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();
