使用Hibernaet存储MYSQL表中BLOB字段的有关问题
使用Hibernaet存储MYSQL表中BLOB字段的问题
org.hibernate.exception.SQLGrammarException: could not insert: [cn.com.servyou.bbs.domain.Image]
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:90)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:64)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2186)
at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2666)
at org.hibernate.action.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:71)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:279)
at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:321)
at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:204)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:130)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:210)
at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:56)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:195)
at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:50)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)
at org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:562)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:550)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:546)
。。。
Caused by: com.mysql.jdbc.exceptions.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '$T??ú2{??÷?#M`9;? ¤?2?tJp>1?÷D?<???Pm?òQ?mn?????Nè\'?.89??4…
.?\'U\0??0?' at line 1
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1051)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3562)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3494)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1960)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2114)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2696)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2105)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2398)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2316)
at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2301)
at org.hibernate.id.IdentityGenerator$GetGeneratedKeysDelegate.executeAndExtract(IdentityGenerator.java:94)
at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:57)
... 17 more
在网上查阅了很多资料，自己也经过测试，使用纯JDBC代码进行测试，发现了这样一个问题。
用纯JDBC代码是可以将图片的二进制流存入数据库表的相应字段的。如果是用Hibernate存储CLOB字段是没有问题的，但是在存储BLOB字段时会出现问题。
错误可能的原因：
1. 使用了MYSQL 的保留字作为表字段名
2. 字符集的问题，需要在Hibernate配置文件中，对数据库连接URL指定编码
jdbc:mysql://127.0.0.1:3306/hibernate_demo?useUnicode=true&characterEncoding=utf-8
先给出数据库脚本及配置。。。
数据库表创建脚本：
create table t_test( id int(11) not null auto_increment, photo mediumblob, primary key(id) )
Hibernate配置文件：
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- 显示实际操作资料库时的SQL -->
<property name="show_sql">true</property>
<!-- 格式化SQL -->
<property name="format_sql">true</property>
<!-- SQL方言，这边设定的是MySQL -->
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<!-- JDBC驱动程式 -->
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<!-- JDBC URL -->
<property name="connection.url">jdbc:mysql://127.0.0.1:3306/hibernate_demo</property>
<!-- 数据库使用者 -->
<property name="connection.username">root</property>
<!-- 数据库密码 -->
<property name="connection.password">123456</property>
<property name="hbm2ddl.auto">none</property>
<!-- 加入二级缓存 -->
<!--
<property name="hibernate.cache.use_query_cache">true</property>
<property name="hibernate.cache.use_second_level_cache">true</property>
<property name="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider</property>
-->
<!-- C3P0连接池配置 -->
<property name="c3p0.min_size">5</property>
<property name="c3p0.max_size">20</property>
<property name="c3p0.timeout">1800</property>
<property name="c3p0.max_statements">50</property>
<!-- 以下设置物件与资料库表格映射文件 -->
<mapping resource="cn/com/servyou/bbs/domain/Image.hbm.xml" />
</session-factory>
</hibernate-configuration>
Image映射配置文件：
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="cn.com.servyou.bbs.domain.Image" table="t_test">
<id name="id" column="id" type="java.lang.Integer">
<generator class="native" />
</id>
<property name="blob" column="photo" type="java.sql.Blob"></property>
</class>
</hibernate-mapping>
为了便于大家理解这里给出HibernateSessionFactory和FileUtil的代码，HibernateSessionFactory主要是将session与当前使用的线程进行绑定：
HibernateSessionFactory:
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
public class HibernateSessionFactory {
private static ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
private static String CONFIG_FILE_LOCATION = "hibernate-cfg.xml";
private static SessionFactory sessionFactory;
static {
Configuration conf = new Configuration()
.configure(CONFIG_FILE_LOCATION);
sessionFactory = conf.buildSessionFactory();
}
public static Session getSession() {
Session session = threadLocal.get();
if (null == session) {
if (null == sessionFactory) {
Configuration conf = new Configuration()
.configure(CONFIG_FILE_LOCATION);
sessionFactory = conf.buildSessionFactory();
}
session = sessionFactory.openSession();
threadLocal.set(session);
}
return session;
}
public static void closeSession() {
Session session = threadLocal.get();
threadLocal.set(null);
if (null != session && session.isOpen()) {
session.close();
}
}
}
FileUtil(想必也没什么好解释的了哈):
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
public class FileUtil {
public static byte[] getBytes(String path) {
BufferedInputStream bis = null;
ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
try {
bis = new BufferedInputStream(new FileInputStream(path));
byte[] bytes = new byte[8096];
int index;
while ((index = bis.read(bytes)) != -1) {
byteArrayOutputStream.write(bytes, 0, index);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (null != bis) {
try {
bis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if (null != byteArrayOutputStream) {
try {
byteArrayOutputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return byteArrayOutputStream.toByteArray();
}
public static void writeFile(InputStream inputStream, String destFilePath) {
BufferedOutputStream bos = null;
BufferedInputStream bis = null;
try {
bos = new BufferedOutputStream(new FileOutputStream(destFilePath));
bis = new BufferedInputStream(inputStream);
byte[] buffer = new byte[8096];
int index = -1;
while ((index = bis.read(buffer)) != -1) {
bos.write(buffer, 0, index);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (null != bos)
try {
bos.close();
} catch (IOException e) {
e.printStackTrace();
}
if (null != bis)
try {
bis.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
使用JDBC代码测试，观察能否将图片二进制流存入数据库（我本机的“D:\\My Documents\\My Pictures\\”目录下放了一个20090731124506989.jpg图片，可以自行指定）：
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.sql.Blob;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import cn.com.servyou.bbs.util.FileUtil;
public class WriteAndReadImage {
public static Connection getConnection() {
Connection conn = null;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection(
"jdbc:mysql://localhost:3306/hibernate_demo", "root",
"xxxxxx");
} catch (ClassNotFoundException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
return conn;
}
public static void writeImage() throws IOException, SQLException {
Connection conn = getConnection();
PreparedStatement ps = (PreparedStatement) conn
.prepareStatement("insert into t_test(photo) values (?)");
File imgFile = new File(
"D:\\My Documents\\My Pictures\\20090731124506989.jpg");
InputStream inputStream = new FileInputStream(imgFile);
byte[] bytes = FileUtil
.getBytes("D:\\My Documents\\My Pictures\\20090731124506989.jpg");
ps.setBinaryStream(1, inputStream, (int) imgFile.length());
ps.setBytes(1, bytes);
int flag = ps.executeUpdate();
System.out.println(flag);
}
public static void readImage() throws IOException, SQLException {
Connection conn = getConnection();
PreparedStatement ps = conn
.prepareStatement("select photo from t_test");
ResultSet rs = ps.executeQuery();
int count = 1;
while (rs.next()) {
Blob blob = rs.getBlob("photo");
InputStream inputStream = blob.getBinaryStream();
FileUtil.writeFile(inputStream, "D:\\a"+count+++".jpg");
}
}
public static void main(String[] args){
//1.先注释掉readImage() 2.注释掉readImage()
try {
writeImage();
//readImage();
} catch (IOException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
执行后， 测试结果打印“1”，那么就说明插入成功了。哎，总算用JDBC把图片存进去了。能否读出来，别急，把writeImage()注释掉。用readImage()方法，看看在D盘根目录能否生成图片文件。我试过后发现可以哈。。。松了一口气，待会再试试为什么用Hibernate就无法插入。
检查了下，表结构，不可能是使用了MySQL的保留字。
且当使用如下Hibernate测试代码的时候，可以通过：
import java.io.InputStream;
import java.sql.Blob;
import java.sql.SQLException;
import org.hibernate.Hibernate;
import org.hibernate.Session;
import cn.com.servyou.bbs.domain.Image;
import cn.com.servyou.bbs.util.FileUtil;
import cn.com.servyou.bbs.util.HibernateSessionFactory;
public class ImageDaoHibernateImplTest {
public static void writeImage() {
Image image = new Image();
byte[] bytes = FileUtil
.getBytes("D:\\My Documents\\My Pictures\\20090731124506989.jpg");
// Blob blob = Hibernate.createBlob(bytes);
Blob blob = Hibernate.createBlob(new byte[]{34,11,-2,55});
image.setBlob(blob);
Session session = HibernateSessionFactory.getSession();
session.save(image);
HibernateSessionFactory.closeSession();
}
public static void readImage() throws SQLException {
Session session = HibernateSessionFactory.getSession();
Image img = (Image) session.load(Image.class, new Integer(2));
Blob blob = img.getBlob();
InputStream inputStream = blob.getBinaryStream();
FileUtil.writeFile(inputStream, "d:\\b.jpg");
}
public static void main(String[] args) {
try {
writeImage();
// readImage();
} catch (Exception e) {
e.printStackTrace();
}
}
}
然而将换成 Blob blob = Hibernate.createBlob(bytes);
//Blob blob = Hibernate.createBlob(new byte[]{34,11,-2,55});
时报错了！
Caused by: com.mysql.jdbc.exceptions.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '$T??ú2{??÷?#M`9;? ¤?2?tJp>1?÷D?<???Pm?òQ?mn?????Nè\'?.89??4…
这让我突然想起了，可能是MySQL字符集问题，将Hibnate配置文件中MySQL 的URL改成
<property name="connection.url">jdbc:mysql://127.0.0.1:3306/hibernate_demo?useUnicode=true&characterEncoding=utf-8</property>
再执行下writeImage()方法，发现执行成功了，数据库表t_test里也有相应记录。
好，那再试试能不能读出来，并把这个二进制流，生成图片文件，放在D盘根目录。
将主函数中的writeImage注释掉。
//writeImage();
readImage();
执行后发现在D盘根目录便生成了图片文件,但是真正原理还没理解清楚，现在只是给出了处理方法。和大家分享下，望能和大家讨论下，到底是什么原因引起的，为什么JDBC操作BLOB没有字符集问题，而在使用Hibernate的API操作BLOB字段会出现问题。