Base64与MultipartFile互转

Base64转MultipartFile

import org.springframework.web.multipart.MultipartFile;
import sun.misc.BASE64Decoder;

public static MultipartFile base64ToMultipartFile (String s) {
        MultipartFile image = null;
        StringBuilder base64 = new StringBuilder("");
        if (s != null && !"".equals(s)) {
            base64.append(s);
            String[] baseStrs = base64.toString().split(",");
            BASE64Decoder decoder = new BASE64Decoder();
            byte[] b = new byte[0];
            try {
                b = decoder.decodeBuffer(baseStrs[1]);
            } catch (IOException e) {
                e.printStackTrace();
            }
            for (int j = 0; j < b.length; ++j) {
                if (b[j] < 0) {
                    b[j] += 256;
                }
            }
            image = new  BASE64DecodedMultipartFile(b, baseStrs[0]);
        }
        return image;
    }

package com.hssmartcity.common.utils;

import org.springframework.web.multipart.MultipartFile;

import java.io.*;

/**
 * @ClassName BASE64DecodedMultipartFile
 * @Description TODO
 * @Author syh
 * @Date 2023/8/7 10:48
 */
public class BASE64DecodedMultipartFile implements MultipartFile {

    private final byte[] imgContent;
    private final String header;

    public BASE64DecodedMultipartFile(byte[] imgContent, String header) {
        this.imgContent = imgContent;
        this.header = header.split(";")[0];
    }

    @Override
    public String getName() {
        return System.currentTimeMillis() + Math.random() + "." + header.split("/")[1];
    }

    @Override
    public String getOriginalFilename() {
        return System.currentTimeMillis() + (int) Math.random() * 10000 + "." + header.split("/")[1];
    }

    @Override
    public String getContentType() {
        return header.split(":")[1];
    }

    @Override
    public boolean isEmpty() {
        return imgContent == null || imgContent.length == 0;
    }

    @Override
    public long getSize() {
        return imgContent.length;
    }

    @Override
    public byte[] getBytes() throws IOException {
        return imgContent;
    }

    @Override
    public InputStream getInputStream() throws IOException {
        return new ByteArrayInputStream(imgContent);
    }

    @Override
    public void transferTo(File dest) throws IOException, IllegalStateException {
        new FileOutputStream(dest).write(imgContent);
    }

}

MultipartFile转Base64

import org.springframework.web.multipart.MultipartFile;
import sun.misc.BASE64Encoder;

import java.io.IOException;

/**
 * @ClassName FilesUtils
 * @Description 文件工具类
 * @Author syh
 * @Date 2023/9/13 14:40
 */
public class FilesUtils {

    /**
     * 将MultipartFile 图片文件编码为base64
     *
     * @param file
     * @return
     * @throws Exception
     */
    public static String generateBase64(MultipartFile file) {
        if (file == null || file.isEmpty()) {
            throw new RuntimeException("图片不能为空！");
        }
        String fileName = file.getOriginalFilename();
        String fileType = fileName.substring(fileName.lastIndexOf("."));
        String contentType = file.getContentType();
        byte[] imageBytes = null;
        String base64EncoderImg = "";
        try {
            imageBytes = file.getBytes();
            BASE64Encoder base64Encoder = new BASE64Encoder();
            /**
             * 1.Java使用BASE64Encoder 需要添加图片头（"data:" + contentType + ";base64,"），
             *   其中contentType是文件的内容格式。
             * 2.Java中在使用BASE64Enconder().encode()会出现字符串换行问题，这是因为RFC 822中规定，
             *   每72个字符中加一个换行符号，这样会造成在使用base64字符串时出现问题，
             *   所以我们在使用时要先用replaceAll("[\\s*\t\n\r]", "")解决换行的问题。
             */
            base64EncoderImg = "data:" + contentType + ";base64," + base64Encoder.encode(imageBytes);
            base64EncoderImg = base64EncoderImg.replaceAll("[\\s*\t\n\r]", "");
        } catch (IOException e) {
            e.printStackTrace();
        }
        return base64EncoderImg;
    }

}