获取二进制流时收到以下异常。
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)
我正在使用：Hibernate 4.1.1，MS SQL Server 2008和最新的MS SQL JDBC4驱动程序。 我使用以下自定义映射类型“BlobToStreamUserType”从SQL Blob（varchar（max））映射到InputStream。 Hibernate似乎没有提供将SQL BLOB映射到Java InputStream的类型，MaterializedBlobType只将SQL BLOB映射到Java byte []。
我使用'rs.getBinaryStream'来返回真正的二进制流而不是内存中缓冲的流，原因是我们有大图像，如果同时访问多个用户会导致内存问题。
根据微软的说法
Microsoft驱动程序遵循关于getBinaryStream =＆gt;的JDBC规范。 注意：必须在获取任何＆gt;其他列的值之前读取返回流中的所有数据。下一次调用getter方法会隐式关闭流。此外，当调用方法InputStream.available时，流＆gt;可以返回0，无论是否存在数据＆gt;
因此getBinaryStream旨在返回真正的字节流。我们返回一个未在内存中缓冲的真正流＆gt;字节，它是从服务器响应中直接读取的流＆gt;。在获取我们实现的所有＆gt;字节之前，您无法关闭contentDataResultSet。
我已经尝试将hibernate属性'hibernate.jdbc.use_streams_for_binary'设置为true和false但是这没有区别。
这是我的代码：
图像实体类，显示到自定义用户类型的映射。
import java.io.InputStream;
import java.util.Date;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
import org.hibernate.annotations.DynamicInsert;
import org.hibernate.annotations.DynamicUpdate;
import org.hibernate.annotations.GenericGenerator;
import org.hibernate.annotations.Type;
import com.google.common.base.Objects;
@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;
}
}
这是我的自定义映射类型：
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.");
}
}
这是我的DAO来检索图像流
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以下解决方法绕过hibernate并直接从结果集中检索流，并允许我毫无例外地读取流。但是我宁愿使用hibernate映射来检索真正的二进制流。
修改DAO方法
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;
}
答案 0 :(得分：0)
您是否尝试将该类型标记为Lob？
@Lob
@Column(name = "image")
@Type(type = "my.package.BlobToStreamUserType")
Blob blob;
public Blob getBlob(){
return blob;
}
当你需要使用流？
final InputStream is;
try {
is = blob.getBinaryStream();
//do some work
}
知道你可以简单地找回一个Blob会很有帮助 在定义自己的类型之前。
答案 1 :(得分：0)