原生JS上传文件（java）

//fileInfo是文件内容（Base64位的字符串）,fileName是文件名称,url是需要上传到的地址
//base64的格式是这样的
//data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAEgAAABIAQMAAABvIyEEAAAABlBMVEUAAABTU1OoaSf
///AAAAAXRSTlMAQObYZgAAAENJREFUeF7tzbEJACEQRNGBLeAasBCza2lLEGx0CxFGG9hBMDDxRy
///72O9FMnIFapGylsu1fgoBdkXfUHLrQgdfrlJN1BdYBjQQm3UAAAAASUVORK5CYII=
public static String uploadFile(String fileInfo,String fileName,String url) throws IOException{
        BufferedOutputStream bos=null;
        if(!EmptyUtils.isEmpty(fileInfo)){
            BASE64Decoder decoder=new BASE64Decoder();
            String suffix=fileInfo.substring(fileInfo.indexOf("/")+1,fileInfo.indexOf(";"));
            fileInfo=fileInfo.substring(fileInfo.indexOf(",")+1);
            byte[] fileBytes=decoder.decodeBuffer(fileInfo);
            String baseUrl=url;
            File file=new File(baseUrl);
            if(!file.exists() && !file.isDirectory())
            {   System.out.println("目录不存在需要创建:"+baseUrl);

                file.mkdir();
            }
            for(int i=0;i<fileBytes.length;i++) {
                if(fileBytes[i]<0) {//调整异常数据
                    fileBytes[i]+=256;
                }
            }
            String relativeUrl=UUID.randomUUID().toString().replace("-", "")+"_"+fileName.substring(0,fileName.lastIndexOf("."))+"."+suffix;
            bos=new BufferedOutputStream(new FileOutputStream(new File(file,relativeUrl)));
            bos.write(fileBytes);
            bos.flush();//这个一定要有，否则上传的文件会出现错误，打不开等
            bos.close();
            return baseUrl+"/"+relativeUrl;
        }
        return "";

    }