servlet代码，代码内容写入session sRand中：
servlet代码，代码内容写入session sRand中：
package CMCC;
import java.io.*;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.GraphicsEnvironment;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;
import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageWriter;
import javax.imageio.plugins.jpeg.JPEGImageWriteParam;
import javax.imageio.stream.ImageOutputStream;
import javax.servlet.*;
import javax.servlet.http.*;
/**
*
* @author vLua
* TODO
* 2004-12-22 16:02:52
*/
public class VerifyCodeServlet extends HttpServlet
{
private static final int IMAGE_WIDTH = 48;
private static final int IMAGE_HEIGHT = 18;
private static final int FONT_HEIGHT = 16;
private static final String SVG_SOURCE1 = "<!DOCTYPE svg PUBLIC \"-//W3C//DTD SVG 1.0//EN\" \"http://www.w3.org/TR/2001/REC-SVG-20010904/DTD/svg10.dtd\">"
+ "<svg width=\""
+ IMAGE_WIDTH
+ "\" height=\""
+ IMAGE_HEIGHT
+ "\" xmlns=\"http://www.w3.org/2000/svg\">"
+ "<text x=\"0\" y=\""
+ IMAGE_HEIGHT
+ "\" font-family=\"Arial\" font-size=\""
+ IMAGE_HEIGHT + "\" fill=\"black\">";
private static final String SVG_SOURCE2 = "</text></svg>";
/*
* If graphic environment not avaliable(eg: run under linux console), use
* svg instead of jpeg.
*/
private boolean svgMode = false;
private PrintWriter out = null;
/*
* (non-Javadoc)
*
* @see javax.servlet.http.HttpServlet#service(javax.servlet.http.HttpServletRequest,
* javax.servlet.http.HttpServletResponse)
*/
protected void service(HttpServletRequest arg0, HttpServletResponse arg1)
throws ServletException, IOException
{
if (sn == null)
return;
String vcode = sn2vcode();
arg0.getSession().setAttribute("sRand",vcode) ;//代码内容写入session中
if (svgMode)
outSVG(vcode, arg1);
else
outJPEG(vcode, arg1);
}
private void outSVG(String vcode, HttpServletResponse resp)
throws IOException
{
resp.setContentType("image/svg+xml");
resp.getOutputStream().print(SVG_SOURCE1 + vcode + SVG_SOURCE2);
}
private void outJPEG(String vcode, HttpServletResponse resp)
throws IOException
{
resp.setContentType("image/jpeg");
BufferedImage image = new BufferedImage(IMAGE_WIDTH, IMAGE_HEIGHT,
BufferedImage.TYPE_INT_RGB);
Random random = new Random();
Graphics g = image.getGraphics();
g.setColor(getRandColor(200, 250));
g.fillRect(0, 0, IMAGE_WIDTH, IMAGE_HEIGHT);
g.setFont(new Font("Times New Roman", Font.HANGING_BASELINE, 18));
g.setColor(getRandColor(160, 200));
for (int i = 0; i < 155; i++)
{
int x = random.nextInt(IMAGE_WIDTH);
int y = random.nextInt(IMAGE_HEIGHT);
int xl = random.nextInt(12);
int yl = random.nextInt(12);
g.drawLine(x, y, x + xl, y + yl);
}
for (int i = 1; i <= 4; i++)
{
String rand = vcode.substring(i - 1, i);
g.setColor(new Color(20 + random.nextInt(110), 20 + random
.nextInt(110), 20 + random.nextInt(110)));
g.drawString(rand, 13 * (i - 1) + 0, 16);
}
ImageWriter writer = (ImageWriter) ImageIO.getImageWritersByFormatName(
"jpeg").next();
JPEGImageWriteParam params = new JPEGImageWriteParam(null);
ImageOutputStream ios = ImageIO.createImageOutputStream(resp
.getOutputStream());
writer.setOutput(ios);
writer.write(null, new IIOImage(image, null, null), params);
writer.dispose();
ios.close();
}
static String sn2vcode()
{
String sRand = "";
Random random = new Random();
for (int i=0;i<4;i++)
{
String rand=String.valueOf(random.nextInt(10));
sRand+=rand;
}
return sRand;
}
/*
* (non-Javadoc)
*
* @see javax.servlet.GenericServlet#init()
*/
public void init() throws ServletException
{
try
{
GraphicsEnvironment.getLocalGraphicsEnvironment();
}
catch (Throwable e)
{
//run under linux console???
svgMode = true;
}
}
/**
* 获得随机颜色
* @param fc
* @param bc
* @return
*/
public Color getRandColor(int fc, int bc)
{
Random random = new Random();
if (fc > 255)
fc = 255;
if (bc > 255)
bc = 255;
int r = fc + random.nextInt(bc - fc);
int g = fc + random.nextInt(bc - fc);
int b = fc + random.nextInt(bc - fc);
return new Color(r, g, b);
}
}
在web.xml 中加入
<servlet>
<servlet-name>VerifyCodeServlet</servlet-name>
<servlet-class>CMCC.VerifyCodeServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>VerifyCodeServlet</servlet-name>
<url-pattern>/VerifyCodeServlet/*</url-pattern>
</servlet-mapping>
调用该servlet用http://hostname/VerifyCodeServlet/即可！
调用<img src=http://hostname/VerifyCodeServlet>
