用JDBC和HIBERNATE写入ORACLE的blog字段
2008-02-29 23:39
239 查看
Oracle的Blob字段比较特殊,他比long字段的性能要好很多,可以用来保存例如图片之类的二进制数据。
写入Blob字段和写入其它类型字段的方式非常不同,因为Blob自身有一个cursor,你必须使用cursor对blob进行操作,因而你在写入Blob之前,必须获得cursor才能进行写入,那么如何获得Blob的cursor呢?
这需要你先插入一个empty的blob,这将创建一个blob的cursor,然后你再把这个empty的blob的cursor用select查询出来,这样通过两步操作,你就获得了blob的cursor,可以真正的写入blob数据了。
看下面的JDBC的demo,把oraclejdbc.jar这个二进制文件写入数据库表javatest的content字段(这是一个blob型字段)
代码
import java.sql.*;
import java.io.*;
import oracle.sql.*;
public class WriteBlob {
public static void main(String[] args) {
try {
DriverManager.registerDriver( new oracle.jdbc.driver.OracleDriver());
Connection conn = DriverManager.getConnection( "jdbc:oracle:thin:@localhost:1521:orcl" , "fankai" , "fankai" );
conn.setAutoCommit( false );
BLOB blob = null ;
PreparedStatement pstmt = conn.prepareStatement( "insert into javatest(name,content) values(?,empty_blob())" );
pstmt.setString( 1 , "fankai" );
pstmt.executeUpdate();
pstmt.close();
pstmt = conn.prepareStatement( "select content from javatest where name= ? for update" );
pstmt.setString( 1 , "fankai" );
ResultSet rset = pstmt.executeQuery();
if (rset.next()) blob = (BLOB) rset.getBlob( 1 );
String fileName = "oraclejdbc.jar" ;
File f = new File(fileName);
FileInputStream fin = new FileInputStream(f);
System.out.println( "file size = " + fin.available());
pstmt = conn.prepareStatement( "update javatest set content=? where name=?" );
OutputStream out = blob.getBinaryOutputStream();
int count = - 1 , total = 0 ;
byte [] data = new byte [( int )fin.available()];
fin.read(data);
out.write(data);
/*
byte[] data = new byte[blob.getBufferSize()]; 另一种实现方法,节省内存
while ((count = fin.read(data)) != -1) {
total += count;
out.write(data, 0, count);
}
*/
fin.close();
out.close();
pstmt.setBlob( 1 ,blob);
pstmt.setString( 2 , "fankai" );
pstmt.executeUpdate();
pstmt.close();
conn.commit();
conn.close();
} catch (SQLException e) {
System.err.println(e.getMessage());
e.printStackTrace();
} catch (IOException e) {
System.err.println(e.getMessage());
}
}
}
仔细看上例,分三步:
1、插入空blob
into javatest(name,content) values(?,empty_blob());
2、获得blob的cursor
select content from javatest where name= ? for update;
注意!!!必须加for update,这将锁定该行,直至该行被修改完毕,保证不产生并发冲突。
3、update javatest set content=? where name=
用cursor往数据库写数据
这里面还有一点要提醒大家:
JDK1.3带的JDBC2.0规范是不完善的,只有读Blob的接口,而没有写Blob的接口,JDK1.4带的JDBC3.0加入了写Blob的接口。你可以使用JDBC3.0的接口,也可以直接使用Oracle的JDBC的API,我在上例中使用了Oracle的JDBC的API。
另外要注意的是:
java.sql.Blob
oracle.sql.BLOB
注意看blob的大小写,是不一样的。写程序的时候不要搞混了。
下面看看用Hibernate怎么写,原理是一样的,也要分三步,但是代码简单很多
这是Cat对象定义
代码
package com.fankai;
import java.sql.Blob;
public class Cat {
private String id;
private String name;
private char sex;
private float weight;
private Blob image;
public Cat() { }
public String getId() { return id; }
public void setId(String id) { this .id = id; }
public String getName() { return name; }
public void setName(String name) { this .name = name; }
public char getSex() { return sex; }
public void setSex( char sex) { this .sex = sex; }
public float getWeight() { return weight; }
public void setWeight( float weight) { this .weight = weight; }
public Blob getImage() { return image; }
public void setImage(Blob image) { this .image = image;}
}
这是Cat.hbm.xml
代码
<? xml version = "1.0" ?>
<!DOCTYPE hibernate-mapping SYSTEM "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" >
< hibernate-mapping >
< class name = "com.fankai.Cat" table = "cat" >
<!--jcs-cache usage="read-only"/-->
< id name = "id" unsaved-value = "null" >
< generator class = "uuid.hex" />
</ id >
< property name = "name" length = "16" not-null = "true" />
< property name = "sex" length = "1" not-null = "true" />
< property name = "weight" />
< property name = "image" />
</ class >
</ hibernate-mapping >
下面是完整的用Hibernate写入Blob的例子,相比JDBC,已经简单轻松多了,也不用写那些Oracle特殊的sql了:
代码
package com.fankai;
import java.sql.Blob;
import net.sf.hibernate.*;
import oracle.sql.*;
import java.io.*;
public class TestCatHibernate {
public static void testBlob() {
Session s = null ;
byte [] buffer = new byte [ 1 ];
buffer[ 0 ] = 1 ;
try {
SessionFactory sf = HibernateSessionFactory.getSessionFactory();
s = sf.openSession();
Transaction tx = s.beginTransaction();
Cat c = new Cat();
c.setName( "Robbin" );
c.setImage(Hibernate.createBlob(buffer));
s.save(c);
s.flush();
s.refresh(c, LockMode.UPGRADE);
BLOB blob = (BLOB) c.getImage();
OutputStream out = blob.getBinaryOutputStream();
String fileName = "oraclejdbc.jar" ;
File f = new File(fileName);
FileInputStream fin = new FileInputStream(f);
int count = - 1 , total = 0 ;
byte [] data = new byte [( int )fin.available()];
fin.read(data);
out.write(data);
fin.close();
out.close();
s.flush();
tx.commit();
} catch (Exception e) {
System.out.println(e.getMessage());
} finally {
if (s != null )
try {
s.close();
} catch (Exception e) {}
}
}
}
写入Blob字段和写入其它类型字段的方式非常不同,因为Blob自身有一个cursor,你必须使用cursor对blob进行操作,因而你在写入Blob之前,必须获得cursor才能进行写入,那么如何获得Blob的cursor呢?
这需要你先插入一个empty的blob,这将创建一个blob的cursor,然后你再把这个empty的blob的cursor用select查询出来,这样通过两步操作,你就获得了blob的cursor,可以真正的写入blob数据了。
看下面的JDBC的demo,把oraclejdbc.jar这个二进制文件写入数据库表javatest的content字段(这是一个blob型字段)
代码
import java.sql.*;
import java.io.*;
import oracle.sql.*;
public class WriteBlob {
public static void main(String[] args) {
try {
DriverManager.registerDriver( new oracle.jdbc.driver.OracleDriver());
Connection conn = DriverManager.getConnection( "jdbc:oracle:thin:@localhost:1521:orcl" , "fankai" , "fankai" );
conn.setAutoCommit( false );
BLOB blob = null ;
PreparedStatement pstmt = conn.prepareStatement( "insert into javatest(name,content) values(?,empty_blob())" );
pstmt.setString( 1 , "fankai" );
pstmt.executeUpdate();
pstmt.close();
pstmt = conn.prepareStatement( "select content from javatest where name= ? for update" );
pstmt.setString( 1 , "fankai" );
ResultSet rset = pstmt.executeQuery();
if (rset.next()) blob = (BLOB) rset.getBlob( 1 );
String fileName = "oraclejdbc.jar" ;
File f = new File(fileName);
FileInputStream fin = new FileInputStream(f);
System.out.println( "file size = " + fin.available());
pstmt = conn.prepareStatement( "update javatest set content=? where name=?" );
OutputStream out = blob.getBinaryOutputStream();
int count = - 1 , total = 0 ;
byte [] data = new byte [( int )fin.available()];
fin.read(data);
out.write(data);
/*
byte[] data = new byte[blob.getBufferSize()]; 另一种实现方法,节省内存
while ((count = fin.read(data)) != -1) {
total += count;
out.write(data, 0, count);
}
*/
fin.close();
out.close();
pstmt.setBlob( 1 ,blob);
pstmt.setString( 2 , "fankai" );
pstmt.executeUpdate();
pstmt.close();
conn.commit();
conn.close();
} catch (SQLException e) {
System.err.println(e.getMessage());
e.printStackTrace();
} catch (IOException e) {
System.err.println(e.getMessage());
}
}
}
仔细看上例,分三步:
1、插入空blob
into javatest(name,content) values(?,empty_blob());
2、获得blob的cursor
select content from javatest where name= ? for update;
注意!!!必须加for update,这将锁定该行,直至该行被修改完毕,保证不产生并发冲突。
3、update javatest set content=? where name=
用cursor往数据库写数据
这里面还有一点要提醒大家:
JDK1.3带的JDBC2.0规范是不完善的,只有读Blob的接口,而没有写Blob的接口,JDK1.4带的JDBC3.0加入了写Blob的接口。你可以使用JDBC3.0的接口,也可以直接使用Oracle的JDBC的API,我在上例中使用了Oracle的JDBC的API。
另外要注意的是:
java.sql.Blob
oracle.sql.BLOB
注意看blob的大小写,是不一样的。写程序的时候不要搞混了。
下面看看用Hibernate怎么写,原理是一样的,也要分三步,但是代码简单很多
这是Cat对象定义
代码
package com.fankai;
import java.sql.Blob;
public class Cat {
private String id;
private String name;
private char sex;
private float weight;
private Blob image;
public Cat() { }
public String getId() { return id; }
public void setId(String id) { this .id = id; }
public String getName() { return name; }
public void setName(String name) { this .name = name; }
public char getSex() { return sex; }
public void setSex( char sex) { this .sex = sex; }
public float getWeight() { return weight; }
public void setWeight( float weight) { this .weight = weight; }
public Blob getImage() { return image; }
public void setImage(Blob image) { this .image = image;}
}
这是Cat.hbm.xml
代码
<? xml version = "1.0" ?>
<!DOCTYPE hibernate-mapping SYSTEM "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" >
< hibernate-mapping >
< class name = "com.fankai.Cat" table = "cat" >
<!--jcs-cache usage="read-only"/-->
< id name = "id" unsaved-value = "null" >
< generator class = "uuid.hex" />
</ id >
< property name = "name" length = "16" not-null = "true" />
< property name = "sex" length = "1" not-null = "true" />
< property name = "weight" />
< property name = "image" />
</ class >
</ hibernate-mapping >
下面是完整的用Hibernate写入Blob的例子,相比JDBC,已经简单轻松多了,也不用写那些Oracle特殊的sql了:
代码
package com.fankai;
import java.sql.Blob;
import net.sf.hibernate.*;
import oracle.sql.*;
import java.io.*;
public class TestCatHibernate {
public static void testBlob() {
Session s = null ;
byte [] buffer = new byte [ 1 ];
buffer[ 0 ] = 1 ;
try {
SessionFactory sf = HibernateSessionFactory.getSessionFactory();
s = sf.openSession();
Transaction tx = s.beginTransaction();
Cat c = new Cat();
c.setName( "Robbin" );
c.setImage(Hibernate.createBlob(buffer));
s.save(c);
s.flush();
s.refresh(c, LockMode.UPGRADE);
BLOB blob = (BLOB) c.getImage();
OutputStream out = blob.getBinaryOutputStream();
String fileName = "oraclejdbc.jar" ;
File f = new File(fileName);
FileInputStream fin = new FileInputStream(f);
int count = - 1 , total = 0 ;
byte [] data = new byte [( int )fin.available()];
fin.read(data);
out.write(data);
fin.close();
out.close();
s.flush();
tx.commit();
} catch (Exception e) {
System.out.println(e.getMessage());
} finally {
if (s != null )
try {
s.close();
} catch (Exception e) {}
}
}
}
相关文章推荐
- JDBC+Hibernate将Blob数据写入Oracle
- JDBC+Hibernate将Blob数据写入Oracle
- 用JDBC和Hibernate来写入Blob型数据到Oracle中
- JDBC+Hibernate将Blob数据写入Oracle
- 使用JDBC和Hibernate来写入Blob型数据到Oracle中
- JDBC+Hibernate将Blob数据写入Oracle
- 使用JDBC和Hibernate来写入Blob型数据到Oracle中
- JDBC+Hibernate将Blob数据写入Oracle
- JDBC+Hibernate将Blob数据写入Oracle
- JDBC+Hibernate将Blob数据写入Oracle
- 使用JDBC和Hibernate来写入Blob型数据到Oracle中
- JDBC+Hibernate将Blob数据写入Oracle
- 使用JDBC和Hibernate来写入Blob型数据到Oracle中
- JDBC+Hibernate将Blob数据写入Oracle
- JDBC+Hibernate将Blob数据写入Oracle
- 使用JDBC和Hibernate来写入Blob型数据到Oracle中
- JDBC+Hibernate将Blob数据写入Oracle
- Jdbc/Hibernate连接Oracle 、 MySQL
- clob字段只能写入4k内容,超过后报null at org.apache.openjpa.jdbc.sql.OracleDictionary.putString
- Oracle&JDBC&Hibernate知识总结