jsp使用servlet实现文件上传

1.在index.jsp中写入以下代码

<form method="post" action="demo3" enctype="multipart/form-data">
    选择一个文件:
    <input type="file" name="uploadFile"/>
    <br/><br/>
    <input type="submit" value="上传"/>
</form>

2.在src中创建ServletDemo3类

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;//此三个包为 正常包以外 额外需要下载导入

public class ServletDemo3 extends HttpServlet {
    private static final long serialVersionUID = 1L;

    // 上传文件存储目录
    private static final String UPLOAD_DIRECTORY = "upload";

    // 上传配置
    private static final int MEMORY_THRESHOLD   = 1024 * 1024 * 3;  // 3MB
    private static final int MAX_FILE_SIZE      = 1024 * 1024 * 40; // 40MB
    private static final int MAX_REQUEST_SIZE   = 1024 * 1024 * 50; // 50MB

    /**
     * 上传数据及保存文件
     */
    protected void doPost(HttpServletRequest request,
                          HttpServletResponse response) throws ServletException, IOException {
        // 检测是否为多媒体上传
        if (!ServletFileUpload.isMultipartContent(request)) {
            // 如果不是则停止
            PrintWriter writer = response.getWriter();
            writer.println("Error: 表单必须包含 enctype=multipart/form-data");
            writer.flush();
            return;
        }

        // 配置上传参数
        DiskFileItemFactory factory = new DiskFileItemFactory();
        // 设置内存临界值 - 超过后将产生临时文件并存储于临时目录中
        factory.setSizeThreshold(MEMORY_THRESHOLD);
        // 设置临时存储目录
        factory.setRepository(new File(System.getProperty("java.io.tmpdir")));

        ServletFileUpload upload = new ServletFileUpload(factory);

        // 设置最大文件上传值
        upload.setFileSizeMax(MAX_FILE_SIZE);

        // 设置最大请求值 (包含文件和表单数据)
        upload.setSizeMax(MAX_REQUEST_SIZE);

        // 中文处理
        upload.setHeaderEncoding("UTF-8");

        // 构造临时路径来存储上传的文件
        // 这个路径相对当前应用的目录
        String uploadPath = request.getServletContext().getRealPath("./") + File.separator + UPLOAD_DIRECTORY;


        // 如果目录不存在则创建
        File uploadDir = new File(uploadPath);
        if (!uploadDir.exists()) {
            uploadDir.mkdir();
        }

        try {
            // 解析请求的内容提取文件数据
            @SuppressWarnings("unchecked")
            List<FileItem> formItems = upload.parseRequest(request);

            if (formItems != null && formItems.size() > 0) {
                // 迭代表单数据
                for (FileItem item : formItems) {
                    // 处理不在表单中的字段
                    if (!item.isFormField()) {
                        String fileName = new File(item.getName()).getName();
                        String filePath = uploadPath + File.separator + fileName;
                        File storeFile = new File(filePath);
                        // 在控制台输出文件的上传路径
                        System.out.println(filePath);
                        // 保存文件到硬盘
                        item.write(storeFile);
                        request.setAttribute("message",
                                "文件上传成功!");
                    }
                }
            }
        } catch (Exception ex) {
            request.setAttribute("message",
                    "错误信息: " + ex.getMessage());
        }
        // 跳转到 message.jsp
        request.getServletContext().getRequestDispatcher("/message.jsp").forward(
                request, response);
    }
    
}

3.在WEB-INF进行配置文件

    <servlet>
        <servlet-name>servletDemo3</servlet-name>
        <servlet-class>com.neunb.servlet.ServletDemo3</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>servletDemo3</servlet-name>
        <url-pattern>/demo3</url-pattern>
    </servlet-mapping>

4.创建message.jsp 显示上传结果

<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>文件上传结果</title>
</head>
<body>
    <h2>${message}</h2>
</body>
</html>

jsp使用servlet实现文件上传

1.在index.jsp中写入以下代码

2.在src中创建ServletDemo3类

3.在WEB-INF进行配置文件

4.创建message.jsp 显示上传结果

5.上传文件运行结果