java file转MultipartFile

import org.springframework.web.multipart.MultipartFile;

import org.apache.commons.fileupload.FileItemFactory;

import org.apache.commons.fileupload.disk.DiskFileItemFactory;

import org.apache.commons.fileupload.FileItem;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.File;
import java.io.OutputStream;
import java.net.URLEncoder;

public MultipartFile fileToMultipartFile(File file) {
    FileItem fileItem = createFileItem(file);
    MultipartFile multipartFile = new CommonsMultipartFile(fileItem);
    return multipartFile;
}

private FileItem createFileItem(File file) {
    FileItemFactory factory = new DiskFileItemFactory(16, null);
    FileItem item = factory.createItem("textField", "text/plain", true, file.getName());
    int bytesRead = 0;
    byte[] buffer = new byte[8192];
    try {
        FileInputStream fis = new FileInputStream(file);
        OutputStream os = item.getOutputStream();
        while ((bytesRead = fis.read(buffer, 0, 8192)) != -1) {
            os.write(buffer, 0, bytesRead);
        }
        os.close();
        fis.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return item;
}