java上传实现 spring boot +element ui

先从element ui el-upload组件开始介绍。

<el-upload
    name="file"
    :show-file-list="false"
    action="请求controller的地址"
    :on-success="handleUploadSuccessletter" 上传成功做的一些操作
    :headers="headers"  获得的headers一个身份的验证
>
  <el-link type="primary">重新上传</el-link>    //这里需要一个点击控件即可，el-button也行
</el-upload>

关于headers

在return里写，这个即可获得headers

headers: {
  Authorization: "Bearer " + getToken(),
},

目录

1、得到文件上传路径，getUploadPath方法

2、FileUploadUtils里的upload方法，返回一个新的文件名

3、获取url 

完整的FileUploadUtils 

再来看后台controller

@PostMapping("/upload")
public ResultJson uploadFile(MultipartFile file) throws Exception {
    try {
        // 上传文件路径，其中Config是一个Java类，里面有文件上传到路径
        String filePath = Config.getUploadPath();
        // 上传并返回新文件名称
        String fileName = FileUploadUtils.upload(filePath, file);
        String url = serverConfig.getUrl() + fileName;
        Map<String, String> prams = new HashMap<String, String>();//定义一个map
        prams.put("fileName", fileName);
        prams.put("url", url);//分别放入文件名和url
        return ResultJson.ok(prams); //返回给前台
    } catch (Exception e) {
        return ResultJson.failure(ResultCode.BAD_REQUEST, e.getMessage());
    }
}

大致步骤分为以下：

1、得到文件上传路径，getUploadPath方法

/**
     * 获取上传路径
     */
    public static String getUploadPath()
    {
        return getProfile() + "upload";
    }

我们再来看getProfile()方法：

public static String getProfile()
    {
        return profile;
    }

这里的profile是自己定义的一个路径

2、FileUploadUtils里的upload方法，返回一个新的文件名

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);
    }
}

上面的upload方法，又调用了一个upload方法，如下：（这个upload方法一个是校验文件名的长度，以及校验文件是否符合大小，并返回一个新的文件名）

public static final String upload(String baseDir, MultipartFile file, String[] allowedExtension)  //接收文件上传路径，文件名，文件类型
        throws FileSizeLimitExceededException, IOException, FileNameLengthLimitExceededException,
        InvalidExtensionException
{
//检验文件名字的长度是否超过规定
    int fileNamelength = file.getOriginalFilename().length();
    if (fileNamelength > FileUploadUtils.DEFAULT_FILE_NAME_LENGTH)
    {
        throw new FileNameLengthLimitExceededException(FileUploadUtils.DEFAULT_FILE_NAME_LENGTH);
    }
//文件的大小是否合格
    assertAllowed(file, allowedExtension);
//获取编码文件名
    String fileName = extractFilename(file);

    File desc = getAbsoluteFile(baseDir, fileName);
    file.transferTo(desc);
    String pathFileName = getPathFileName(baseDir, fileName);
    return pathFileName;
}

//检验文件名字的长度是否超过规定//文件的大小是否合格

/**
 * 文件大小校验
 *
 * @param file 上传的文件
 * @return
 * @throws FileSizeLimitExceededException 如果超出最大大小
 * @throws InvalidExtensionException
 */
public static final void assertAllowed(MultipartFile file, String[] allowedExtension)
        throws FileSizeLimitExceededException, InvalidExtensionException
{
    long size = file.getSize();
    if (DEFAULT_MAX_SIZE != -1 && size > DEFAULT_MAX_SIZE)
    {
        throw new FileSizeLimitExceededException(DEFAULT_MAX_SIZE / 1024 / 1024);
    }

    String fileName = file.getOriginalFilename();
    String extension = getExtension(file);
    if (allowedExtension != null && !isAllowedExtension(extension, allowedExtension))
    {
        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
        {
            throw new InvalidExtensionException(allowedExtension, extension, fileName);
        }
    }

}

//获取编码文件名 

/**
 * 编码文件名
 */
public static final String extractFilename(MultipartFile file)
{
    String fileName = file.getOriginalFilename();
    String extension = getExtension(file);
    fileName = DateUtils.datePath() + "/" + IdUtils.fastUUID() + "." + extension;
    return fileName;
}

得到绝对文件

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

    if (!desc.getParentFile().exists())
    {
        desc.getParentFile().mkdirs();
    }
    if (!desc.exists())
    {
        desc.createNewFile();
    }
    return desc;
}

最终返回新的文件名 

private static final String getPathFileName(String uploadDir, String fileName) throws IOException
{
    int dirLastIndex = NiuaConfig.getProfile().length();
    String currentDir = StringUtils.substring(uploadDir, dirLastIndex);
    String pathFileName = Constants.RESOURCE_PREFIX + "/" + currentDir + "/" + fileName;
    return pathFileName;
}

MimeTypeUtils.DEFAULT_ALLOWED_EXTENSION这个是允许上传的文件类型

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",
        // pdf
        "pdf" ,"mp4"};

3、获取url 

/**
     * 获取完整的请求路径，包括：域名，端口，上下文访问路径
     *
     * @return 服务地址
     */
    public String getUrl()
    {
        HttpServletRequest request = ServletUtils.getRequest();
        return getDomain(request);
    }

4、分别将url和文件名传给前台

前台接收：

handleUploadSuccess(res) {
  let uploadUrlPath = res;
  this.dialogForm.imageUrl = uploadUrlPath.data.url
  this.loading.close();
},

完整的FileUploadUtils 

package tech.niua.common.utils.file;

import java.io.File;
import java.io.IOException;
import org.apache.commons.io.FilenameUtils;
import org.springframework.web.multipart.MultipartFile;
import tech.niua.common.config.NiuaConfig;
import tech.niua.common.constant.Constants;
import tech.niua.common.exception.file.FileNameLengthLimitExceededException;
import tech.niua.common.exception.file.FileSizeLimitExceededException;
import tech.niua.common.exception.file.InvalidExtensionException;
import tech.niua.common.utils.DateUtils;
import tech.niua.common.utils.StringUtils;
import tech.niua.common.utils.uuid.IdUtils;

/**
 * @author 
 * @title: FileUploadUtils
 * @projectName niua_easy_parent
 * @description: 文件上传工具
 * @date 2020/12/19 下午9:49
 */
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;

    /**
     * 默认上传的地址
     */
    private static String defaultBaseDir = NiuaConfig.getProfile();

    public static void setDefaultBaseDir(String defaultBaseDir)
    {
        FileUploadUtils.defaultBaseDir = defaultBaseDir;
    }

    public static String getDefaultBaseDir()
    {
        return defaultBaseDir;
    }

    /**
     * 以默认配置进行文件上传
     *
     * @param file 上传的文件
     * @return 文件名称
     * @throws Exception
     */
    public static final String upload(MultipartFile file) throws IOException
    {
        try
        {
            return upload(getDefaultBaseDir(), file, MimeTypeUtils.DEFAULT_ALLOWED_EXTENSION);
        }
        catch (Exception e)
        {
            throw new IOException(e.getMessage(), e);
        }
    }

    /**
     * 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);  //校验文件格式
        }
        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 = file.getOriginalFilename().length();
        if (fileNamelength > FileUploadUtils.DEFAULT_FILE_NAME_LENGTH)
        {
            throw new FileNameLengthLimitExceededException(FileUploadUtils.DEFAULT_FILE_NAME_LENGTH);
        }

        assertAllowed(file, allowedExtension);

        String fileName = extractFilename(file);

        File desc = getAbsoluteFile(baseDir, fileName);
        file.transferTo(desc);
        String pathFileName = getPathFileName(baseDir, fileName);
        return pathFileName;
    }

    /**
     * 编码文件名
     */
    public static final String extractFilename(MultipartFile file)
    {
        String fileName = file.getOriginalFilename();
        String extension = getExtension(file);
        fileName = DateUtils.datePath() + "/" + IdUtils.fastUUID() + "." + extension;
        return fileName;
    }

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

        if (!desc.getParentFile().exists())
        {
            desc.getParentFile().mkdirs();
        }
        if (!desc.exists())
        {
            desc.createNewFile();
        }
        return desc;
    }

    private static final String getPathFileName(String uploadDir, String fileName) throws IOException
    {
        int dirLastIndex = NiuaConfig.getProfile().length();
        String currentDir = StringUtils.substring(uploadDir, dirLastIndex);
        String pathFileName = Constants.RESOURCE_PREFIX + "/" + currentDir + "/" + fileName;
        return pathFileName;
    }

    /**
     * 文件大小校验
     *
     * @param file 上传的文件
     * @return
     * @throws FileSizeLimitExceededException 如果超出最大大小
     * @throws InvalidExtensionException
     */
    public static final void assertAllowed(MultipartFile file, String[] allowedExtension)
            throws FileSizeLimitExceededException, InvalidExtensionException
    {
        long size = file.getSize();
        if (DEFAULT_MAX_SIZE != -1 && size > DEFAULT_MAX_SIZE)
        {
            throw new FileSizeLimitExceededException(DEFAULT_MAX_SIZE / 1024 / 1024);
        }

        String fileName = file.getOriginalFilename();
        String extension = getExtension(file);
        if (allowedExtension != null && !isAllowedExtension(extension, allowedExtension))
        {
            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
            {
                throw new InvalidExtensionException(allowedExtension, extension, fileName);
            }
        }

    }

    /**
     * 判断MIME类型是否是允许的MIME类型
     *
     * @param extension
     * @param allowedExtension
     * @return
     */
    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(file.getContentType());
        }
        return extension;
    }
}