如何在java服务器上中止文件上传？

import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.StandardCopyOption;

@WebServlet("/upload")
public class FileUploadServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    
    private static final String UPLOAD_DIR = "/path/to/upload/directory";
    private static volatile boolean stopUpload = false;

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 检查是否需要中止文件上传
        if (stopUpload) {
            // 返回中止上传的响应
            response.setStatus(HttpServletResponse.SC_CONFLICT);
            return;
        }
        
        // 创建上传目录（如果不存在）
        Path uploadPath = Paths.get(UPLOAD_DIR);
        if (!Files.exists(uploadPath)) {
            Files.createDirectories(uploadPath);
        }
        
        // 获取上传的文件
        Part filePart = request.getPart("file");
        String fileName = filePart.getSubmittedFileName();
        
        // 保存文件到服务器
        try (InputStream fileContent = filePart.getInputStream()) {
            Path filePath = uploadPath.resolve(fileName);
            Files.copy(fileContent, filePath, StandardCopyOption.REPLACE_EXISTING);
        }
        
        // 文件上传成功的处理逻辑
        // ...
    }
    
    protected void doPut(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 设置标志位，中止文件上传
        stopUpload = true;
        
        // 返回中止上传的响应
        response.setStatus(HttpServletResponse.SC_OK);
    }
}