使用JDBC和Hibernate来写入Blob型数据到Oracle中
2008-11-28 17:37
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http://www.javaeye.com/topic/254
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)
Java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
Java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
Java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:
Java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); {}
}
}
}
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)
Java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(););;
}
}
}
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
Java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;}
}
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
Java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>
<?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:
Java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); {}
}
}
}
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