ssm文件上传下载

核心依赖

<!--文件上传-->
        <dependency>
            <groupId>commons-fileupload</groupId>
            <artifactId>commons-fileupload</artifactId>
            <version>1.4</version>
        </dependency>

导入依赖后 若是报500的错记得在项目结构里加入jar包，
file-project structure-modules

配置文件中须要添加

<!--文件上传配置-->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <!-- 请求的编码格式，必须和jSP的pageEncoding属性一致，以便正确读取表单的内容，默认为ISO-8859-1 -->
        <property name="defaultEncoding" value="utf-8"/>
        <!-- 上传文件大小上限，单位为字节（10485760=10M） -->
        <property name="maxUploadSize" value="10485760"/>
        <property name="maxInMemorySize" value="40960"/>
    </bean>

文件上传代码

@RequestMapping("/upload2")
    public String fileUpload2(@RequestParam("file") CommonsMultipartFile file, HttpServletRequest request) throws IOException {

        //上传路径保存设置
        // String path = request.getServletContext().getRealPath("/upload");
        String path = "D:\\360";
        File realPath = new File(path);
        System.out.println("上传文件保存地址：" + realPath);
        if (!realPath.exists()) {
            realPath.mkdir();
        }
        //上传文件地址
        System.out.println("上传文件保存地址：" + realPath);

        //经过CommonsMultipartFile的方法直接写文件（注意这个时候）
        file.transferTo(new File(realPath + "/" + file.getOriginalFilename()));

        return "redirect:/index.jsp";
    }

文件下载代码

@RequestMapping(value = "/download")
    public String downloads(HttpServletResponse response, HttpServletRequest request) throws Exception {
        //要下载的图片地址
        String path = request.getServletContext().getRealPath("/upload");
        String fileName = "基础语法.jpg";

        //一、设置response 响应头
        response.reset(); //设置页面不缓存,清空buffer
        response.setCharacterEncoding("UTF-8"); //字符编码
        response.setContentType("multipart/form-data"); //二进制传输数据
        //设置响应头
        response.setHeader("Content-Disposition",
                "attachment;fileName=" + URLEncoder.encode(fileName, "UTF-8"));

        File file = new File(path, fileName);
        //二、 读取文件--输入流
        InputStream input = new FileInputStream(file);
        //三、 写出文件--输出流
        OutputStream out = response.getOutputStream();

        byte[] buff = new byte[1024];
        int index = 0;
        //四、执行 写出操做
        while ((index = input.read(buff)) != -1) {
            out.write(buff, 0, index);
            out.flush();
        }
        out.close();
        input.close();
        return null;
    }