最近做了一个h5人脸采集demo，后端调用百度人脸检测API对图片质量进行把控，图片参数可以是base64类型或者URL形式。前端把图片压缩然后转为base64传回后端，后端进行质量检测合格后把base64转为MultipartFile上传到文件服务器。

Base64转MultipartFile

import org.springframework.web.multipart.MultipartFile;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.Base64;

/**
 * @author Administrator
 */
public class Base64ToMultipartFile implements MultipartFile {
    private final byte[] fileContent;

    private final String extension;
    private final String contentType;


    /**
     * @param base64
     * @param dataUri     格式类似于: data:image/png;base64
     */
    public Base64ToMultipartFile(String base64, String dataUri) {
        this.fileContent = Base64.getDecoder().decode(base64.getBytes(StandardCharsets.UTF_8));
        this.extension = dataUri.split(";")[0].split("/")[1];
        this.contentType = dataUri.split(";")[0].split(":")[1];
    }

    public Base64ToMultipartFile(String base64, String extension, String contentType) {
        this.fileContent = Base64.getDecoder().decode(base64.getBytes(StandardCharsets.UTF_8));
        this.extension = extension;
        this.contentType = contentType;
    }

    @Override
    public String getName() {
        return "param_" + System.currentTimeMillis();
    }

    @Override
    public String getOriginalFilename() {
        return "file_" + System.currentTimeMillis() + "." + extension;
    }

    @Override
    public String getContentType() {
        return contentType;
    }

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

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

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

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

    @Override
    public void transferTo(File file) throws IOException, IllegalStateException {
        try (FileOutputStream fos = new FileOutputStream(file)) {
            fos.write(fileContent);
        }
    }

}

使用

            final String[] base64Array = base64.split(",");

            // 判断图片是否符合要求 略
            checkImageQuality

            // base64转为流
            String dataUir = base64Array[0];
            String data = base64Array[1];
            MultipartFile multipartFile = new Base64ToMultipartFile(data, dataUir);