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