spring boot實現文件上傳下載

時間 2019-11-17

原文原文鏈接

spring boot 引入」約定大於配置「的概念，實現自動配置，節約了開發人員的開發成本，而且憑藉其微服務架構的方式和較少的配置，一出來就佔據大片開發人員的芳心。大部分的配置從開發人員可見變成了相對透明瞭，要想進一步熟悉還須要關注源碼。
1.文件上傳(前端頁面)：html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">  
<html>  
<head>  
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">  
<title>Insert title here</title>  
</head>  
<body>  
<form action="/testUpload" method="POST" enctype="multipart/form-data">  
    <input type="file" name="file"/>  
    <input type="submit" />  
</form>  
<a href="/testDownload">下載</a>  
</body>  
</html>

表單提交加上enctype="multipart/form-data"很重要，文件以二進制流的形式傳輸。前端

2.文件上傳(後端java代碼)支持多文件java

Way1.使用MultipartHttpServletRequest來處理上傳請求，而後將接收到的文件以流的形式寫入到服務器文件中：web

@RequestMapping(value="/testUpload",method=RequestMethod.POST)  
    public void testUploadFile(HttpServletRequest req,MultipartHttpServletRequest multiReq) throws IOException{  
        FileOutputStream fos=new FileOutputStream(new File("F://test//src//file//upload.jpg"));  
        FileInputStream fs=(FileInputStream) multiReq.getFile("file").getInputStream();  
        byte[] buffer=new byte[1024];  
        int len=0;  
        while((len=fs.read(buffer))!=-1){  
            fos.write(buffer, 0, len);  
        }  
        fos.close();  
        fs.close();  
    }

Way2.也能夠這樣來取得上傳的file流：spring

// 文件上傳
    @RequestMapping("/fileUpload")
    public Map fileUpload(@RequestParam("file") MultipartFile file, HttpServletRequest req) {
        Map result = new HashMap();
        SimpleDateFormat df = new SimpleDateFormat("yyyyMMdd");// 設置日期格式
        String dateDir = df.format(new Date());// new Date()爲獲取當前系統時間
        String serviceName = UuidUtil.get32UUID()
                + file.getOriginalFilename().substring(file.getOriginalFilename().lastIndexOf("."));
        File tempFile = new File(fileDir + dateDir + File.separator + serviceName);
        if (!tempFile.getParentFile().exists()) {
            tempFile.getParentFile().mkdirs();
        }
        if (!file.isEmpty()) {
            try {
                BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(tempFile));
                // "d:/"+file.getOriginalFilename() 指定目錄
                out.write(file.getBytes());
                out.flush();
                out.close();
            } catch (FileNotFoundException e) {
                e.printStackTrace();
                result.put("msg", "上傳失敗," + e.getMessage());
                result.put("state", false);
                return result;
            } catch (IOException e) {
                e.printStackTrace();
                result.put("msg", "上傳失敗," + e.getMessage());
                result.put("state", false);
                return result;
            }
            result.put("msg", "上傳成功");
            String fileId = Get8uuid.generateShortUuid();
            String fileName = file.getOriginalFilename();
            String fileType = fileName.substring(fileName.lastIndexOf(".") + 1);
            String fileUrl = webDir + dateDir + '/' + serviceName;
            uploadMapper.saveFileInfo(fileId, serviceName, fileType, fileUrl);
            result.put("state", true);
            return result;
        } else {
            result.put("msg", "上傳失敗，由於文件是空的");
            result.put("state", false);
            return result;
        }

3.application.properties配置文件後端

#上傳文件大小設置
multipart.maxFileSize=500Mb
multipart.maxRequestSize=500Mb

4.文件下載將文件寫到輸出流裏：服務器

@RequestMapping(value="/testDownload",method=RequestMethod.GET)  
public void testDownload(HttpServletResponse res) throws IOException{  
  File file = new File("C:/test.txt");

　　resp.setHeader("content-type", "application/octet-stream");
　　resp.setContentType("application/octet-stream");
　　resp.setHeader("Content-Disposition", "attachment;filename=" + fileName);
　　byte[] buff = new byte[1024];
　　BufferedInputStream bis = null;
　　OutputStream os = null;
　　try {
　　os = resp.getOutputStream();
　　bis = new BufferedInputStream(new FileInputStream(file));
　　int i = bis.read(buff);
　　while (i != -1) {
　　os.write(buff, 0, buff.length);
　　os.flush();
　　i = bis.read(buff);
　　}
　　} catch (IOException e) {
　　e.printStackTrace();
　　} finally {
　　if (bis != null) {
　　try {
　　bis.close();
　　} catch (IOException e) {
　　e.printStackTrace();
　　}
　　}
}架構

} app

5.獲取文件大小微服務

// 文件大小轉換
DecimalFormat df1 = new DecimalFormat("0.00");
String fileSizeString = "";
long fileSize = file.getSize();
if (fileSize < 1024) {
    fileSizeString = df1.format((double) fileSize) + "B";
 } else if (fileSize < 1048576) {
    fileSizeString = df1.format((double) fileSize / 1024) + "K";
 } else if (fileSize < 1073741824) {
    fileSizeString = df1.format((double) fileSize / 1048576) + "M";
 } else {
    fileSizeString = df1.format((double) fileSize / 1073741824) + "G";
 }