This question has already been answered above. Recently i was working on the requirement to convert byte array object to multipartfile object. There are two ways to achieve this.

Approach 1:

Use the default CommonsMultipartFile where you to use the FileDiskItem object to create it.

Example:

FileItem fileItem = new DiskFileItem("fileData", "application/pdf",true, outputFile.getName(), 100000000, new java.io.File(System.getProperty("java.io.tmpdir")));              
MultipartFile multipartFile = new CommonsMultipartFile(fileItem);

Approach 2:

Create your own custom multipart file object and convert the byte array to multipartfile.

public class CustomMultipartFile implements MultipartFile {

private final byte[] fileContent;

private String fileName;

private String contentType;

private File file;

private String destPath = System.getProperty("java.io.tmpdir");

private FileOutputStream fileOutputStream;

public CustomMultipartFile(byte[] fileData, String name) {
    this.fileContent = fileData;
    this.fileName = name;
    file = new File(destPath + fileName);

}

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

public void clearOutStreams() throws IOException {
if (null != fileOutputStream) {
        fileOutputStream.flush();
        fileOutputStream.close();
        file.deleteOnExit();
    }
}

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

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

This how you can use above CustomMultipartFile object.

String fileName = "intermediate.pdf";
CustomMultipartFile customMultipartFile = new CustomMultipartFile(bytea, fileName);
try {
customMultipartFile.transferTo(customMultipartFile.getFile());
        
} catch (IllegalStateException e) {
    log.info("IllegalStateException : " + e);
} catch (IOException e) {
    log.info("IOException : " + e);
}

This will create the required PDF and store that into

java.io.tmpdir with the name intermediate.pdf

Thanks.

    //Start Photo Upload with Adhaar No// 
    if (simpleLoanDto.getPic() != null && simpleLoanDto.getAdharNo() != null) {
        String ServerDirPath = globalVeriables.getAPath() + "\\";
        File ServerDir = new File(ServerDirPath);
        if (!ServerDir.exists()) {
            ServerDir.mkdirs();
        }
        // Giving File operation permission for LINUX//
        IOperation.setFileFolderPermission(ServerDirPath);
        MultipartFile originalPic = simpleLoanDto.getPic();
        byte[] ImageInByte = originalPic.getBytes();
        FileOutputStream fosFor = new FileOutputStream(
                new File(ServerDirPath + "\\" + simpleLoanDto.getAdharNo() + "_"+simpleLoanDto.getApplicantName()+"_.jpg"));
        fosFor.write(ImageInByte);
        fosFor.close();
    }
    //End  Photo Upload with Adhaar No//