Springboot 文件上传、文件下载文件上传文件下载

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我是靠谱客的博主霸气帽子，这篇文章主要介绍Springboot 文件上传、文件下载文件上传文件下载，现在分享给大家，希望可以做个参考。

文件上传

controller层

使用 MultipartFile 类型接收单文件，多文件使用 MultipartFile[]
一般直接使用 @RequestParam("file") MultipartFile file 来接收
也可以在入参使用 MultipartHttpServletRequest ，后续使用 getFiles(参数名) 或 getFileMap() 方法获取到文件集合，再取出集合里的 MultipartFile (单个文件只取第一个)

注意：

必须使用 Post，且只能是 multipart/form-data 的方式，这是由传输机制导致的。不然服务器得不到上传的文件。GET方法是附加在URL后面的，而文件是二进制编码不能附加到 URL 后面 (上传的文件实际都是放在请求体里面的)
使用 @RequestParam 来限定参数名，@RequestParam 入参支持 Post 和 Get，是用来处理 ContentType 为 application/x-www-form-urlencoded（不指定时默认的）和 multipart/form-data 等格式的参数的。只有 application/json、application/xml 等格式的数据，才使用 @RequestBody 来处理。
可以看到 @RequestParam 实际是与 ContentType 挂钩的，而大多数时候如果接收是对象，忘记加注解，也可以接收到 application/x-www-form-urlencoded 的参数，这是因为 spring 默认对应了 @ModelAttribute 注解，等同于 @RequestParam 只不过参数是一个实体对象（两者也就是"MyOrder.orderAddress"和"orderAddress"的区别）。

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// 方式1
@PostMapping("/upload")
public Result<?> multiImport(@RequestParam("uploadFile") MultipartFile[] uploadFile) {
System.out.println(uploadFile.length);
for (MultipartFile multipartFile:uploadFile) {
// 文件名
multipartFile.getOriginalFilename());
// 获取文件
multipartFile.getInputStream();
}
return Result.ok();
}
// 方式2
@PostMapping("/upload")
public Result<?> importInfo(MultipartHttpServletRequest multipartRequest) {
Map<String, MultipartFile> fileMap = multipartRequest.getFileMap();
for (Map.Entry<String, MultipartFile> entity : fileMap.entrySet()) {
// 获取上传文件对象
MultipartFile file = entity.getValue();
// 获取文件
file.getInputStream();
...

Vue 前端

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<a href="https://file.download.com/huge.xlsx">
<a-button type="primary" icon="download" style="margin-left: 8px">导出模板</a-button>
</a>
<a-upload
style="margin-left: 8px"
@change="handleInfoImport"
:showUploadList="false"
:action="importInfo"
:headers="header">
<a-button type="primary" icon="upload">上传信息</a-button>
</a-upload>

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data() { return {
header: { 'X-Access-Token': Vue.ls.get(ACCESS_TOKEN) },
url: { importInfo: '/baseinfo/importInfo' }
}}
importInfo() { // 返回请求Url：服务器地址 + 请求API
return `${window._CONFIG['domianURL']}${this.url.importInfo}`
},
handleInfoImport(info) {
if (info.file.response.success) {
this.$message.info('信息导入成功，共导入' + info.file.response.result.total + '条')
} else {
this.$message.error(info.file.response.message)
}
}

普通Form表单提交

缺点：页面会刷新

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<form id="form111" enctype="multipart/form-data" method="post" action="#">
<!-- 可以选择多个文件，且只能选图片 -->
<input type="file" name="files" multiple id="test">
<input type="button" id="btn">
</form>

文件下载

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@RestController
@RequestMapping("/file")
public class FileResource {
@GetMapping("{name:.+}")
public void download(HttpServletResponse response, @PathVariable("name") String name) {
try {
Path path = Paths.get(name);
InputStream input;
if (!Files.exists(path)) {
// 拿到 resources 下文件 ClassPathXmlApplicationContext
ClassPathResource resource = new ClassPathResource(name);
if (!resource.exists()) throw new RuntimeException("文件不存在！");
input = resource.getInputStream();
} else {
input = Files.newInputStream(path);
response.setContentLength((int) Files.size(path));
}
//region response constructor
String mimeType = URLConnection.guessContentTypeFromName(name);
if (mimeType == null)
// unknown mimetype so set the mimetype to application/octet-stream
mimeType = "application/octet-stream";
response.setContentType(mimeType);
/*
In a regular HTTP response, the Content-Disposition response header is a header
indicating if the content is expected to be displayed inline in the browser, that is,
as a Web page or as part of a Web page, or as an attachment, that is downloaded and
saved locally.
Here we have mentioned it to show attachment
*/
response.setHeader(
"Content-Disposition",
"attachment; filename=" + URLEncoder.encode(name, "UTF-8"));
//endregion
StreamUtils.copy(input, response.getOutputStream());
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException("下载失败！" + e.getMessage());
}
}
}

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@RestController
@RequestMapping("/file")
public class FileResource {
@GetMapping("{name:.+}")
public void download(HttpServletResponse response, @PathVariable("name") String name) {
try {
Path path = Paths.get(name);
InputStream input;
if (!Files.exists(path)) {
// 拿到 resources 下文件 ClassPathXmlApplicationContext
ClassPathResource resource = new ClassPathResource(name);
if (!resource.exists()) throw new RuntimeException("文件不存在！");
input = resource.getInputStream();
} else {
input = Files.newInputStream(path);
response.setContentLength((int) Files.size(path));
}
//region response constructor
String mimeType = URLConnection.guessContentTypeFromName(name);
if (mimeType == null)
// unknown mimetype so set the mimetype to application/octet-stream
mimeType = "application/octet-stream";
response.setContentType(mimeType);
/*
In a regular HTTP response, the Content-Disposition response header is a header
indicating if the content is expected to be displayed inline in the browser, that is,
as a Web page or as part of a Web page, or as an attachment, that is downloaded and
saved locally.
Here we have mentioned it to show attachment
*/
response.setHeader(
"Content-Disposition",
"attachment; filename=" + URLEncoder.encode(name, "UTF-8"));
//endregion
StreamUtils.copy(input, response.getOutputStream());
} catch (Exception e) {
e.printStackTrace();
throw new RuntimeException("下载失败！" + e.getMessage());
}
}
}