystemResource(filePath);
  }

}

@RestController
@AllArgsConstructor
public class FileRestController {

  private final NonStaticResourceHttpRequestHandler nonStaticResourceHttpRequestHandler;

  /**
   * 預(yù)覽視頻文件, 支持 byte-range 請求
   */
  @GetMapping("/video")
  public void videoPreview(HttpServletRequest request, HttpServletResponse response) throws Exception {
    String path = request.getParameter("path");
    Path filePath = Paths.get(path);
    if (Files.exists(filePath)) {
      String mimeType = Files.probeContentType(filePath);
      if (!StringUtils.isEmpty(mimeType)) {
        response.setContentType(mimeType);
      }
      request.setAttribute(NonStaticResourceHttpRequestHandler.ATTR_FILE, filePath);
      nonStaticResourceHttpRequestHandler.handleRequest(request, response);
    } else {
      response.setStatus(HttpServletResponse.SC_NOT_FOUND);
      response.setCharacterEncoding(StandardCharsets.UTF_8.toString());
    }
  }

}