Generate a Captcha picture

1 Picture.java

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Package com.util;

Import Java.awt.Color;
Import Java.awt.Font;
Import Java.awt.Graphics2D;
Import Java.awt.image.BufferedImage;
Import java.io.IOException;
Import Java.io.OutputStream;
Import Java.util.Random;

Import Javax.imageio.ImageIO;

/**
* @author Ysma
* @version 1.0.0, 2012-0413
* @since 1.0
*/
public class picture
{
private static random random; Random number
private static char[] chars;//store a-z,0-9, used when generating keys randomly, minus 0 and O
private static final int length = 32;//c[] is 32

Static
{
Init ();
}

/**
* init.
*/
private static void Init ()
{
Random = new Random (System.currenttimemillis ());

chars = new Char[length];

int i = 0;
for (char b = ' A '; b <= ' Z '; b++)
{
if (b! = ' O ')
{
chars[i++] = b;
}
Else
{
i--;
}
}
for (char B = ' 0 '; b <= ' 9 '; b++)
{
if (b! = ' 0 ')
{
chars[i++] = b;
}
Else
{
i--;
}
}
}

/**
* Next.
*
* @return int
*/
public static int Nextint ()
{
return Random.nextint ();
}

/**
* Next N.
*
* @param n
* INT
* @return int
*/
public static int Nextint (int n)
{
return Random.nextint (n);
}

/**
* Generate Keylength bit random string, string containing only a-z,0-9, minus O and 0.
*
* @param keylength
* INT
* @return String
*/
public static String GenerateKey (int keylength)
{
StringBuffer buffer = new StringBuffer ();
int index;
for (int i = 0; i < keylength; i++)
{
index = Random.nextint (LENGTH);
Buffer.append (Chars[index]);
}
return buffer.tostring ();
}

/**
* Generates a 32-bit random string, and the string contains only a-z,0-9.
*
* @return String
*/
public static String GenerateKey ()
{
Return GenerateKey (integer.valueof ("32"));
}

 /**
  *
  * Output CAPTCHA image
  *
  * @param os
  *    & nbsp;       output Stream
  * @param code
  *             Verification Code on the image
  * @param width
  *             Image Width
  * @param height
  *             Image Height
  * @throws ioexception
  *              Exception
  */
 public static void Generateverifycode ( OutputStream OS, String code, int width, int height) throws IOException
 {
  bufferedimage buffimg = new BufferedImage (width, height, bufferedimage.type_int_bgr);
  graphics2d g = buffimg.creategraphics ();

G.setcolor (Color.White);
G.fillrect (0, 0, width, height);
Font font = new Font ("Times New Roma", Font.plain, integer.valueof ("18"));
G.setfont (font);

G.setcolor (Color.Black);
G.drawrect (0, 0, width-1, height-1);

G.setcolor (New Color (Integer.valueof ("192"), Integer.valueof ("192"), Integer.valueof ("192"));
int x, y, x1, y1;
for (int i = 0; I < (width + height); i++)
{
x = random.nextint (width);
y = random.nextint (height);
X1 = Random.nextint (integer.valueof ("12"));
Y1 = Random.nextint (integer.valueof ("12"));
G.drawline (x, y, x + x1, y + y1);
}

int red = 0, green = 0, blue = 0;
for (int i = 0, n = code.length (); i < n; i++)
{
Red = Random.nextint (integer.valueof ("110"));
Green = Random.nextint (integer.valueof ("110"));
Blue = Random.nextint (integer.valueof ("110"));

G.setcolor (New Color (red, green, blue));
g.DrawString (Code.charat (i) + "", integer.valueof ("+") * i + integer.valueof ("6"), integer.valueof ("16"));
}

Imageio.write (buffimg, "JPEG", OS);
Os.flush ();
}
}

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2,createimage.java

----------------------------------------------

Package com.util;

Import java.io.IOException;
Import Java.io.OutputStream;

Import javax.servlet.ServletException;
Import Javax.servlet.http.HttpServlet;
Import Javax.servlet.http.HttpServletRequest;
Import Javax.servlet.http.HttpServletResponse;
Import javax.servlet.http.HttpSession;

/**
* @author Ysma
* @version 1.0.0
* @since 2012-04-03
*/
public class CreateImage extends HttpServlet
{
public void doget (HttpServletRequest request, httpservletresponse response) throws Servletexception, IOException
{
Doprocessor (request, response);
}

public void DoPost (HttpServletRequest request, httpservletresponse response) throws Servletexception, IOException
{
Doprocessor (request, response);
}

private void Doprocessor (HttpServletRequest request, httpservletresponse response) throws Servletexception, IOException
{
HttpSession session = Request.getsession ();
Response.setheader ("Pragma", "No-cache");
Response.setheader ("Cache-control", "No-cache");
Response.setdateheader ("Expries", 0);
Response.setcontenttype ("Image/jpeg");
String code = Picture.generatekey (4); Generate 4 Random numbers

OutputStream OS = null;
Try
{
OS = Response.getoutputstream ();
Picture.generateverifycode (OS, code, 60, 20); Generate a Captcha picture
Session.setattribute ("Realcode", code);
Os.flush ();
}
catch (IOException E)
{
Throw e;
}
Finally
{
Try
{
Os.close ();
}
catch (Exception e)
{
}
}
}
}

--------------------------------------------------Big Cut----------------------------------------------------------

3. Web. XML configuration

-------------------------

<!--valid code--
<servlet>
<servlet-name>createImage</servlet-name>
<servlet-class>com.util.CreateImage</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>createImage</servlet-name>
<url-pattern>/servlet/CreateImage.jpeg</url-pattern>
</servlet-mapping>
<!--valid code end--