I receive the following exception when getting a binary stream.
Code:
java.io.IOException: The stream is closed.
at com.microsoft.sqlserver.jdbc.BaseInputStream.checkClosed(SimpleInputStream.java:93)
at com.microsoft.sqlserver.jdbc.PLPInputStream.read(PLPInputStream.java:237)
at au.gov.vic.doi.tp.service.binary.dao.BinaryDAOImplTest.retrieveBinary(BinaryDAOImplTest.java:102)
I am using: Hibernate 4.1.1, MS SQL Server 2008 and the latest MS SQL JDBC4 driver.
I use the following custom mapping type 'BlobToStreamUserType' to map from SQL Blob (varchar(max)) to InputStream. Hibernate don't appear to provide a type that maps an SQL BLOB to Java InputStream, the MaterializedBlobType only maps an SQL BLOB to Java byte[].
I am using 'rs.getBinaryStream' to return a true binary stream not a stream buffered in memory, the reason being is that we have large images that if multiple users accessed concurrently would cause memory issues.
According to microsoft
Quote:
The Microsoft driver follows the JDBC spec with respect to getBinaryStream =>
Note: All the data in the returned stream must be read prior to getting the value of any other column. The next call to a getter method implicitly closes the stream. Also, a stream may return 0 when the method InputStream.available is called whether there is data available or not.
So getBinaryStream is designed to return a true stream of bytes. We return a true stream of bytes that is NOT buffered in memory, it is a stream that is read right off the wire from the server response. You cannot close the contentDataResultSet until you fetch all the bytes for our implementation.
I have tried setting the hibernate property 'hibernate.jdbc.use_streams_for_binary' to true and false however this makes no difference.
Here is my code:
Image entity class showing mapping to custom user type.
Code:
@Entity
@DynamicInsert(false)
@DynamicUpdate(false)
@Table(name = "Binary")
public class Binary
{
.........
@Lob
@Column(name = "image")
@Type(type = "my.package.BlobToStreamUserType")
public InputStream getImageStream()
{
return this.imageStream;
}
}
here is my custom mapping type:
Code:
public class BlobToStreamUserType implements UserType
{
public int[] sqlTypes()
{
return new int[]
{ Types.BLOB };
}
public Class returnedClass()
{
return InputStream.class;
}
public Object nullSafeGet(final ResultSet rs, final String[] names, final SessionImplementor session,
final Object owner) throws HibernateException, SQLException
{
return rs.getBinaryStream(names[0]);
}
public void nullSafeSet(final PreparedStatement st, final Object value, final int index,
final SessionImplementor session) throws HibernateException, SQLException
{
if (value != null)
{
if (!InputStream.class.isAssignableFrom(value.getClass()))
{
throw new HibernateException(value.getClass().toString() + " cannot be cast to a java.IO.InputStream");
}
InputStream inStream = (InputStream) value;
st.setBinaryStream(index, inStream);
}
else
{
st.setBytes(index, null);
}
}
public boolean equals(final Object x, final Object y) throws HibernateException
{
return ObjectUtils.equals(x, y);
}
public int hashCode(final Object x) throws HibernateException
{
assert (x != null);
return x.hashCode();
}
public Object deepCopy(final Object value) throws HibernateException
{
return value;
}
public boolean isMutable()
{
return false;
}
public Object replace(final Object original, final Object target, final Object owner) throws HibernateException
{
return original;
}
public Serializable disassemble(final Object value) throws HibernateException
{
//disassemble() is only called when caching the data in the second-level cache
// also safe for mutable objects
throw new UnsupportedOperationException("Not supported yet.");
}
public Object assemble(final Serializable cached, final Object owner) throws HibernateException
{
throw new UnsupportedOperationException("Not supported yet.");
}
}
and here is my DAO to retrieve the image stream
Code:
public class BinaryDAOImpl extends AbstractSpringHibernateDAO implements BinaryDAO
{
public Binary getBinary(final String amsAssetId, final String assetMaintainer, final String variant,
final Integer sequence) throws GetException
{
try
{
Query query = super.getSession().createQuery(
"from Binary bin where bin.amsAssetId = :amsAssetId and bin.assetMaintainer = :assetMaintainer "
+ "and bin.variant = :variant and bin.sequence = :sequence");
query.setParameter("amsAssetId", amsAssetId);
query.setParameter("assetMaintainer", assetMaintainer);
query.setParameter("variant", variant);
query.setParameter("sequence", sequence);
return query.uniqueResult();
}
N.b The following workaround to bypass hibernate and retrieve the stream directly from the result set works and allows me to read the stream without exception. However I would rather use hibernate to map from a blob to stream if possible.
Modified DAO method
Code:
public Binary getBinary(final String amsAssetId, final String assetMaintainer, final String variant,
final Integer sequence) throws GetException
{
try
{
Query query = super.getSession().createQuery(
"from Binary bin where bin.amsAssetId = :amsAssetId and bin.assetMaintainer = :assetMaintainer "
+ "and bin.variant = :variant and bin.sequence = :sequence");
query.setParameter("amsAssetId", amsAssetId);
query.setParameter("assetMaintainer", assetMaintainer);
query.setParameter("variant", variant);
query.setParameter("sequence", sequence);
Binary binary = (Binary) query.uniqueResult();
final String id = binary.getId();
// Necessary until Hibernate supports InputStream mapping
binary.setImageStream(getSession().doReturningWork(new ReturningWork<InputStream>()
{
public InputStream execute(final Connection connection) throws SQLException
{
PreparedStatement statement = connection.prepareStatement("select image from Binary where id=?",
ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_READ_ONLY);
statement.setString(1, id);
ResultSet resultSet = statement.executeQuery();
return (resultSet.first() ? resultSet.getBinaryStream(1) : null);
}
}));
return binary;
}
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