Java文件上传-Apache Commons FileUpload工具包极速入门案例

<form action="upload" method="post" enctype="multipart/form-data">
    <input type="text" name="desc"><br>
    <input type="file" name="file"><br>
    <input type="submit">
</form>

@WebServlet("/upload")
public class FileServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // 创建磁盘文件项工厂
        DiskFileItemFactory diskFileItemFactory = new DiskFileItemFactory();

        // 创建一个ServletFileUpload
        ServletFileUpload servletFileUpload = new ServletFileUpload(diskFileItemFactory);

        // 解析request
        try {
            List<FileItem> fileItems = servletFileUpload.parseRequest(request);

            for (FileItem fileItem : fileItems) {
                if (fileItem.isFormField()) {
                    // 是否为表单输入项
                    String name = fileItem.getFieldName();
                    String value = fileItem.getString();
                    System.out.println("name:" + name + "----value:" + value);
                }else{
                    // 文件
                    // 拿到upload目录代表的File对象
                    File uploadedFile = new File(getServletContext().getRealPath("/upload"));

                    // 目录不存在则先创建一下
                    if (!uploadedFile.exists()) {
                        uploadedFile.mkdirs();
                    }

                    // 创建一个用来保存文件的File对象：在upload目录下使用原始文件名保存
                    // 比如上传的是 a.txt 则保存到 upload目录也是 a.txt（也可以取随机名，自行根据业务操作即可）
                    File file = new File(uploadedFile, fileItem.getName());
					// 写入文件
                    fileItem.write(file);
                }

            }
        } catch (FileUploadException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }