关于blob与流互转的问题qq21078159的博客-

网上有好多blob与byte[]互相转换的代码，但是很难找到流直接写入到数据库的。显然流写入效率更高，内存占用更少(不需要把所有数据放到内存里面)，以下便是代码(基于Spring Data JPA的版本的 JDBC的话实现类同)

 import org.hibernate.Hibernate; import org.hibernate.Session; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component;  import javax.annotation.PostConstruct; import javax.persistence.EntityManager; import java.io.IOException; import java.io.InputStream; import java.sql.Blob; import java.sql.SQLException;  @Component public class BlobUtil {     private final static Logger logger = LoggerFactory.getLogger(BlobUtil.class);     @Autowired     private EntityManager entityManager;      private Session session;      @PostConstruct     public void init() {         entityManager = entityManager.getEntityManagerFactory().createEntityManager();         session = entityManager.unwrap(Session.class);     }      public InputStream getStream(Blob blob) {         try {             if (blob != null) {                 return blob.getBinaryStream();             }         } catch (SQLException e) {             logger.error("转化出现错误 {}", e);         }         return null;     }      public Blob getBlob(InputStream inputStream) {         if (inputStream != null) {             try {                 return Hibernate.getLobCreator(session).createBlob(inputStream, inputStream.available());             } catch (IOException e) {                 logger.error("转化出现错误 {}", e);             }         }         return null;     } }