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java實現(xiàn)文件上傳下載功能

更新時間：2021年08月26日 10:20:10 作者：wh456413

這篇文章主要介紹了java實現(xiàn)文件上傳下載功能，上傳單個或多個文件，文中示例代碼介紹的非常詳細(xì)，具有一定的參考價值，感興趣的小伙伴們可以參考一下

本文實例為大家分享了java實現(xiàn)文件上傳下載的具體代碼，供大家參考，具體內(nèi)容如下

1.上傳單個文件

Controller控制層

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單個文件上傳
     * @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();
            /*上傳文件存儲位置*/
            String destFileName="D:\\whupload"+File.separator+fileName;
            File destFile=new File(destFileName);
            file.transferTo(destFile);
            //文件上傳成功顯示
            //redirectAttributes.addAttribute("message","upload file success.");
            redirectAttributes.addFlashAttribute("message", "upload file success.");
        } catch (Exception e) {
            //文件上傳失敗顯示
            redirectAttributes.addFlashAttribute("message", "upload file fail");
            LG.debug(e.getMessage());
        }
        return "redirect:/test/index";
    }

}

前端頁面源碼

<p>上傳文件，使用multipart/form-data類型</p>
  <form action="/testup/upload" method="post" enctype="multipart/form-data">
        <input type="file" name="file">
        <button type="submit">上傳</button>
</form>

2.上傳多個文件

Controller控制層

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多個文件上傳
     */
    @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";
    }

    
}

前端頁面源碼

<form action="/testup/uploadBatchFile" method="post" enctype="multipart/form-data">
        <input type="file" name="files">
        <input type="file" name="files">
        <button type="submit">上傳</button>
</form>

3.下載文件

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.下載文件
     */
    @RequestMapping("/download")
    @ResponseBody
    public ResponseEntity<Resource> downloadFile(@RequestParam String fileName){
        try {
            Resource resource=new UrlResource(
                    //拼接下載的文件的原路徑
                    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;
    }
}

前端頁面源碼

<p>下載文件，這里設(shè)置默認(rèn)下載文件為Demo.txt,fileName是下載文件名</p>
<a href="/testup/download?fileName=Demo.txt" rel="external nofollow" >download file</a>

運行效果

最后，需要注意的是，文件上傳有默認(rèn)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

以上就是本文的全部內(nèi)容，希望對大家的學(xué)習(xí)有所幫助，也希望大家多多支持腳本之家。

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java實現(xiàn)文件上傳下載功能

1.上傳單個文件

2.上傳多個文件

3.下載文件

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