java实现文件上传下载功能

java实现文件上传下载功能

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;

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

上传文件，使用multipart/form-data类型

上传

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;

imImWfwxeport 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

上传

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

下载文件，这里设置默认下载文件为Demo.txt,fileName是下载文件名

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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