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How to use SpringBoot framework to receive multipart/form-data files

王林
Release: 2023-05-16 15:31:45
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SpringBoot框架接收multipart/form-data文件

现在很多文件上传类型都是multipart/form-data类型的,HTTP请求如下所示:

How to use SpringBoot framework to receive multipart/form-data files

可是问题就在于如果用传统的Struts2或者servlet等都可以很容易的实现文件接收的功能,例如下面的代码就可以实现:

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boolean isMultipart = ServletFileUpload.isMultipartContent(request);//判断是否是表单文件类型 

DiskFileItemFactory factory = new DiskFileItemFactory(); 

ServletFileUpload sfu = new ServletFileUpload(factory); 

List items = sfu.parseRequest(request);//从request得到所有上传域的列表 

for(Iterator iter = items.iterator();iter.hasNext();){ 

    FileItem fileitem =(FileItem) iter.next(); 

    if(!fileitem.isFormField()&&fileitem!=null){//判读不是普通表单域即是file 

        System.out.println("name:"+fileitem.getName()); 

    

}

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可是今天我把这一段代码放在SpringBoot上面的时候就怎么也接收不到文件信息了,一直以为是前端什么数据传输错了。后来才知道原来SpringBoot有它自己的接收请求的代码。下面就给大家详细介绍一下它是如何实现这个功能的。

首选做一个简单的案例,也就是单个文件上传的案例。为了进行这个案例,首先需要建立一个SpringBoot框架

前台HTML代码:

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<html> 

<body> 

  <form action="/upload" method="POST" enctype="multipart/form-data"

    <input type="file" name="file"/> 

    <input type="submit" value="Upload"/>  

  </form> 

</body> 

</html>

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How to use SpringBoot framework to receive multipart/form-data files

后台接收代码:

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/**  

     * 文件上传具体实现方法;  

     *   

     * @param file  

     * @return  

     */   

    @RequestMapping("/upload")   

    @ResponseBody   

    public String handleFileUpload(@RequestParam("file") MultipartFile file) {   

        if (!file.isEmpty()) {   

            try {   

                /*  

                 * 这段代码执行完毕之后,图片上传到了工程的跟路径; 大家自己扩散下思维,如果我们想把图片上传到  

                 * d:/files大家是否能实现呢? 等等;  

                 * 这里只是简单一个例子,请自行参考,融入到实际中可能需要大家自己做一些思考,比如: 1、文件路径; 2、文件名;  

                 * 3、文件格式; 4、文件大小的限制;  

                 */   

                BufferedOutputStream out = new BufferedOutputStream(   

                        new FileOutputStream(new File(   

                                file.getOriginalFilename())));   

                System.out.println(file.getName()); 

                out.write(file.getBytes());   

                out.flush();   

                out.close();   

            } catch (FileNotFoundException e) {   

                e.printStackTrace();   

                return "上传失败," + e.getMessage();   

            } catch (IOException e) {   

                e.printStackTrace();   

                return "上传失败," + e.getMessage();   

            }   

     

            return "上传成功";   

     

        } else {   

            return "上传失败,因为文件是空的.";   

        }   

    }

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这样便可以接收multipart/form-data类型的文件。接下来,我们来看一个上传多个文件并且每个文件都有多个字段的案例。

前台HTML界面:

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<!DOCTYPE html>   

<html xmlns="http://www.w3.org/1999/xhtml" xmlns:th="http://www.thymeleaf.org"   

      xmlns:sec="http://www.thymeleaf.org/thymeleaf-extras-springsecurity3">   

    <head>   

        <title>Hello World!</title>   

    </head>   

    <body>   

       <form method="POST" enctype="multipart/form-data" action="/batch/upload">    

           <p>文件1:<input type="text" name="id" /></p>   

           <p>文件2:<input type="text" name="name" /></p>   

           <p>文件3:<input type="file" name="file" /></p>   

           <p><input type="submit" value="上传" /></p>   

       </form>   

    </body>   

</html>

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How to use SpringBoot framework to receive multipart/form-data files

后台接收代码:

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@RequestMapping(value = "/batch/upload", method = RequestMethod.POST)   

      @ResponseBody   

      public String handleFileUpload(HttpServletRequest request) {   

        MultipartHttpServletRequest params=((MultipartHttpServletRequest) request); 

          List<MultipartFile> files = ((MultipartHttpServletRequest) request)   

                  .getFiles("file");  

          String name=params.getParameter("name"); 

          System.out.println("name:"+name); 

          String id=params.getParameter("id"); 

          System.out.println("id:"+id); 

          MultipartFile file = null;   

          BufferedOutputStream stream = null;   

          for (int i = 0; i < files.size(); ++i) {   

              file = files.get(i);   

              if (!file.isEmpty()) {   

                  try {   

                      byte[] bytes = file.getBytes();   

                      stream = new BufferedOutputStream(new FileOutputStream(   

                              new File(file.getOriginalFilename())));   

                      stream.write(bytes);   

                      stream.close();   

                  } catch (Exception e) {   

                      stream = null;   

                      return "You failed to upload " + i + " => "   

                              + e.getMessage(); 

                  }   

              } else {   

                  return "You failed to upload " + i   

                          + " because the file was empty.";   

              

          }   

          return "upload successful"

      }

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这样就可以实现对多个文件的接收了功能了。

SpringBoot还可以对接收文件的格式还有个数等等进行限制,我这里就不多说了,大家有兴趣的可以自己去了解了解。

千万要记住SpringBoot对multipart/form-data类型的文件接收和其它是不一样的,大家以后遇到的时候要千万小心,不要像我一样一往无前的踩进去还傻傻的以为是前端的错误。

SpringBoot接收文件

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package cn.juhe.controller;

  

import net.sf.json.JSONObject;

import org.springframework.web.bind.annotation.PostMapping;

import org.springframework.web.bind.annotation.RequestParam;

import org.springframework.web.bind.annotation.RestController;

import org.springframework.web.multipart.MultipartFile;

import org.springframework.web.multipart.MultipartHttpServletRequest;

  

import javax.servlet.http.HttpServletRequest;

import java.io.BufferedOutputStream;

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.util.Date;

import java.util.Iterator;

import java.util.List;

import java.util.Random;

  

@RestController

public class UploadTest {

    /**

     * 接受未知参数名的多个文件或者一个文件

     *

     * @param request 请求

     * @return 返回

     */

    @PostMapping("/upload")

    public JSONObject handleFileUpload(HttpServletRequest request) {

        Iterator<String> fileNames = ((MultipartHttpServletRequest) request).getFileNames();

        JSONObject result = null;

        while (fileNames.hasNext()) {

            String next = fileNames.next();

            MultipartFile file = ((MultipartHttpServletRequest) request).getFile(next);

            System.out.println("file.getName():" + file.getName());

            System.out.println("file.getOriginalFilename():" + file.getOriginalFilename());

            String folder = "E:\\upload\\received\\";

            String picName = new Date().getTime() + ".jpg";

            File filelocal = new File(folder, picName);

            result = new JSONObject();

            result.put(picName, folder + picName);

            try {

                file.transferTo(filelocal);

            } catch (IOException e) {

                e.printStackTrace();

            }

        }

        JSONObject jsonObject = new JSONObject();

        jsonObject.put("error_code", 223805);

        jsonObject.put("reason", "文件过大或上传发生错误");

        Random random = new Random();

        if (random.nextInt(10) > 3) {

            jsonObject.put("error_code", 0);

            jsonObject.put("reason", "success");

  

            jsonObject.put("result", result);

        }

        return jsonObject;

    }

  

    /**

     * 知道参数名的文件上传

     *

     * @param multipartFile 文件

     * @return 返回

     * @throws IOException

     */

    @PostMapping("/uploadCommon")

    //public JSONObject upload(MultipartFile multipartFile) throws IOException {

    public JSONObject upload(@RequestParam("A") MultipartFile multipartFile) throws IOException {

        String name = multipartFile.getName();//上传文件的参数名

        String originalFilename = multipartFile.getOriginalFilename();//上传文件的文件路径名

        long size = multipartFile.getSize();//文件大小

        String folder = "E:\\upload\\received\\";

        String picName = new Date().getTime() + ".jpg";

        File filelocal = new File(folder, picName);

        multipartFile.transferTo(filelocal);

       /* {

            "reason": "success",

                "result": {

            "D": "/upload/order/files/2016/a72750ad-8950-4949-b04a-37e69aff0d23.jpg",

                    "A": "/upload/order/files/2016/6842811a-eb76-453b-a2f3-488e2bb4500e.jpg",

                    "B": "/upload/order/files/2016/ccc96347-3cb8-4e2e-99a3-0c697b57eb88.jpg",

                    "C": "/upload/order/files/2016/d470d533-a54b-406a-a0f9-bbf82c314755.jpg"

        },

            "error_code": 0

        }*/

        JSONObject jsonObject = new JSONObject();

        jsonObject.put("error_code", 223805);

        jsonObject.put("reason", "文件过大或上传发生错误");

        Random random = new Random();

        if (random.nextInt(10) > 3) {

            jsonObject.put("error_code", 0);

            jsonObject.put("reason", "success");

            JSONObject result = new JSONObject();

            result.put(name, folder + picName);

            jsonObject.put("result", result);

        }

        return jsonObject;

    }

}

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