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How to read/write Blob images using Hibernate

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queenHibernate

Post subject: How to read/write Blob images using Hibernate

Posted: Tue Oct 28, 2008 3:49 am

Beginner

Joined: Mon Aug 13, 2007 2:37 am
Posts: 22

Hi guys,

I have a web application where I'm trying to store and retrieve user JPEG images in a MySQL database. I'm using Spring and Hibernate3, but I don't know how to handle blob or binary datatypes.

I would I appreciate it if someone that show my how to configure my hibernate.cfg.xml and how to convert the byte data I get from HTML to the blog datatype I'll be storing in the db using hibernate.

Here's what I have so far:

Code:

<hibernate-mapping>    

<class name="com.RXCoreApp.datamodel.UserImagesCbo" table="User_Images" catalog="RX"> 
       
<id name="userImageId" type="java.lang.Integer">            
<column name="User_Image_Id" />            
<generator class="identity"></generator>        
</id>        

<many-to-one name="users" class="com.RXCoreApp.datamodel.UserCbo" fetch="select">            <column name="User_Id" not-null="true" />        
</many-to-one>        

<property name="userImagePath" type="java.lang.String">            <column name="User_Image_Path" not-null="true" />        </property>        

<property name="userDefaultFlag" type="java.lang.String">            <column name="User_Default_flag" length="1" />        
</property>        

<property name="imageContent" type="java.sql.blob">            
<column name="Image_Content" sql-type="BLOB" />        </property>     

</class>
</hibernate-mapping>

I'm clueless dealing with blobs...Please help!

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Rober2D2

Post subject:

Posted: Tue Oct 28, 2008 7:19 pm

Beginner

Joined: Tue Oct 30, 2007 7:57 am
Posts: 47

The mapping seems correct (just change java.sql.blob for java.sql.Blob, or just by blob).

To create the blob when you wish to write, just use the helpers that come with the class org.hibernate.Hibernate. There are several static methods called createBlob

You may create blobs form InputStream, byte[] ....

To read data from a blob, just use the method getBinaryStream().

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queenHibernate

Post subject:

Posted: Thu Nov 06, 2008 4:53 pm

Beginner

Joined: Mon Aug 13, 2007 2:37 am
Posts: 22

I tried your suggestion, BUT the actual BLOB content is not being SAVED in the database. however, the other fields in my USER_IMAGE table are being writed to the database.

Here's what I'm doing:

1. Populate entity bean

Code:

   FormFile imageFile = (FormFile) images[x];    
                       userImageCbo.setUsers(userCbo);
                                 userImageCbo.setUserDefaultFlag(defaultFlag);
                                 userImageCbo.setUserImagePath(destinationPath);
                                 userImageCbo.setImageDataContents( Hibernate.createBlob(imageFile.getFileData() )    );

2. Invoke my Hibernate DAO

Code:

userImagesDao.save(userImageCbo);

3. Spring-Hibernate DAO

Code:

    public void save(UserImagesCbo userImagesCbo) {


        try {
           this.getHibernateTemplate().save(userImagesCbo);

        } catch (RuntimeException re) {
            log.error("save failed", re);
            throw re;
        }
    }

The database is not throwing an error, but this is the contents of my blob field in MySQL:

Code:

[BLOB - NULL]

what I'm I doing wrong??? Please help

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