base64 转 MultipartFile_hutool base64转化成multifile

base64 文件格式是： 文件头+分号+文件体，例如：data:image/png;base64,VBORw0KGgoAAAANSUhEUgAAAFgAAABtCAYAAAAlIqYqAAAACXBIWX

import org.springframework.web.multipart.MultipartFile;
import sun.misc.BASE64Decoder;
 
import java.io.*;
 
/**
 * base64 转 MultipartFile
 */
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);
    }
 
    public static MultipartFile base64ToMultipart(String base64) {
        try {
            String[] baseStr = base64.split(",");
 
            BASE64Decoder decoder = new BASE64Decoder();
            byte[] b = new byte[0];
            b = decoder.decodeBuffer(baseStr[1]);
            for (int i = 0; i < b.length; ++i) {
                if (b[i] < 0) {
                    b[i] += 256;
                }
            }
            return new Base64DecodedMultipartFile(b, baseStr[0]);
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }
}
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