sprintboot+scala文件上传下载

常用的springboot+scala实现的webservice上传下载，

maven配置文件采用常规配置，见springboot+scala配置

后端代码

FileController.scala

package org.tashaxing.controller

import java.io._

import org.springframework.web.bind.annotation._
import org.springframework.core.io.{InputStreamResource, Resource}
import org.springframework.http.ResponseEntity
import org.springframework.http.HttpHeaders
import org.springframework.http.HttpStatus
import org.springframework.http.MediaType
import org.springframework.web.multipart.MultipartFile


@RestController
@RequestMapping(Array("/api"))
class FileController
{
    @PostMapping(Array("/file/upload/{myparam}"))
    def uploadFile(@PathVariable(value = "myparam") myparam: String,  // extra param submitted
                   @RequestBody file: MultipartFile): Boolean =
    {
        if (file.isEmpty)
            return false

        val filename = file.getOriginalFilename
        val suffix = filename.substring(filename.lastIndexOf('.'))

        // save to directory
        
        // here do sth to handle the file record, maybe insert record to database

        val save_dir = "D:/file"  // absolute and relative path are both OK
        val save_file = new File(save_dir + '/' + filename) // we can customize the filename, make sure the suffix is right

        file.transferTo(save_file) // save to file system

        return true
    }

    @PostMapping(Array("/file/delete/{filename}"))
    def deleteReceipt(@PathVariable(value = "filename") filename: String): Boolean =
    {
        // first maybe delete record from database

        // delete from file system
        val file_dir = "D:/file" // absolute and relative path are both OK
        val file = new File(file_dir + '/' + filename)
        if (file.exists())
            file.delete()

        return true
    }

    @GetMapping(Array("/file/download/{filename}"))
    def downloadReceipt(@PathVariable(value = "filename") filename: String): ResponseEntity[Resource] =
    {
        // just support download pdf for this demo
        val headers = new HttpHeaders
        headers.setContentType(MediaType.parseMediaType("application/pdf")) // maybe other format: application/png 
        val file = new File(FbConfig.file_root + '/' + filename)
        val resource = new InputStreamResource(new FileInputStream(file))

        return ResponseEntity.ok()
            .headers(headers)
            .contentLength(file.length())
            .contentType(MediaType.parseMediaType("application/pdf"))
            .body(resource)
    }
}

前端代码

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <title>Getting Started: Serving Web Content</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
</head>
<body>
<p>Get your greeting <a href="/greeting">here</a></p>
<form action="/upload" method="POST" enctype="multipart/form-data">
    文件：<input type="file" name="file"/>
    <input type="submit" />
</form>
<a href="/download">下载</a>
</html>

这样就简单实现了一个上传下载功能，需要注意的是

前端的input空间里面name要和后端的upload函数里面的参数对应，如：“file”
前端可以用react之类的框架包装，但是写法基本一致，上传用表单，下载用href链接
如果要支持多种文件格式，后端基本不用改，只要在下载的函数里面改一下文件格式
需要在springboot的配置文件里面指定上传下载的文件大小上限

sprintboot+scala文件上传下载

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