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Oops...missed over half the patch :(
This commit is contained in:
Marc G. Fournier
377
src/interfaces/jdbc/example/ImageViewer.java
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377
src/interfaces/jdbc/example/ImageViewer.java
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@ -0,0 +1,377 @@
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package example;
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import java.awt.*;
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import java.awt.event.*;
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import java.io.*;
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import java.sql.*;
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import postgresql.largeobject.*;
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/**
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* This example is a small application that stores and displays images
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* held on a postgresql database.
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*
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* Before running this application, you need to create a database, and
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* on the first time you run it, select "Initialise" in the "PostgreSQL"
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* menu.
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*
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* Important note: You will notice we import the postgresql.largeobject
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* package, but don't import the postgresql package. The reason for this is
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* that importing postgresql can confuse javac (we have conflicting class names
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* in postgresql.* and java.sql.*). This doesn't cause any problems, as long
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* as no code imports postgresql.
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*
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* Under normal circumstances, code using any jdbc driver only needs to import
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* java.sql, so this isn't a problem.
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*
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* It's only if you use the non jdbc facilities, do you have to take this into
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* account.
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*
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*/
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public class ImageViewer implements ItemListener
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{
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Connection db;
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Statement stat;
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LargeObjectManager lom;
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Frame frame;
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Label label; // Label used to display the current name
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List list; // The list of available images
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imageCanvas canvas; // Canvas used to display the image
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String currentImage; // The current images name
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// This is a simple component to display our image
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public class imageCanvas extends Canvas
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{
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private Image image;
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public imageCanvas()
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{
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image=null;
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}
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public void setImage(Image img)
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{
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image=img;
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repaint();
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}
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// This defines our minimum size
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public Dimension getMinimumSize()
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{
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return new Dimension(400,400);
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}
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public Dimension getPreferedSize()
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{
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return getMinimumSize();
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}
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public void update(Graphics g)
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{
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paint(g);
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}
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public void paint(Graphics g)
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{
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g.setColor(Color.gray);
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g.fillRect(0,0,getSize().width,getSize().height);
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if(image!=null)
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g.drawImage(image,0,0,this);
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}
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}
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public ImageViewer(Frame f,String url,String user,String password) throws ClassNotFoundException, FileNotFoundException, IOException, SQLException
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{
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frame = f;
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MenuBar mb = new MenuBar();
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Menu m;
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MenuItem i;
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f.setMenuBar(mb);
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mb.add(m = new Menu("PostgreSQL"));
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m.add(i= new MenuItem("Initialise"));
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i.addActionListener(new ActionListener() {
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public void actionPerformed(ActionEvent e) {
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ImageViewer.this.init();
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}
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});
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m.add(i= new MenuItem("Exit"));
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ActionListener exitListener = new ActionListener() {
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public void actionPerformed(ActionEvent e) {
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ImageViewer.this.close();
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}
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};
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m.addActionListener(exitListener);
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mb.add(m = new Menu("Image"));
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m.add(i= new MenuItem("Import"));
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ActionListener importListener = new ActionListener() {
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public void actionPerformed(ActionEvent e) {
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ImageViewer.this.importImage();
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}
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};
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i.addActionListener(importListener);
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m.add(i= new MenuItem("Remove"));
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ActionListener removeListener = new ActionListener() {
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public void actionPerformed(ActionEvent e) {
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ImageViewer.this.removeImage();
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}
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};
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i.addActionListener(removeListener);
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// To the north is a label used to display the current images name
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f.add("North",label = new Label());
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// We have a panel to the south of the frame containing the controls
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Panel p = new Panel();
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p.setLayout(new FlowLayout());
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Button b;
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p.add(b=new Button("Refresh List"));
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b.addActionListener(new ActionListener() {
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public void actionPerformed(ActionEvent e) {
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ImageViewer.this.refreshList();
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}
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});
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p.add(b=new Button("Import new image"));
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b.addActionListener(importListener);
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p.add(b=new Button("Remove image"));
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b.addActionListener(removeListener);
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p.add(b=new Button("Quit"));
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b.addActionListener(exitListener);
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f.add("South",p);
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// And a panel to the west containing the list of available images
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f.add("West",list=new List());
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list.addItemListener(this);
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// Finally the centre contains our image
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f.add("Center",canvas = new imageCanvas());
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// Load the driver
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Class.forName("postgresql.Driver");
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// Connect to database
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System.out.println("Connecting to Database URL = " + url);
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db = DriverManager.getConnection(url, user, password);
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// Create a statement
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stat = db.createStatement();
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// Also, get the LargeObjectManager for this connection
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lom = ((postgresql.Connection)db).getLargeObjectAPI();
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// Now refresh the image selection list
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refreshList();
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}
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/**
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* This method initialises the database by creating a table that contains
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* the image names, and Large Object OID's
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*/
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public void init()
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{
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try {
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stat.executeUpdate("create table images (imgname name,imgoid oid)");
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label.setText("Initialised database");
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} catch(SQLException ex) {
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label.setText(ex.toString());
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}
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}
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/**
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* This closes the connection, and ends the application
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*/
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public void close()
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{
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try {
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db.close();
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} catch(SQLException ex) {
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System.err.println(ex.toString());
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}
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System.exit(0);
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}
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/**
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* This imports an image into the database.
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*
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* This is the most efficient method, using the large object extension.
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*/
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public void importImage()
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{
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FileDialog d = new FileDialog(frame,"Import Image",FileDialog.LOAD);
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d.setVisible(true);
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String name = d.getFile();
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String dir = d.getDirectory();
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d.dispose();
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// Now the real import stuff
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if(name!=null && dir!=null) {
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try {
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System.out.println("Importing file");
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// A temporary buffer - this can be as large as you like
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byte buf[] = new byte[2048];
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// Open the file
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System.out.println("Opening file "+dir+"/"+name);
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FileInputStream fis = new FileInputStream(new File(dir,name));
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// Gain access to large objects
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System.out.println("Gaining LOAPI");
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// Now create the large object
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System.out.println("creating blob");
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int oid = lom.create();
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System.out.println("Opening "+oid);
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LargeObject blob = lom.open(oid);
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// Now copy the file into the object.
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//
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// Note: we dont use write(buf), as the last block is rarely the same
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// size as our buffer, so we have to use the amount read.
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System.out.println("Importing file");
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int s,t=0;
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while((s=fis.read(buf,0,buf.length))>0) {
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System.out.println("Block s="+s+" t="+t);t+=s;
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blob.write(buf,0,s);
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}
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// Close the object
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System.out.println("Closing blob");
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blob.close();
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// Now store the entry into the table
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stat.executeUpdate("insert into images values ('"+name+"',"+oid+")");
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stat.close();
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// Finally refresh the names list, and display the current image
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refreshList();
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displayImage(name);
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} catch(Exception ex) {
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label.setText(ex.toString());
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}
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}
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}
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/**
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* This refreshes the list of available images
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*/
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public void refreshList()
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{
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try {
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// First, we'll run a query, retrieving all of the image names
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ResultSet rs = stat.executeQuery("select imgname from images order by imgname");
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if(rs!=null) {
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list.removeAll();
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while(rs.next())
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list.addItem(rs.getString(1));
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rs.close();
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}
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} catch(SQLException ex) {
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label.setText(ex.toString()+" Have you initialised the database?");
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}
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}
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/**
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* This removes an image from the database
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*
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* Note: With postgresql, this is the only way of deleting a large object
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* using Java.
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*/
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public void removeImage()
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{
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try {
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// Delete any large objects for the current name
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ResultSet rs = stat.executeQuery("select imgoid from images where imgname='"+currentImage+"'");
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if(rs!=null) {
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// Even though there should only be one image, we still have to
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// cycle through the ResultSet
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while(rs.next()) {
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System.out.println("Got oid "+rs.getInt(1));
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lom.delete(rs.getInt(1));
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System.out.println("Import complete");
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}
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}
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rs.close();
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// Finally delete any entries for that name
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stat.executeUpdate("delete from images where imgname='"+currentImage+"'");
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label.setText(currentImage+" deleted");
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currentImage=null;
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refreshList();
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} catch(SQLException ex) {
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label.setText(ex.toString());
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}
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}
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/**
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* This displays an image from the database.
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*
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* For images, this is the easiest method.
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*/
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public void displayImage(String name)
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{
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try {
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System.out.println("Selecting oid for "+name);
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ResultSet rs = stat.executeQuery("select imgoid from images where imgname='"+name+"'");
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if(rs!=null) {
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// Even though there should only be one image, we still have to
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// cycle through the ResultSet
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while(rs.next()) {
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System.out.println("Got oid "+rs.getInt(1));
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canvas.setImage(canvas.getToolkit().createImage(rs.getBytes(1)));
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System.out.println("Import complete");
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label.setText(currentImage = name);
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}
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}
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rs.close();
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} catch(SQLException ex) {
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label.setText(ex.toString());
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}
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}
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public void itemStateChanged(ItemEvent e) {
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displayImage(list.getItem(((Integer)e.getItem()).intValue()));
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}
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/**
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* This is the command line instructions
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*/
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public static void instructions()
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{
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System.err.println("java example.ImageViewer jdbc-url user password");
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System.err.println("\nExamples:\n");
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System.err.println("java -Djdbc.driver=postgresql.Driver example.ImageViewer jdbc:postgresql:test postgres password\n");
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System.err.println("This example tests the binary large object api of the driver.\nBasically, it will allow you to store and view images held in the database.");
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System.err.println("Note: If you are running this for the first time on a particular database,\nyou have to select \"Initialise\" in the \"PostgreSQL\" menu.\nThis will create a table used to store image names.");
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}
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/**
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* This is the application entry point
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*/
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public static void main(String args[])
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{
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if(args.length!=3) {
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instructions();
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System.exit(1);
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}
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try {
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Frame frame = new Frame("PostgreSQL ImageViewer v6.3 rev 1");
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frame.setLayout(new BorderLayout());
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ImageViewer viewer = new ImageViewer(frame,args[0],args[1],args[2]);
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frame.pack();
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frame.setVisible(true);
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} catch(Exception ex) {
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System.err.println("Exception caught.\n"+ex);
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ex.printStackTrace();
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}
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}
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}
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