这篇文章主要介绍了java实现文件上传下载功能，上传单个或多个文件，文中示例代码介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们可以参考一下
本文实例为大家分享了java实现文件上传下载的具体代码，供大家参考，具体内容如下
1.上传单个文件
Controller控制层
import java.io.File; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod;<p style="color:transparent">来源gao!daima.com搞$代!码网</p> import org.springframework.web.bind.annotation.RequestParam; import org.springframework.web.multipart.MultipartFile; import org.springframework.web.servlet.mvc.support.RedirectAttributes; @Controller @RequestMapping("testup") public class UploadController { private static Logger LG= LoggerFactory.getLogger(UploadController.class); /** * 9.①单个文件上传 * @param file * @param redirectAttributes * @return */ @RequestMapping(value="/upload",method=RequestMethod.POST,consumes="multipart/form-data") public String uploadFile(@RequestParam MultipartFile file,RedirectAttributes redirectAttributes){ if(file.isEmpty()){ redirectAttributes.addFlashAttribute("message", "Plse select file"); return "redirect:/test/index"; } try { String fileName=file.getOriginalFilename(); /*上传文件存储位置*/ String destFileName="D:\\whupload"+File.separator+fileName; File destFile=new File(destFileName); file.transferTo(destFile); //文件上传成功显示 //redirectAttributes.addAttribute("message","upload file success."); redirectAttributes.addFlashAttribute("message", "upload file success."); } catch (Exception e) { //文件上传失败显示 redirectAttributes.addFlashAttribute("message", "upload file fail"); LG.debug(e.getMessage()); } return "redirect:/test/index"; } }
前端页面源码
<p>上传文件，使用multipart/form-data类型</p> <button type="submit">上传</button>
2.上传多个文件
Controller控制层
import java.io.File; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import org.springframework.web.bind.annotation.RequestParam; import org.springframework.web.multipart.MultipartFile; import org.springframework.web.servlet.mvc.support.RedirectAttributes; @Controller @RequestMapping("testup") public class UploadController { private static Logger LG= LoggerFactory.getLogger(UploadController.class); /** * 9.②多个文件上传 */ @RequestMapping(value="/uploadBatchFile",method=RequestMethod.POST,consumes="multipart/form-data") public String uploadBatchFile(@RequestParam MultipartFile[] files,RedirectAttributes redirectAttributes){ boolean isEmpty=true; try { for (MultipartFile multipartFile : files) { if(multipartFile.isEmpty()){ continue; } String fileName=multipartFile.getOriginalFilename(); String destFileName="D:\\whupload"+File.separator+fileName; File destFile=new File(destFileName); multipartFile.transferTo(destFile); isEmpty=false; } //int i=1/0; //localhost:8086/test/index?message=upload file success //redirectAttributes.addAttribute("message","upload file success."); } catch (Exception e) { // TODO Auto-generated catch block redirectAttributes.addFlashAttribute("message", "upload file fail"); LG.debug(e.getMessage()); return "redirect:/test/index"; } if(isEmpty){ redirectAttributes.addFlashAttribute("message", "Plse select file"); }else{ redirectAttributes.addFlashAttribute("message", "upload file success."); } return "redirect:/test/index"; } }
前端页面源码
<button type="submit">上传</button>
3.下载文件
Controller控制器
import java.io.File; import java.net.MalformedURLException; import java.nio.file.Paths; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.core.io.Resource; import org.springframework.core.io.UrlResource; import org.springframework.http.HttpHeaders; import org.springframework.http.ResponseEntity; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestParam; import org.springframework.web.bind.annotation.ResponseBody; @Controller @RequestMapping("testup") public class UploadController { private static Logger LG= LoggerFactory.getLogger(UploadController.class); /** * 10.下载文件 */ @RequestMapping("/download") @ResponseBody public ResponseEntity downloadFile(@RequestParam String fileName){ try { Resource resource=new UrlResource( //拼接下载的文件的原路径 Paths.get("D:/whupload"+File.separator+fileName).toUri()); if(resource.exists() && resource.isReadable()){ return ResponseEntity.ok() .header(HttpHeaders.CONTENT_TYPE, "application/octet-stream") .header(HttpHeaders.CONTENT_DISPOSITION,"attachment;filename=\""+ resource.getFilename()+"\"").body(resource); } } catch (MalformedURLException e) { // TODO Auto-generated catch block e.printStackTrace(); LG.debug(e.getMessage()); } return null; } }
前端页面源码
<p>下载文件，这里设置默认下载文件为Demo.txt,fileName是下载文件名</p>download file
运行效果
最后，需要注意的是，文件上传有默认的大小限制
在配置文件中加入，即可消除限制
spring.servlet.multipart.max-file-size=-1 spring.servlet.multipart.max-request-size=-1
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