View Png 2 : Image « J2ME « Java
View Png 2
/*--------------------------------------------------
* ViewPng2.java
*
* Download and view a png file
*
* Same as pngView.java with the exception that the
* connection to the server is through an
* InputStream versus ContentConnection
*
* Example from the book: Core J2ME Technology
* Copyright John W. Muchow http://www.CoreJ2ME.com
* You may use/modify for any non-commercial purpose
*-------------------------------------------------*/
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.io.*;
import java.io.*;
public class ViewPng2 extends MIDlet implements CommandListener
{
private Display display;
private TextBox tbMain;
private Form fmViewPng;
private Command cmExit;
private Command cmView;
private Command cmBack;
public ViewPng2()
{
display = Display.getDisplay(this);
// Create the Main textbox with a maximum of 75 characters
tbMain = new TextBox("Enter url", "http://www.corej2me.com/midpbook_v1e1/ch14/duke.png", 75, 0);
// Create commands and add to textbox
cmExit = new Command("Exit", Command.EXIT, 1);
cmView = new Command("View", Command.SCREEN, 2);
tbMain.addCommand(cmExit);
tbMain.addCommand(cmView );
// Set up a listener for textbox
tbMain.setCommandListener(this);
// ---------------------------------------
// Create the form that will hold the png image
fmViewPng = new Form("");
// Create commands and add to form
cmBack = new Command("Back", Command.BACK, 1);
fmViewPng.addCommand(cmBack);
// Set up a listener for form
fmViewPng.setCommandListener(this);
}
public void startApp()
{
display.setCurrent(tbMain);
}
public void pauseApp()
{ }
public void destroyApp(boolean unconditional)
{ }
/*--------------------------------------------------
* Process events
*-------------------------------------------------*/
public void commandAction(Command c, Displayable s)
{
// If the Command button pressed was "Exit"
if (c == cmExit)
{
destroyApp(false);
notifyDestroyed();
}
else if (c == cmView)
{
// Delete everything from the form
if (fmViewPng.size() > 0)
for (int i = 0; i < fmViewPng.size(); i++)
fmViewPng.delete(i);
// Download image and set as the first (only) item on the form
Image im;
try
{
if ((im = getImage(tbMain.getString())) != null)
{
ImageItem ii = new ImageItem(null, im, ImageItem.LAYOUT_DEFAULT, null);
// If there is already an image, set (replace) it
if (fmViewPng.size() != 0)
fmViewPng.set(0, ii);
else // Append the image to the empty form
fmViewPng.append(ii);
}
else
fmViewPng.append("Unsuccessful download.");
// Display the form with the image
display.setCurrent(fmViewPng);
}
catch (Exception e)
{
System.err.println("Msg: " + e.toString());
}
}
else if (c == cmBack) {
display.setCurrent(tbMain);
}
}
/*--------------------------------------------------
* Open connection and download png into a byte array.
*-------------------------------------------------*/
private Image getImage(String url) throws IOException
{
InputStream iStrm = (InputStream) Connector.openInputStream(url);
Image im = null;
try
{
ByteArrayOutputStream bStrm = new ByteArrayOutputStream();
int ch;
while ((ch = iStrm.read()) != -1)
bStrm.write(ch);
// Place into image array
byte imageData[] = bStrm.toByteArray();
// Create the image from the byte array
im = Image.createImage(imageData, 0, imageData.length);
}
finally
{
// Clean up
if (iStrm != null)
iStrm.close();
}
return (im == null ? null : im);
}
}
