JPA，Mysql Blob返回的数据太长

Question

byte[]我的实体中有一些字段，例如：

@Entity
public class ServicePicture implements Serializable {
    private static final long serialVersionUID = 2877629751219730559L;
    // seam-gen attributes (you should probably edit these)
    @Id
    @GeneratedValue
    private Long id;
    private String description;

    @Lob
    @Basic(fetch = FetchType.LAZY)
    private byte[] picture;

在我的数据库架构上，该字段设置为，BLOB所以应该没问题。无论如何：每当我尝试插入图片或pdf时-都不比1mb，我只会收到此信息

16:52:27,327 WARN  [JDBCExceptionReporter] SQL Error: 0, SQLState: 22001
16:52:27,327 ERROR [JDBCExceptionReporter] Data truncation: Data too long for column 'picture' at row 1
16:52:27,328 ERROR [STDERR] javax.persistence.PersistenceException: org.hibernate.exception.DataException: could not insert: [de.ac.dmg.productfinder.entity.ServicePicture]
16:52:27,328 ERROR [STDERR]     at org.hibernate.ejb.AbstractEntityManagerImpl.throwPersistenceException(AbstractEntityManagerImpl.java:629)
16:52:27,328 ERROR [STDERR]     at org.hibernate.ejb.AbstractEntityManagerImpl.persist(AbstractEntityManagerImpl.java:218)
16:52:27,328 ERROR [STDERR]     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
16:52:27,328 ERROR [STDERR]     at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
16:52:27,328 ERROR [STDERR]     at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
16:52:27,328 ERROR [STDERR]     at java.lang.reflect.Method.invoke(Unknown Source)
16:52:27,328 ERROR [STDERR]     at org.jboss.seam.persistence.EntityManagerInvocationHandler.invoke(EntityManagerInvocationHandler.java:46)
16:52:27,328 ERROR [STDERR]     at $Proxy142.persist(Unknown Source)

我已经检查了我的MySQL cnf，并将max_allowed参数设置为16M-我缺少什么吗？

Answer 1

这完全取决于用于picture列的列类型。根据您的需要，使用：

• TINYBLOB：最大长度为255个字节
• BLOB：最大长度为65,535字节
• MEDIUMBLOB：最大长度16,777,215字节
• LONGBLOB：最大长度为4,294,967,295字节

请注意，如果您是通过JPA批注生成表的，则可以通过指定的length属性来“控制” MySQL将使用的类型Column，例如：

@Lob @Basic(fetch = FetchType.LAZY)
@Column(length=100000)
private byte[] picture;

根据length，您将获得：

       0 < length <=      255  -->  `TINYBLOB`
     255 < length <=    65535  -->  `BLOB`
   65535 < length <= 16777215  -->  `MEDIUMBLOB`
16777215 < length <=    2³¹-1  -->  `LONGBLOB`