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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blobinto javatest(name,content) values(?,empty_blob()); 2、获得blob的cursorselect 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.Bloboracle.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<?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: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) {}
}
}
}
import java.sql.*;
import oracle.sql.*;
import java.io.*;
import oracle.jdbc.driver.OracleResultSet;public class WriteBlob {
public static void main(String[] args) {
try {
// 连接数据库
//Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
//Connection conn = DriverManager.getConnection("jdbc:odbc:Yzl","pda","pwpda");
Class.forName("oracle.jdbc.driver.OracleDriver");
Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:SISSI","pda","pwpda");
conn.setAutoCommit(false);
// 获取源照片数据
BLOB blob = null;
Blob blob2 = null;
String fileName = "c:\\01.jpg";
File f = new File(fileName);
// 先插入一条记录,用于后面获得一个Blob对象
PreparedStatement pstmt = conn.prepareStatement("insert into javatest(PICNAME,content) values(?,empty_blob())");
pstmt.setString(1,"Yzl");
pstmt.executeUpdate();
pstmt.close();
// 获得Blob对象(由于Blob是接口,不能实例化,所以只好用这种曲折方法获得)
pstmt = conn.prepareStatement("SELECT content FROM JAVATEST WHERE trim(PICNAME)=? ");
pstmt.setString(1,"Yzl");
ResultSet rset = pstmt.executeQuery();
if (rset.next()) blob = (BLOB)rset.getBlob(1);
pstmt.close();
if (blob == null){
System.out.println("blob is null");
conn.close();
return ;
}
// 填充Blob值,用于提交到数据库
FileInputStream fin = new FileInputStream(f);
System.out.println("file size = " + fin.available());
OutputStream out = blob.getBinaryOutputStream();
byte[] data = new byte[(int)fin.available()];
// 获取
fin.read(data);
out.write(data);
// 关闭资源
fin.close();
out.close();
// 插入数据库
pstmt = conn.prepareStatement("update javatest set content=? where PICNAME=?");
pstmt.setBlob(1,blob);
pstmt.setString(2,"Yzl");
pstmt.executeUpdate();
pstmt.close();
// 提交
conn.commit();
// 获取数据库中的照片
pstmt = conn.prepareStatement("SELECT content FROM JAVATEST WHERE trim(PICNAME)=? ");
pstmt.setString(1,"Yzl");
rset = pstmt.executeQuery();
if (rset.next()) blob = (BLOB)((OracleResultSet)rset).getBLOB(1);
pstmt.close();
if (blob == null){
System.out.println("blob2 is null");
conn.close();
return ;
}
// 输出到磁盘
// 获得
FileOutputStream fout = new FileOutputStream(new File("c:\\02.jpg"));
InputStream in = blob.asciiStreamValue();
data = new byte[(int)in.available()];
System.out.println("数据库中照片的字节数:"+in.available()); // 此句总是为 0 不知道为什么,有谁知道吗?
// 输出
in.read(data);
fout.write(data);
// 关闭资源
fin.close();
out.close();
conn.close();
// 打开
//Process pro = Runtime.getRuntime().exec("cmd /c start c:\\02.jpg");
} catch (SQLException e) {
System.err.println(e.getMessage());
e.printStackTrace();
} catch (IOException e) {
System.err.println(e.getMessage());
} catch(ClassNotFoundException e){
e.printStackTrace();
}
}}
// String KeyName, 用来标识要取blob的那条记录的主键的名称
// String KeyValue, 用来标识要取blob的那条记录的主键的值
// String BlobColumnName blob字段的列名
public Image readImageBlob(String TableName,
String KeyName, String KeyValue,
String BlobColumnName) throws SQLException, IOException, Exception {
Image im=null;
this._connection.setAutoCommit(false);
this._statement = _connection.createStatement();
String sql = "select " + BlobColumnName + " from " + TableName + " where " +
KeyName + "='" + KeyValue + "'";
this._resultset = this._statement.executeQuery(sql);
if(_resultset.next()){
BLOB blob = ( (OracleResultSet) _resultset).getBLOB(BlobColumnName);
InputStream inStream = blob.getBinaryStream();
JPEGImageDecoder decoderFile = JPEGCodec.createJPEGDecoder(inStream);
im = (Image) decoderFile.decodeAsBufferedImage();
inStream.close();
}
_resultset.close();
_statement.close();
return im;
}