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Live-Server-8-SpringBoot文件上传下载

服务器中的文件上传下载是基本操作，图片、用户头像的上传下载、文件的传输和资源分享等已经成为每个应用必不可少的功能。在我的认知中，服务器的文件存储下载简单流程是这样的：上传文件->在数据库中记录该文件的相关信息（文件名、大小、路径等）->提供文件列表->文件下载。

由于项目中只有App增量更新需要上传和下载文件，那么这里就将文件的路径固定。

上传下载页面：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8"></meta>
    <title>文件上传</title>
</head>
<body>
<p>单文件上传</p>
<form action="upload" method="POST" enctype="multipart/form-data">
    文件：<input type="file" name="file"/>
    <input type="submit"/>
</form>
<hr/>
<p>文件下载</p>
<a href="download">下载最新安装包</a>
<hr/>
<p>多文件上传</p>
<form method="POST" enctype="multipart/form-data" action="batch">
    <p>文件1：<input type="file" name="file"/></p>
    <p>文件2：<input type="file" name="file"/></p>
    <p><input type="submit" value="上传"/></p>
</form>
</body>
</html>
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上传和下载控制器：

@RestController
public class FileController {
    private static final Logger log = LoggerFactory.getLogger(FileController.class);

    @Autowired
    private VersionService versionService;

    @RequestMapping(value = "/upload")
    public String upload(@RequestParam("file") MultipartFile file) {
        try {
            if (file.isEmpty()) {
                return "文件为空";
            }
            //获取文件名
            String fileName = file.getOriginalFilename();
            log.debug("上传的文件名字：" + fileName);
            //获取文件的后缀名
            String suffixName = fileName.substring(fileName.lastIndexOf("."));
            log.debug("文件的后缀名为：" + suffixName);
            // 设置文件存储路径
            String filePath = "/usr/local/download/";
            String path = filePath + fileName;
            File dest = new File(path);
            // 检测是否存在目录
            if (!dest.getParentFile().exists()) {
                dest.getParentFile().mkdirs();// 新建文件夹
            }
            file.transferTo(dest);// 文件写入
            return "上传成功";
        } catch (IllegalStateException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return "上传失败";
    }

    @PostMapping("/batch")
    public String handleFileUpload(HttpServletRequest request) {
        List<MultipartFile> files = ((MultipartHttpServletRequest) request).getFiles("file");
        MultipartFile file = null;
        BufferedOutputStream stream = null;
        for (int i = 0; i < files.size(); ++i) {
            file = files.get(i);
            String filePath = "/usr/local/download/";
            if (!file.isEmpty()) {
                try {
                    byte[] bytes = file.getBytes();
                    stream = new BufferedOutputStream(new FileOutputStream(
                            new File(filePath + file.getOriginalFilename())));//设置文件路径及名字
                    stream.write(bytes);// 写入
                    stream.close();
                } catch (Exception e) {
                    stream = null;
                    return "第 " + i + " 个文件上传失败 ==> "
                            + e.getMessage();
                }
            } else {
                return "第 " + i
                        + " 个文件上传失败因为文件为空";
            }
        }
        return "上传成功";
    }

    @GetMapping("download")
    public String downloadFile(HttpServletRequest request, HttpServletResponse response) {
        String fileName = "app_new.apk";
        if (fileName != null) {
            //设置文件路径
            File file = new File("/usr/local/live/download/" + fileName);
            if (file.exists()) {
                response.setContentType("application/force-download"); //设置强制下载不打开
                //设置文件名
                response.addHeader("Content-Disposition", "attachment;fileName=" + fileName);
                byte[] buffer = new byte[1024];
                FileInputStream fis = null;
                BufferedInputStream bis = null;
                try {
                    fis = new FileInputStream(file);
                    bis = new BufferedInputStream(fis);
                    OutputStream os = response.getOutputStream();
                    int i = bis.read(buffer);
                    while (i != -1) {
                        os.write(buffer, 0, i);
                        i = bis.read(buffer);
                    }
                    return "下载成功";
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    if (bis != null) {
                        try {
                            bis.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                    if (fis != null) {
                        try {
                            fis.close();
                        } catch (IOException e) {
                            e.printStackTrace();
                        }
                    }
                }
            }
        }
        return "下载失败";
    }
}
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原文 https://juejin.im/post/5d5d3cc26fb9a06ae7640bf6

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