SpringMVC下文件的上传与下载以及文件列表的显示

1、配置好SpringMVC环境-----SpringMVC的HelloWorld快速入门！

导入jar包：commons-fileupload-1.3.1.jar和commons-io-2.4.jar

文件上传和下载的jar包（百度云） ---> 资源目录--->jar包资源--->文件上传和下载的jar包

2、在SpringMVC配置文件springmvc.xml中配置CommonsMultipartResovler

<!-- 配置CommonsMultipartResolver -->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <property name="defaultEncoding" value="utf-8"></property>
    <!-- 以字节为单位 -->
    <property name="maxUploadSize" value="10485760"></property><!-- 1M=1024x1024 -->
</bean>

3、controller方法

@Controller
@RequestMapping("File")
public class FileController {
    //文件上传:表单：POST请求，file类型，enctype="multipart/form-data"
    @RequestMapping(value = "fileUpload", method = RequestMethod.POST)
    public String testUpload(HttpServletRequest request, @RequestParam(value = "desc", required = false) String desc,
            @RequestParam("photo") CommonsMultipartFile fileList[]) throws Exception {
        ServletContext servletContext = request.getServletContext();
        //获取服务器下的upload目录
        String realPath = servletContext.getRealPath("/upload");
        File filePath = new File(realPath);
        //如果目录不存在，则创建该目录
        if (!filePath.exists()) {
            filePath.mkdir();
        }
        OutputStream out;
        InputStream in;
        for (CommonsMultipartFile file : fileList) {
            if (file.getSize() == 0) {
                continue;
            }
            // 防止重命名uuid_name.jpg
            String prefix = UUID.randomUUID().toString();
            prefix = prefix.replace("-", "");
            String fileName = prefix + "_" + file.getOriginalFilename();
            out = new FileOutputStream(new File(realPath + "\\" + fileName));
            in = file.getInputStream();
            byte[] b = new byte[1024];
            int c = 0;
            while ((c = in.read(b)) != -1) {
                out.write(b, 0, c);
                out.flush();
            }
            out.close();
            in.close();
        }
        return "redirect:/File/showFile";
    }
    //用ResponseEntity<byte[]> 返回值完成文件下载
    @RequestMapping(value = "fileDownload")
    public ResponseEntity<byte[]> fileDownload(HttpServletRequest request, @RequestParam(value = "path") String path)
            throws Exception {
        byte[] body = null;
        // ServletContext servletContext = request.getServletContext();
        String fileName = path.substring(path.lastIndexOf("_") + 1); //从uuid_name.jpg中截取文件名
        // String path = servletContext.getRealPath("/WEB-INF/res/" + fileName);
        File file = new File(path);
        InputStream in = new FileInputStream(file);
        body = new byte[in.available()];
        in.read(body);
        HttpHeaders headers = new HttpHeaders();
        fileName = new String(fileName.getBytes("gbk"), "iso8859-1");
        headers.add("Content-Disposition", "attachment;filename=" + fileName);
        HttpStatus statusCode = HttpStatus.OK;
        ResponseEntity<byte[]> response = new ResponseEntity<byte[]>(body, headers, statusCode);
        in.close();
        return response;
    }
    //文件列表的显示
    @RequestMapping(value = "/showFile")
    public String showFile(HttpServletRequest request,Model m){
        ServletContext servletContext = request.getServletContext();
        String path=servletContext.getRealPath("/upload");
        File[] fileList = new File(path).listFiles();
        m.addAttribute("fileList", fileList);
        return "showFile";
    }
}

文件列表的显示没有对其进行处理，应该按时间排序：获取一个目录下的所有文件（按时间排序）

4、前台页面fileUpload.jsp和showFile.jsp

fileUpload.jsp

<form action="${pageContext.request.contextPath}/File/fileUpload"method="post" enctype="multipart/form-data">
    <input type="file" name="photo"><br>
    <input type="file" name="photo"><br>
    <input type="file" name="photo"><br>
    描述：<input type="text" name="desc"><br>
    <input type="submit" value="上传">
</form>

showFile.jsp

<c:choose>
    <c:when test="${not empty fileList }">
        <!--索引-->
        <c:set var="index" value='1'></c:set>
        <c:forEach items="${fileList }" var="file">
            <!-- filename:文件的名字，不带UUID -->
            <c:set var="filename" value='${fn:substring(file.name,fn:indexOf(file.name,"_")+1,fn:length(file.name)) }'/>
            <!-- filefullname:文件的名字，带UUID -->
            <c:set var="filefullname" value='${fn:split(file.path,"\\\\")[fn:length(fn:split(file.path,"\\\\"))-1] }'></c:set>
            <!-- rootdir:文件的目录 -->
            <c:set var="rootdir" value='${pageContext.request.contextPath}/upload/'></c:set>
            <div>
            <img alt='${fileanme }' src='${rootdir.concat(filefullname) }'><!-- 文件的全路径 -->
                <a href="${pageContext.request.contextPath}/File/fileDownload?path=${file.path}">下载</a>
            </div>
            <!-- 每行显示5张图片 -->
            <c:if test="${index%5==0 }">
                <br>
            </c:if>
            <!--索引+1-->
            <c:set var="index" value='${index+1 }'></c:set>
        </c:forEach>
    </c:when>
    <c:otherwise>
        暂无数据
    </c:otherwise>
</c:choose>

<c:set>中使用“\\”会报错，要使用“\\\\”，其他地方使用“\\”即可