kotlin File转换MultipartFile

import org.apache.commons.fileupload.disk.DiskFileItemFactory
import org.springframework.web.multipart.MultipartFile
import org.springframework.web.multipart.commons.CommonsMultipartFile
import java.io.File
import java.io.FileInputStream



/**
     * file转multipartFile
     */
    fun  fileToMultipartFile(file: File ) : MultipartFile {
        val factory = DiskFileItemFactory(16, null);
        val item=factory.createItem(file.name,"text/plain",true,file.name);
        var bytesRead = 0;
        val buffer = ByteArray(8192)

        try {
            val fis =  FileInputStream(file);
            val os = item.outputStream;
            while ((fis.read(buffer, 0, 8192).also { bytesRead = it }) != -1) {
                os.write(buffer, 0, bytesRead);
            }
            os.close();
            fis.close();
        }  catch (e: Exception) {
            e.printStackTrace()
        }
        return  CommonsMultipartFile(item);
    }