Spring MVC 之文件上传与下载
上传文件
表单：
<form action="upload" enctype="multipart/form-data" method="post">
<input type="file" name="files" multiple/>
<input type="submit" value="Upload" />
</form>
表单的编码类型为multipart/form-data，表单中必须包含类型为file的元素，它会显示成一个按钮，点击时，打开一个对话框，用来选择文件。
如果上传多个文件，可添加multiple属性。
上传的文件会被包在一个MultipartFile对象中。
public interface MultipartFile extends InputStreamSource {
String getName();
@Nullable
String getOriginalFilename();
@Nullable
String getContentType();
boolean isEmpty();
long getSize();
byte[] getBytes() throws IOException;
@Override
InputStream getInputStream() throws IOException;
default Resource getResource() {
return new MultipartFileResource(this);
}
void transferTo(File dest) throws IOException, IllegalStateException;
default void transferTo(Path dest) throws IOException, IllegalStateException {
FileCopyUtils.copy(getInputStream(), Files.newOutputStream(dest));
}
}
控制器：
@RequestMapping("upload")
@ResponseBody
public String uploadFile (MultipartFile[] files, HttpServletRequest request)
throws IllegalStateException, IOException {
String path = request.getServletContext().getRealPath("/files");
for (MultipartFile file : files) {
String name = file.getOriginalFilename();
File f = new File(path, name);
file.transferTo(f);
}
return "fin";
}
配置：
<bean id="multipartResolver"
class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
<!-- 上传文件最大 10MB -->
<property name="maxUploadSize">
<value>10485760</value>
</property>
</bean>
依赖：commons-fileupload
下载文件
@RequestMapping("download")
public void downloadFile (@RequestParam String name, HttpServletRequest request, HttpServletResponse response)
throws IOException {
String path = request.getServletContext().getRealPath("/files");
File file = new File(path, name);
Path filepath = file.toPath();
response.setHeader("Content-Disposition", "attachment; filename=" + file.getName());
// response.setContentType
Files.copy(filepath, response.getOutputStream());
}
参考资料：《Spring MVC 学习指南》 Paul Deck 著