How to upload file using struts and hiberate?

How to upload file using struts and hibernate?

I spent 5-6 hours figuring out how can I upload a file into Blob in a database. So I decided to write a short article.

Add enctype="multipart/form-data" in the form tag (in JSP)

<html:form method="POST" action="/solution.do" enctype="multipart/form-data">

Add 2 fields in ActionForm, one which is populated via struts framework.
Second one which is read by hibernate i.e. uploadedBlob

// This is filled by the code written in Action Class.
    // This has to be done manually and is not done automatically.
    private Blob uploadedBlob;
    public Blob getUploadedBlob() {
        return uploadedBlob;
    }

    public void setUploadedBlob(Blob uploadedba) {
        this.uploadedBlob = uploadedba;
    }
    
    // This is the actual FormFile which gets populated into the ActionForm
    // by struts framework.
    private FormFile uploadedfile;
    public FormFile getUploadedfile() {
        return uploadedfile;
    }

    public void setUploadedfile(FormFile uploadedfile) {
        this.uploadedfile = uploadedfile;
    } 

Add the following in formbean.hbm.xml

<property column="uploadedfile" name="uploadedBlob" type="blob"/>

In Action Class, convert FormFile to Blob and set it in FormBean (while saving)

// Convert FormFile to a byte Array
        byte[] byteArray=formbean.getUploadedfile().getFileData();
        // Convert this byteArray to a blob
        Blob myblob=Hibernate.createBlob(byteArray);
        formbean.setUploadedBlob(myblob);

For saving this formbean to database use

private boolean saveOrUpdate(SolutionFormBean formbean) 
{
        Session session = null;

        //Transaction object
        // Nothing happens without transaction in hibernate.
        Transaction transaction = null;
        try {
            // This step will read hibernate.cfg.xml
            // and prepare hibernate for use
            SessionFactory sessionFactory = new Configuration()
                                             .configure().buildSessionFactory();
            session = sessionFactory.openSession();
            // Using a transaction is mandatory.
            transaction = session.beginTransaction();
            session.saveOrUpdate(formbean);
            // Commit it
            transaction.commit();
            System.out.println("Done");
            return true;
        } catch (Throwable ex) {
            // Make sure you log the exception, as it might be swallowed
            System.err.println("Initial SessionFactory creation failed." + ex);
            throw new ExceptionInInitializerError(ex);
        } finally {
            // Actual row insertion will happen at this step
            if(session!=null)
            {
                session.flush();
                session.close();
            }
            return true;
        }
    }

While reading Blob from database, you would have to do the reverse, i.e.
convert Blob to byteArray and write to ServletOutputStream

Blob dbBlob = dbBean.getUploadedBlob();
        int bloblength=(int)dbBlob.length();
        byte[] tempByte = dbBlob.getBytes(1, bloblength);
        // Now we have converted blob to byte array.
        ServletOutputStream out = response.getOutputStream();
        // For reading more about this header do check out the following link
        // http://javakafunda.blogspot.com/2011/10/forcing-saveas-using-http-header.html
        response.setHeader("Content-Disposition", "attachment; filename="
                                                       +formbean.getFilename());
        out.write(tempByte);
        out.flush();
        out.close();