在java应用程序中显示数据库的blob图像


原理: 
<1> 从数据库中读取blob到Blob对象. Blob blob = rs.getBlob(2);  
<2>把blob传给Stream. 
<3>用Stream参数创建Image对象 
<4>显示Image对象. 
说明: 这只是例子, 没有考虑其他方面. 希望大家能对java连接数据库,和取对象有个具体的了解. 
关于数据库的sql 
CREATE TABLE photo ( 
photo_no int(6) unsigned NOT NULL auto_increment, 
image blob, 
PRIMARY KEY (`photo_no`) 
)  
本例子用到两个文件: 
DrawPanel.java如下 
import java.awt.*; 
import java.sql.*; 
import java.awt.image.*; 
import java.io.*; 
import javax.swing.*; 
/** 
* <p>Title: </p> 
* 
* <p>Description:vincentlaw@163.com </p> 
* 
* <p>Copyright: Copyright (c) 2005</p> 
* 
* <p>Vincent</p> 
* 
* @author vincent 
* @version 1.0 
*/ 
public class DrawPanel extends Panel { 
Image im; 
Insets insets; 
public DrawPanel() { 
im=Toolkit.getDefaultToolkit().getImage("c:1.jpg"); //默认的文件  
try { 
jbInit(); 
} catch (Exception ex) { 
ex.printStackTrace(); 
} 
} 
public void addNotify() { 
super.addNotify();  
insets = getInsets(); 
setBounds(100, 100, 217 + insets.left, 321 + insets.top); 
} 
public void paint(Graphics g) { 
g.drawImage(im, insets.left, insets.top, this); 
} 
private void jbInit() throws Exception { 
} 
public void changeImage(String fileName) 
{ 
try { 
//Class.forName("oracle.jdbc.driver.OracleDriver"); 
//Connection conn = DriverManager.getConnection("jdbc:oracle:thin:@127.0.0.1:1521:orcl2", "user","password"); 
Class.forName("com.mysql.jdbc.Driver"); 
Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/job?user=root&password=5672831"); 
Statement stmt = conn.createStatement(); 
ResultSet rs = stmt.executeQuery("select photo_no,photo_image from photo"); 
rs.next(); 
Blob blob = rs.getBlob(2); 
// 数据库连接 
InputStream fin = blob.getBinaryStream(); 
im = javax.imageio.ImageIO.read(fin); 
rs.close(); 
stmt.close(); 
conn.close(); 
} 
catch(Exception e) 
{ 
e.printStackTrace(); 
JOptionPane.showMessageDialog(null,"错误,装载本地文件"); 
im=Toolkit.getDefaultToolkit().getImage(fileName); 
} 
this.repaint(); 
} 
} 
ShowImage.java如下: 
import java.awt.BorderLayout; 
import java.awt.*; 
import javax.swing.*; 
import javax.swing.JToggleButton; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 
/** 
* <p>Title: </p> 
* 
* <p>Description:vincentlaw@163.com </p> 
* 
* <p>Copyright: Copyright (c) 2005</p> 
* 
* <p>Vincent</p> 
* 
* @author vincent 
* @version 1.0 
*/ 
public class ShowImage extends JFrame { 
BorderLayout borderLayout1 = new BorderLayout(); 
JToggleButton jToggleButton1 = new JToggleButton(); 
DrawPanel panel=new DrawPanel(); 
public ShowImage() { 
try { 
jbInit(); 
} catch (Exception exception) { 
exception.printStackTrace(); 
} 
} 
private void jbInit() throws Exception { 
getContentPane().setLayout(borderLayout1); 
jToggleButton1.setText("jToggleButton1"); 
jToggleButton1.addActionListener(new 
ShowImage_jToggleButton1_actionAdapter(this)); 
this.getContentPane().add(jToggleButton1, java.awt.BorderLayout.NORTH); 
this.getContentPane().add(panel,java.awt.BorderLayout.CENTER); 
} 
public void jToggleButton1_actionPerformed(ActionEvent e) { 
panel.changeImage("E:photohoto1281.jpg"); //备用图像文件 
} 
public final static void main(String[] args){ 
JFrame frame=new ShowImage(); 
frame.setSize(800,600); 
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
frame.setVisible(true); 
} 
} 
class ShowImage_jToggleButton1_actionAdapter implements ActionListener { 
private ShowImage adaptee; 
ShowImage_jToggleButton1_actionAdapter(ShowImage adaptee) { 
this.adaptee = adaptee; 
} 
public void actionPerformed(ActionEvent e) { 
adaptee.jToggleButton1_actionPerformed(e); 
} 
}

补充：软件开发 , Java ,