SpringMVC——实现文件上传下载
参考：
http://blog.csdn.net/u012706811/article/details/51059419
http://blog.csdn.net/u012660464/article/details/53434331
一、文件上传
1.引入依赖包
在pom.xml文件中添加如下内容，引入 commons-fileupload 和 commons-io 两个包。
<dependency>
<groupId>commons-fileuploadgroupId>
<artifactId>commons-fileuploadartifactId>
<version>1.3.1version>
dependency>
<dependency>
<groupId>commons-iogroupId>
<artifactId>commons-ioartifactId>
<version>2.3version>
dependency>2.spring-mvc.xml
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<property name="maxUploadSize" value="1048576" />
bean>3.fileUpload.jsp
form中加入 enctype=”multipart/form-data” 属性，表示将文件一二进制流传输，否则报错。
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>fileUpload —— 单个文件title>
head>
<body>
<h1 align = "center">文件上传h1>
<form action = "${website}FileController" enctype="multipart/form-data" method = "post">
选择文件:<input type="file" name = "file">
<input type="submit" value = "提交">
form>
body>
html>4.Success.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>successtitle>
head>
<body>
<h1 align="center">Success!h1>
body>
html>
5.index.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<body>
<h2 align="center">Hello World!h2>
<a href="${website}admin/listUser">进入用户管理界面a>
<a href="${website}file/fileUpload">上传单个文件a>
<a href="${website}file/multiFileUpload">上传多个文件a>
<%--"${website}file/fileDownload">下载文件--%>
<a href="${website}file/download">下载指定文件a>
body>
html>
6.FileController
/**
* 去文件上传页面
*
* @return
*/
@RequestMapping(value = "fileUpload", method = RequestMethod.GET)
public String toFileUpload(){
return "/file/fileUpload";
}
/**
* 单个文件上传
*
* @param file
* @return
*/
@RequestMapping(value = "upload", method = RequestMethod.POST)
public String fileUpload(@RequestParam("file")MultipartFile file){
if (!file.isEmpty()){
try {
//存入F:\temp目录下
FileUtils.copyInputStreamToFile(file.getInputStream(), new File("F:\\temp",
System.currentTimeMillis()+ file.getOriginalFilename()));
} catch (IOException e){
e.printStackTrace();
}
}
//上传成功，跳转至success页面
return "file/success";
}
7.多个文件上传
/**
* 去多个文件上传页面
*
* @return
*/
@RequestMapping(value = "multiFileUpload", method = RequestMethod.GET)
public String toMultiFileUpload(){
return "/file/multiFileUpload";
}
/**
* 多个文件上传
*
* @param multiRequest
* @return
*/
@RequestMapping(value = "multiUpload", method = RequestMethod.POST)
public String multiFileUpload(MultipartHttpServletRequest multiRequest) throws IOException {
Iterator filesNames = multiRequest.getFileNames(); //获得所有的文件名
while(filesNames.hasNext()){ //迭代，对单个文件进行操作
String fileName =filesNames.next();
MultipartFile file = multiRequest.getFile(fileName);
if(!file.isEmpty()){
FileUtils.copyInputStreamToFile(file.getInputStream(), new File("F:\\temp",
System.currentTimeMillis()+ file.getOriginalFilename()));
}
}
//上传成功，跳转至success页面
return "file/success";
} 
二、文件下载
1.index.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<body>
<h2 align="center">Hello World!h2>
<a href="${website}admin/listUser">进入用户管理界面a>
<a href="${website}file/fileUpload">上传文件a>
<%--"${website}file/fileDownload">下载文件--%>
<a href="${website}file/download">下载指定文件a>
body>
html>
2.FileController
现在实现的功能是点击“下载指定文件”则下载在controller中指定好的文件，还没有实现把上传的文件传入数据库，也没实现下载数据库中要存的文件，日后慢慢改进。
/**
* 指定文件下载
*
* @return
* @throws IOException
*/
@RequestMapping(value = "download",produces = "application/octet-stream;charset=UTF-8")
public ResponseEntity<byte[]> download() throws IOException {
// 指定文件,必须是绝对路径
File file = new File("F:\\temp\\1513489657107psb.jpg");
// 下载浏览器响应的那个文件名
String dfileName = "1.jpg";
// 下面开始设置HttpHeaders,使得浏览器响应下载
HttpHeaders headers = new HttpHeaders();
// 设置响应方式
headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
// 设置响应文件
headers.setContentDispositionFormData("attachment", dfileName);
// 把文件以二进制形式写回
return new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(file), headers, HttpStatus.CREATED);
}效果
