Help please..Java net

[ben1967]

Hi All,

Kindly let me know how to down load an image in a web page to an Image
Object by a Java application .Example " logo.gif" of this page.

Many thanks in advance
ben1967

[sjalle]

Here is an application that requires you to enter the image url. You find that by right clicking the image ->properties. The key class is the SiteConn class.
This class can also download the entire web page (getContents()), then you may use the Http parser utilities in java to disect the page completely

import javax.swing.*;

/**
 * Get an image from the net
 */

import java.net.*;
import java.io.*;
import java.awt.*;
import java.awt.event.*;
/**
 * Application frame
 */
public class ImageGrabber extends JFrame implements ActionListener {
  BorderLayout borderLayout1 = new BorderLayout();
  ImagePan imgPan = new ImagePan();
  JPanel jPanel2 = new JPanel();
  BorderLayout borderLayout2 = new BorderLayout();
  JButton getBtn = new JButton();
  JTextField urlTF = new JTextField();

  public ImageGrabber() {
    try {
      jbInit();
      getBtn.addActionListener(this); // hook up button
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }
  public static void main(String[] args) {
    ImageGrabber imageGrabber = new ImageGrabber();
    imageGrabber.addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    });
    imageGrabber.setBounds(20,20, 500,400);
    imageGrabber.setVisible(true);
  }
  /**
   * Initialize the application
   */
  private void jbInit() throws Exception {
    this.getContentPane().setLayout(borderLayout1);
    jPanel2.setLayout(borderLayout2);
    getBtn.setText("Get Image");
    urlTF.setText("http://");
    this.getContentPane().add(imgPan, BorderLayout.CENTER);
    this.getContentPane().add(jPanel2, BorderLayout.SOUTH);
    jPanel2.add(getBtn, BorderLayout.WEST);
    jPanel2.add(urlTF, BorderLayout.CENTER);
  }
  /**
   * Get url string, retrieve image bytes, create image and display it
   * @param e
   */
  public void actionPerformed(ActionEvent e) {
    try {
      String urlStr = urlTF.getText().trim();
      URL url = new URL(urlStr);
      SiteConn aConnection = new SiteConn(url);
      byte[] b = aConnection.getByteBuffer();
      Image img = Toolkit.getDefaultToolkit().createImage(b);
      imgPan.setImage(img);
    }
    catch (Exception ex) {
      ex.printStackTrace();
    }
  }
}
/* a very basic image display panel */
class ImagePan extends JPanel {
  private Image img=null;

  public void setImage(Image img) {
    this.img=img;
    repaint();
  }
  public void paintComponent(Graphics g) {
    Color c=g.getColor();
    g.setColor(Color.white);
    g.fillRect(0,0,getWidth(), getHeight());
    if (img==null) {
      g.setColor(Color.black);
      g.drawString("No image loaded yet", 20, 20);
    } else {
      g.drawImage(img, 0,0,this);
    }
    g.setColor(c);
  }
}

/** SITECONN
Usage example:
try {
  URL url=new URL("http://www.whatever.com/servlets/store?text=storeThisTExt");
  SiteConn aConnection=new SiteConn(url);
  StringBuffer sb=aConnection.getContens();
  System.out.println(sb.toString());
} catch (MalFormedURLException mfe) {
  System.err.println(mfe.getMessage());
}
 *
 */

class SiteConn {
  URL url=null;
  public SiteConn(URL  url) {
    this.url=url;
  }
  public StringBuffer getContents() throws Exception {
    StringBuffer buffer;
    String line;
    int responseCode;
    HttpURLConnection connection;

    BufferedReader dataInput;
    connection = (HttpURLConnection)url.openConnection();
    responseCode = connection.getResponseCode();
    if (responseCode != HttpURLConnection.HTTP_OK) {
      throw new Exception("HTTP response code: " +
         String.valueOf(responseCode));
    }
    try {
      buffer = new StringBuffer();
      InputStream input = connection.getInputStream();
      dataInput = new BufferedReader(new InputStreamReader(input));

      while ( (line = dataInput.readLine()) != null) {
        buffer.append(line);
        buffer.append('\n');
        //System.out.println("line: " + line);
      }
      input.close();
    } catch (Exception ex) {
      ex.printStackTrace(System.err);
      return null;
    }
   return buffer;
  }
  public byte [] getByteBuffer () throws Exception {

    String line;
    int responseCode;
    HttpURLConnection connection;


    connection = (HttpURLConnection)url.openConnection();
    InputStream input=connection.getInputStream();

    responseCode = connection.getResponseCode();

    if (responseCode != HttpURLConnection.HTTP_OK) {
      throw new Exception("HTTP response code: " +
         String.valueOf(responseCode));
    }

    try {
      byte [] b=new byte[1420];
      BufferedInputStream in=new BufferedInputStream(input);
      ByteArrayOutputStream out=new ByteArrayOutputStream();
      //System.out.println("starting");
      int n=in.read(b);
      //System.out.println("start:"+n);
      while (n  > 0) {
        out.write(b,0,n);
        n=in.read(b);
        //System.out.println("buf:"+n);
      }
      out.close();
      input.close();
      return out.toByteArray();
    } catch (Exception ex) {
      ex.printStackTrace(System.err);
      return null;
    }

  }

}

[ben1967]

Here is an application that requires you to enter the image url. You find that by right clicking the image ->properties. The key class is the SiteConn class.
This class can also download the entire web page (getContents()), then you may use the Http parser utilities in java to disect the page completely

import javax.swing.*;

/**
 * Get an image from the net
 */

import java.net.*;
import java.io.*;
import java.awt.*;
import java.awt.event.*;
/**
 * Application frame
 */
public class ImageGrabber extends JFrame implements ActionListener {
  BorderLayout borderLayout1 = new BorderLayout();
  ImagePan imgPan = new ImagePan();
  JPanel jPanel2 = new JPanel();
  BorderLayout borderLayout2 = new BorderLayout();
  JButton getBtn = new JButton();
  JTextField urlTF = new JTextField();

  public ImageGrabber() {
    try {
      jbInit();
      getBtn.addActionListener(this); // hook up button
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }
  public static void main(String[] args) {
    ImageGrabber imageGrabber = new ImageGrabber();
    imageGrabber.addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    });
    imageGrabber.setBounds(20,20, 500,400);
    imageGrabber.setVisible(true);
  }
  /**
   * Initialize the application
   */
  private void jbInit() throws Exception {
    this.getContentPane().setLayout(borderLayout1);
    jPanel2.setLayout(borderLayout2);
    getBtn.setText("Get Image");
    urlTF.setText("http://");
    this.getContentPane().add(imgPan, BorderLayout.CENTER);
    this.getContentPane().add(jPanel2, BorderLayout.SOUTH);
    jPanel2.add(getBtn, BorderLayout.WEST);
    jPanel2.add(urlTF, BorderLayout.CENTER);
  }
  /**
   * Get url string, retrieve image bytes, create image and display it
   * @param e
   */
  public void actionPerformed(ActionEvent e) {
    try {
      String urlStr = urlTF.getText().trim();
      URL url = new URL(urlStr);
      SiteConn aConnection = new SiteConn(url);
      byte[] b = aConnection.getByteBuffer();
      Image img = Toolkit.getDefaultToolkit().createImage(b);
      imgPan.setImage(img);
    }
    catch (Exception ex) {
      ex.printStackTrace();
    }
  }
}
/* a very basic image display panel */
class ImagePan extends JPanel {
  private Image img=null;

  public void setImage(Image img) {
    this.img=img;
    repaint();
  }
  public void paintComponent(Graphics g) {
    Color c=g.getColor();
    g.setColor(Color.white);
    g.fillRect(0,0,getWidth(), getHeight());
    if (img==null) {
      g.setColor(Color.black);
      g.drawString("No image loaded yet", 20, 20);
    } else {
      g.drawImage(img, 0,0,this);
    }
    g.setColor(c);
  }
}

/** SITECONN
Usage example:
try {
  URL url=new URL("http://www.whatever.com/servlets/store?text=storeThisTExt");
  SiteConn aConnection=new SiteConn(url);
  StringBuffer sb=aConnection.getContens();
  System.out.println(sb.toString());
} catch (MalFormedURLException mfe) {
  System.err.println(mfe.getMessage());
}
 *
 */

class SiteConn {
  URL url=null;
  public SiteConn(URL  url) {
    this.url=url;
  }
  public StringBuffer getContents() throws Exception {
    StringBuffer buffer;
    String line;
    int responseCode;
    HttpURLConnection connection;

    BufferedReader dataInput;
    connection = (HttpURLConnection)url.openConnection();
    responseCode = connection.getResponseCode();
    if (responseCode != HttpURLConnection.HTTP_OK) {
      throw new Exception("HTTP response code: " +
         String.valueOf(responseCode));
    }
    try {
      buffer = new StringBuffer();
      InputStream input = connection.getInputStream();
      dataInput = new BufferedReader(new InputStreamReader(input));

      while ( (line = dataInput.readLine()) != null) {
        buffer.append(line);
        buffer.append('\n');
        //System.out.println("line: " + line);
      }
      input.close();
    } catch (Exception ex) {
      ex.printStackTrace(System.err);
      return null;
    }
   return buffer;
  }
  public byte [] getByteBuffer () throws Exception {

    String line;
    int responseCode;
    HttpURLConnection connection;


    connection = (HttpURLConnection)url.openConnection();
    InputStream input=connection.getInputStream();

    responseCode = connection.getResponseCode();

    if (responseCode != HttpURLConnection.HTTP_OK) {
      throw new Exception("HTTP response code: " +
         String.valueOf(responseCode));
    }

    try {
      byte [] b=new byte[1420];
      BufferedInputStream in=new BufferedInputStream(input);
      ByteArrayOutputStream out=new ByteArrayOutputStream();
      //System.out.println("starting");
      int n=in.read(b);
      //System.out.println("start:"+n);
      while (n  > 0) {
        out.write(b,0,n);
        n=in.read(b);
        //System.out.println("buf:"+n);
      }
      out.close();
      input.close();
      return out.toByteArray();
    } catch (Exception ex) {
      ex.printStackTrace(System.err);
      return null;
    }

  }

}

Dear sjalle,

Thank you .
This code serves my purpose. Infact you gave me more than what I wanted.

ben1967