jsp调用servlet验证码问题
我用serlvet做了一个动态生成验证码的类，请问在jsp表单中怎么调用？
我也这么做的，但是验证码图片显示不出来，我的代码：
1.web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" xmlns="http://java.
xmlns:xsi="http://www.
xsi:schemaLocation="http://java.
http://java.
<!-- servlet配置信息 -->
<servlet>
<servlet-name>YjwServlet</servlet-name>
<servlet-class>com.servlet.yjw.test.YjwServlet</servlet-class>
<init-param>
<param-name>width</param-name>
<param-value>200</param-value>
</init-param>
<init-param>
<param-name>height</param-name>
<param-value>80</param-value>
</init-param>
<init-param>
<param-name>codeCount</param-name>
<param-value>5</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>YjwServlet</servlet-name>
<url-pattern>/YjwServlet</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>
2.YjwServlet.java
package com.servlet.yjw.test;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import
import
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
/**
* 生成随机验证码
* @author yjw
*
*/
public class YjwServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
//验证码图片的宽度。
private int width=60;
//验证码图片的高度。
private int height=20;
//验证码字符个数
private int codeCount=4;
private int x=0;
//字体高度
private int fontHeight;
private int codeY;
char[] codeSequence = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };
/**
* Constructor of the object.
*/
public YjwServlet() {
super();
}
/**
* Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// response.setContentType("text/html");
// PrintWriter out = response.getWriter();
// out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
// out.println("<HTML>");
// out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
// out.println(" <BODY>");
// out.print(" This is ");
// out.print(this.getClass());
// out.println(", using the GET method");
// out.println(" </BODY>");
// out.println("</HTML>");
// out.flush();
// out.close();
request.getRequestDispatcher("index2.jsp").forward(request, response);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//定义图像buffer
BufferedImage buffImg = new BufferedImage(
width, height,BufferedImage.TYPE_INT_RGB);
Graphics2D g = buffImg.createGraphics();
//创建一个随机数生成器类
Random random = new Random();
//将图像填充为白色
g.setColor(Color.WHITE);
g.fillRect(0, 0, width, height);
//创建字体，字体的大小应该根据图片的高度来定。
Font font = new Font("Fixedsys", Font.PLAIN, fontHeight);
//设置字体。
g.setFont(font);
//画边框。
g.setColor(Color.BLACK);
g.drawRect(0, 0, width - 1, height - 1);
//随机产生160条干扰线，使图象中的认证码不易被其它程序探测到。
g.setColor(Color.BLACK);
for(int i = 0; i < 160; i++)
{
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(12);
int yl = random.nextInt(12);
g.drawLine(x, y, x + xl, y + yl);
}
//randomCode用于保存随机产生的验证码，以便用户登录后进行验证。
StringBuffer randomCode = new StringBuffer();
int red = 0, green = 0, blue = 0;
//随机产生codeCount数字的验证码。
for (int i = 0; i < codeCount; i++) {
//得到随机产生的验证码数字。
String strRand = String.valueOf(codeSequence[random.nextInt(36)]);
//产生随机的颜色分量来构造颜色值，这样输出的每位数字的颜色值都将不同。
red = random.nextInt(255);
green = random.nextInt(255);
blue = random.nextInt(255);
//用随机产生的颜色将验证码绘制到图像中。
g.setColor(new Color(red, green, blue));
g.drawString(strRand, (i + 1) * x, codeY);
//将产生的四个随机数组合在一起。
randomCode.append(strRand);
}
// 将四位数字的验证码保存到Session中。
HttpSession session = request.getSession();
session.setAttribute("validateCode", randomCode.toString());
// 禁止图像缓存。
response.setHeader("Pragma", "no-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
response.setContentType("image/jpeg");
//将图像输出到Servlet输出流中。
ServletOutputStream sos = response.getOutputStream();
ImageIO.write(buffImg, "jpeg", sos);
sos.close();
}
/**
* Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
/**
* 初始化验证图片属性
*/
public void init() throws ServletException {
//从web.xml中获取初始信息
//宽度
String strWidth=this.getInitParameter("width");
//高度
String strHeight=this.getInitParameter("height");
//字符个数
String strCodeCount=this.getInitParameter("codeCount");
//将配置的信息转换成数值
try
{
if(strWidth!=null && strWidth.length()!=0)
{
width=Integer.parseInt(strWidth);
}
if(strHeight!=null && strHeight.length()!=0)
{
height=Integer.parseInt(strHeight);
}
if(strCodeCount!=null && strCodeCount.length()!=0)
{
codeCount=Integer.parseInt(strCodeCount);
}
}
catch(NumberFormatException e)
{}
x=width/(codeCount+1);
fontHeight=height-2;
codeY=height-4;
}
}
3.index.jsp
<%@ page language="java" contentType="image/jpeg" pageEncoding="gb2312"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>My JSP 'index.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
</head>
<body>
<form name="form1">
验证码：<input type="text"><img src="YjwServlet">
</form>
</body>
</html>
很急！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！
