1、yml配置

file:
    domain: http://172.11.1.1:9300(服务器ip:端口)
    path: /home/admin/test(文件在linux的存放地址)
    prefix: /statics

2、java获取到yml配置数据

     //资源映射路径 前缀
    @Value("${file.prefix}")
    public String localFilePrefix;
    
     //域名或本机访问地址
    @Value("${file.domain}")
    public String domain;
    
   //上传文件存储在本地的根路径
    @Value("${file.path}")
    private String localFilePath;

3、文件上传请求

/**
     * 文件上传请求
     */
    @PostMapping("/upload")
    public R<List<SysFile>> upload(@RequestParam(name = "file", required = false) List<MultipartFile> files) {
        try {
            List<SysFile> list = new ArrayList<>();
            for (MultipartFile file : files) {
                // 上传并返回访问地址
                String url = sysFileService.uploadFile(file);
                String originalFilename = file.getOriginalFilename();
                SysFile sysFile = new SysFile();
                sysFile.setName(FileUtils.getName(url));
                sysFile.setOriginalAttachmentName(originalFilename);
                sysFile.setUrl(url);
                sysFile.setDate(new Date());
                list.add(sysFile);
            }
            return R.ok(list);
        } catch (Exception e) {
            log.error("上传文件失败", e);
            return R.fail(e.getMessage());
        }
    }

/**
     * 本地文件上传接口
     * 
     * @param file 上传的文件
     * @return 访问地址
     * @throws Exception
     */
    @Override
    public String uploadFile(MultipartFile file) throws Exception
    {
        String name = FileUploadUtils.upload(localFilePath, file);
        String url = domain + localFilePrefix + name;
        return url;
    }

package com.xinruan.file.utils;

import java.io.File;
import java.io.IOException;
import java.nio.file.Paths;
import java.util.Objects;
import org.apache.commons.io.FilenameUtils;
import org.springframework.web.multipart.MultipartFile;
import com.xinruan.common.core.exception.file.FileNameLengthLimitExceededException;
import com.xinruan.common.core.exception.file.FileSizeLimitExceededException;
import com.xinruan.common.core.exception.file.InvalidExtensionException;
import com.xinruan.common.core.utils.DateUtils;
import com.xinruan.common.core.utils.StringUtils;
import com.xinruan.common.core.utils.file.MimeTypeUtils;
import com.xinruan.common.core.utils.uuid.Seq;

/**
 * 文件上传工具类
 * 
 * @author ruoyi
 */
public class FileUploadUtils
{
    /**
     * 默认大小 50M
     */
    public static final long DEFAULT_MAX_SIZE = 50 * 1024 * 1024;

    /**
     * 默认的文件名最大长度 100
     */
    public static final int DEFAULT_FILE_NAME_LENGTH = 100;

    /**
     * 根据文件路径上传
     *
     * @param baseDir 相对应用的基目录
     * @param file 上传的文件
     * @return 文件名称
     * @throws IOException
     */
    public static final String upload(String baseDir, MultipartFile file) throws IOException
    {
        try
        {
            return upload(baseDir, file, MimeTypeUtils.DEFAULT_ALLOWED_EXTENSION);
        }
        catch (Exception e)
        {
            throw new IOException(e.getMessage(), e);
        }
    }

    /**
     * 文件上传
     *
     * @param baseDir 相对应用的基目录
     * @param file 上传的文件
     * @param allowedExtension 上传文件类型
     * @return 返回上传成功的文件名
     * @throws FileSizeLimitExceededException 如果超出最大大小
     * @throws FileNameLengthLimitExceededException 文件名太长
     * @throws IOException 比如读写文件出错时
     * @throws InvalidExtensionException 文件校验异常
     */
    public static final String upload(String baseDir, MultipartFile file, String[] allowedExtension)
            throws FileSizeLimitExceededException, IOException, FileNameLengthLimitExceededException,
            InvalidExtensionException
    {
        int fileNamelength = Objects.requireNonNull(file.getOriginalFilename()).length();
        if (fileNamelength > FileUploadUtils.DEFAULT_FILE_NAME_LENGTH)
        {
            throw new FileNameLengthLimitExceededException(FileUploadUtils.DEFAULT_FILE_NAME_LENGTH);
        }

        assertAllowed(file, allowedExtension);//文件大小校验和文件类型是否满足上传要求校验

        String fileName = extractFilename(file);

        String absPath = getAbsoluteFile(baseDir, fileName).getAbsolutePath();
        file.transferTo(Paths.get(absPath));
        return getPathFileName(fileName);
    }

    /**
     * 编码文件名
     */
    public static final String extractFilename(MultipartFile file)
    {
//        return StringUtils.format("{}/{}_{}.{}", DateUtils.datePath(),
//            FilenameUtils.getBaseName(file.getOriginalFilename()), Seq.getId(Seq.uploadSeqType), getExtension(file));
        return StringUtils.format("{}/{}.{}", DateUtils.datePath(),Seq.getId(Seq.uploadSeqType), getExtension(file));
    }

    private static final File getAbsoluteFile(String uploadDir, String fileName) throws IOException
    {
        File desc = new File(uploadDir + File.separator + fileName);

        if (!desc.exists())
        {
            if (!desc.getParentFile().exists())
            {
                desc.getParentFile().mkdirs();
            }
        }
        return desc.isAbsolute() ? desc : desc.getAbsoluteFile();
    }

    private static final String getPathFileName(String fileName) throws IOException
    {
        String pathFileName = "/" + fileName;
        return pathFileName;
    }

    /**
     * 文件大小校验
     *
     * @param file 上传的文件
     * @throws FileSizeLimitExceededException 如果超出最大大小
     * @throws InvalidExtensionException 文件校验异常
     */
    public static final void assertAllowed(MultipartFile file, String[] allowedExtension)
            throws FileSizeLimitExceededException, InvalidExtensionException
    {
        long size = file.getSize();
        if (size > DEFAULT_MAX_SIZE)
        {
            throw new FileSizeLimitExceededException(DEFAULT_MAX_SIZE / 1024 / 1024);
        }

        String fileName = file.getOriginalFilename();
        String extension = getExtension(file);//获取文件名的后缀
        if (allowedExtension != null && !isAllowedExtension(extension, allowedExtension))//判断上传的文件后缀是否满足要求
        {
            if (allowedExtension == MimeTypeUtils.IMAGE_EXTENSION)
            {
                throw new InvalidExtensionException.InvalidImageExtensionException(allowedExtension, extension,
                        fileName);
            }
            else if (allowedExtension == MimeTypeUtils.FLASH_EXTENSION)
            {
                throw new InvalidExtensionException.InvalidFlashExtensionException(allowedExtension, extension,
                        fileName);
            }
            else if (allowedExtension == MimeTypeUtils.MEDIA_EXTENSION)
            {
                throw new InvalidExtensionException.InvalidMediaExtensionException(allowedExtension, extension,
                        fileName);
            }
            else if (allowedExtension == MimeTypeUtils.VIDEO_EXTENSION)
            {
                throw new InvalidExtensionException.InvalidVideoExtensionException(allowedExtension, extension,
                        fileName);
            }
            else
            {
                throw new InvalidExtensionException(allowedExtension, extension, fileName);
            }
        }
    }

    /**
     * 判断MIME类型是否是允许的MIME类型
     *
     * @param extension 上传文件类型
     * @param allowedExtension 允许上传文件类型
     * @return true/false
     */
    public static final boolean isAllowedExtension(String extension, String[] allowedExtension)
    {
        for (String str : allowedExtension)
        {
            if (str.equalsIgnoreCase(extension))
            {
                return true;
            }
        }
        return false;
    }

    /**
     * 获取文件名的后缀
     * 
     * @param file 表单文件
     * @return 后缀名
     */
    public static final String getExtension(MultipartFile file)
    {
        String extension = FilenameUtils.getExtension(file.getOriginalFilename());
        if (StringUtils.isEmpty(extension))
        {
            extension = MimeTypeUtils.getExtension(Objects.requireNonNull(file.getContentType()));
        }
        return extension;
    }
}

4、工具类

/**
     * 日期路径 即年/月/日 如2018/08/08
     */
    public static final String datePath()
    {
        Date now = new Date();
        return DateFormatUtils.format(now, "yyyy/MM/dd");
    }

package com.xinruan.common.core.utils.file;

/**
 * 媒体类型工具类
 * 
 * @author ruoyi
 */
public class MimeTypeUtils
{
    public static final String IMAGE_PNG = "image/png";

    public static final String IMAGE_JPG = "image/jpg";

    public static final String IMAGE_JPEG = "image/jpeg";

    public static final String IMAGE_BMP = "image/bmp";

    public static final String IMAGE_GIF = "image/gif";

    public static final String[] IMAGE_EXTENSION = { "bmp", "gif", "jpg", "jpeg", "png" };

    public static final String[] FLASH_EXTENSION = { "swf", "flv" };

    public static final String[] MEDIA_EXTENSION = { "swf", "flv", "mp3", "wav", "wma", "wmv", "mid", "avi", "mpg",
            "asf", "rm", "rmvb" };

    public static final String[] VIDEO_EXTENSION = { "mp4", "avi", "rmvb" };

    public static final String[] DEFAULT_ALLOWED_EXTENSION = {
            // 图片
//            "bmp", "gif", "jpg", "jpeg", "png",
//            // word excel powerpoint
//            "doc", "docx", "xls", "xlsx", "ppt", "pptx", "html", "htm", "txt",
//            // 压缩文件
//            "rar", "zip", "gz", "bz2",
//            // 视频格式
//            "mp4", "avi", "rmvb",
//            // pdf
//            "pdf"
            "pdf", "bmp", "jpg", "JPEG", "png", "zip", "rar"
    };

    public static String getExtension(String prefix)
    {
        switch (prefix)
        {
            case IMAGE_PNG:
                return "png";
            case IMAGE_JPG:
                return "jpg";
            case IMAGE_JPEG:
                return "jpeg";
            case IMAGE_BMP:
                return "bmp";
            case IMAGE_GIF:
                return "gif";
            default:
                return "";
        }
    }
}

package com.xinruan.common.core.utils.uuid;

import java.util.concurrent.atomic.AtomicInteger;
import com.xinruan.common.core.utils.DateUtils;
import com.xinruan.common.core.utils.StringUtils;

/**
 * @author ruoyi 序列生成类
 */
public class Seq
{
    // 通用序列类型
    public static final String commSeqType = "COMMON";

    // 上传序列类型
    public static final String uploadSeqType = "UPLOAD";

    // 通用接口序列数
    private static AtomicInteger commSeq = new AtomicInteger(1);

    // 上传接口序列数
    private static AtomicInteger uploadSeq = new AtomicInteger(1);

    // 机器标识
    private static String machineCode = "A";

    /**
     * 获取通用序列号
     * 
     * @return 序列值
     */
    public static String getId()
    {
        return getId(commSeqType);
    }
    
    /**
     * 默认16位序列号 yyMMddHHmmss + 一位机器标识 + 3长度循环递增字符串
     * 
     * @return 序列值
     */
    public static String getId(String type)
    {
        AtomicInteger atomicInt = commSeq;
        if (uploadSeqType.equals(type))
        {
            atomicInt = uploadSeq;
        }
        return getId(atomicInt, 3);
    }

    /**
     * 通用接口序列号 yyMMddHHmmss + 一位机器标识 + length长度循环递增字符串
     * 
     * @param atomicInt 序列数
     * @param length 数值长度
     * @return 序列值
     */
    public static String getId(AtomicInteger atomicInt, int length)
    {
        String result = DateUtils.dateTimeNow();
        result += machineCode;
        result += getSeq(atomicInt, length);
        return result;
    }

    /**
     * 序列循环递增字符串[1, 10 的 (length)幂次方), 用0左补齐length位数
     * 
     * @return 序列值
     */
    private synchronized static String getSeq(AtomicInteger atomicInt, int length)
    {
        // 先取值再+1
        int value = atomicInt.getAndIncrement();

        // 如果更新后值>=10 的 (length)幂次方则重置为1
        int maxSeq = (int) Math.pow(10, length);
        if (atomicInt.get() >= maxSeq)
        {
            atomicInt.set(1);
        }
        // 转字符串，用0左补齐
        return StringUtils.padl(value, length);
    }
}

转自若依官方代码