使用java进行文件上传的Post调用未按预期工作

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;
import java.util.List;

public class FileUploadServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 检查是否为文件上传请求
        boolean isMultipart = ServletFileUpload.isMultipartContent(request);

        if (isMultipart) {
            // 创建文件上传工厂
            DiskFileItemFactory factory = new DiskFileItemFactory();

            // 设置临时文件存储目录
            String tempDir = "path/to/temp/dir";
            factory.setRepository(new File(tempDir));

            // 创建文件上传处理器
            ServletFileUpload upload = new ServletFileUpload(factory);

            try {
                // 解析文件上传请求
                List<FileItem> items = upload.parseRequest(request);

                // 处理文件上传
                for (FileItem item : items) {
                    if (!item.isFormField()) {
                        // 获取文件名
                        String fileName = item.getName();

                        // 保存文件到指定目录
                        String uploadDir = "path/to/upload/dir";
                        File file = new File(uploadDir, fileName);
                        item.write(file);
                    }
                }

                // 文件上传成功
                response.getWriter().write("File uploaded successfully.");
            } catch (Exception e) {
                // 文件上传失败
                response.getWriter().write("File upload failed.");
            }
        } else {
            // 非文件上传请求
            response.getWriter().write("Not a file upload request.");
        }
    }
}