实现图片在前后端的传输

首先前端使用vue，element调用js

onUploadChange(file) {
    
    
      const isImage = (file.raw.type === 'image/jpeg' || file.raw.type === 'image/png' || file.raw.type === 'image/gif');
      const isLimit = file.size / 1024 / 512 < 1;
      if (!isImage) {
    
    
        this.$message.error('上传文件只能是图片格式!')
        return false;
      }
      if (!isLimit)
      {
    
    
        this.$message.error('上传文件大小不能超过 500 KB!')
        return false;
      }
      var reader = new FileReader()
      reader.readAsDataURL(file.raw)
      reader.onload = () => {
    
    
        this.BASE64 = reader.result
      };
    }

获得base64码，往后端传，然后将base64码转化为multifilepart。

package com.zjgsu.online_market.common.lang;

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

import java.io.*;

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() {
    
    
        // TODO - implementation depends on your requirements
        return System.currentTimeMillis() + Math.random() + "." + header.split("/")[1];
    }

    @Override
    public String getOriginalFilename() {
    
    
        // TODO - implementation depends on your requirements
        return System.currentTimeMillis() + (int)Math.random() * 10000 + "." + header.split("/")[1];
    }

    @Override
    public String getContentType() {
    
    
        // TODO - implementation depends on your requirements
        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);
    }


    public static MultipartFile base64ToMultipart(String base64) {
    
    
        try {
    
    
            String[] baseStrs = base64.split(",");

            BASE64Decoder decoder = new BASE64Decoder();
            byte[] b = new byte[0];
            b = decoder.decodeBuffer(baseStrs[1]);

            for(int i = 0; i < b.length; ++i) {
    
    
                if (b[i] < 0) {
    
    
                    b[i] += 256;
                }
            }
            return new BASE64DecodedMultipartFile(b, baseStrs[0]);
        } catch (IOException e) {
    
    
            e.printStackTrace();
            return null;
        }
    }

}

MultipartFile file = BASE64DecodedMultipartFile.base64ToMultipart(image);
/
file.transferTo(new File(realpath));