The technique of realizing picture verification code in JSP

Picture Verification Code implementation The main technical point is how to generate a picture. The build picture can be implemented using the classes under the java.awt package. Let's write a simple program to generate a picture Helloimage.java. Here is the code section.

Package com.vogoal.test;
Import Java.awt.Color;
Import Java.awt.Graphics;
Import Java.awt.image.BufferedImage;
Import Java.io.File;
Import java.io.IOException;
Import Javax.imageio.ImageIO;
/**

* Create a image
*/
public class Helloimage {
    public static void Main (string[] args) {
        BufferedImage image = New BufferedImage (80, 25,
                BUFFEREDIMAGE.TYPE_INT_RGB);
        Graphics g = image.getgraphics ();
        G.setcolor (New Color (255,255,255));
        G.fillrect (0, 0, 80, 25);
        G.setcolor (New Color (0,0,0));
        g.DrawString ("Helloimage", 6,16);
        G.dispose ();
        try{
            Imageio.write (image, "JPEG", New File ("C:\\helloimage.jpeg"));
        }catch (IOException e) {
            E.printstacktrace ();
        }
    }
}

After compiling, in DOS down use this program, under normal circumstances, will be in the C packing directory to generate a name helloimage.jpeg for the picture. There are text helloimage in the picture.

A brief introduction to the process of generating pictures:

1. Establish the BufferedImage object. Specifies the width and color of the picture's length.

BufferedImage image = new BufferedImage (80,25,BUFFEREDIMAGE.TYPE_INT_RGB);

2. Get the Graphics object to draw the picture.

Graphics g = image.getgraphics ();

3. Draw picture background and text.

4. Release the resources occupied by the Graphics object.

G.dispose ();

5. Output the picture through the write static method of the ImageIO object.

Imageio.write (image, "JPEG", New File ("C:\\helloimage.jpeg"));