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package com.fatcat.webchart;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.util.*;
import java.awt.image.*;
import java.awt.*;
import javax.imageio.*;
public class CodeMakerServlet extends HttpServlet
{
private Font[] codeFont =
{
new Font("Algerian", Font.BOLD, 65),
new Font("Vivaldi", Font.BOLD, 85),
new Font("Broadway", Font.BOLD, 60),
new Font("Forte", Font.BOLD, 75)
};
private Color[] color =
{
Color.BLACK, Color.RED, Color.DARK_GRAY, Color.BLUE
};
String codeNumbers = "";
int width = 250, height = 70;
// 处理 HTTP get 请求
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
// 清空缓冲区
response.reset();
// 注意这里的MIME类型
response.setContentType("image/png");
// 设置页面不缓存
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
// 创建一个 250X70 的图像
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
// 得到图形环境对象 g
Graphics g = image.getGraphics();
// 填充背景
g.setColor(Color.YELLOW);
g.fillRect(0, 0, width, height);
for (int i = 0; i < 4; i++)
{
drawCode(g, i);
}
drawNoise(g, 30);
// 绘制边框
g.setColor(Color.black);
g.drawRect(0, 0, width - 1, height - 1);
// 将验证码内容保存进session中
HttpSession session = request.getSession(true);
session.setAttribute("codeNumbers", codeNumbers);
// 重设字符串
codeNumbers = "";
// 利用ImageIO类的write方法对图像进行编码
ServletOutputStream sos = response.getOutputStream();
ImageIO.write(image, "PNG", sos);
sos.close();
}
// 绘制验证码
public void drawCode(Graphics graphics, int i)
{
int number = (int)(Math.random() * 10);
graphics.setFont(codeFont[i]);
graphics.setColor(color[i]);
graphics.drawString("" + number, 10 + i * 60, 60);
codeNumbers += number;
}
// 绘制干扰线
public void drawNoise(Graphics graphics, int lineNumber)
{
graphics.setColor(Color.YELLOW);
for (int i = 0; i < lineNumber; i++)
{
int pointX1 = 1 + (int)(Math.random() * width);
int pointY1 = 1 + (int)(Math.random() * height);
int pointX2 = 1 + (int)(Math.random() * width);
int pointY2 = 1 + (int)(Math.random() * height);
graphics.drawLine(pointX1, pointY1, pointX2, pointY2);
}
}
// 处理 HTTP post 请求, 和doGet一样
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
doGet(request, response);
}
}
以下是判断是否合法输入
package com.fatcat.webchart;
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class ValidateServlet extends HttpServlet
{
// 处理客户端提交数据的 "Post" 请求
protected void doPost(HttpServletRequest request, HttpServletResponse
response)throws ServletException, IOException
{
// 发送 XHTML 格式的页面给客户端
response.setContentType("text/html;charset=gb2312");
// 设置页面不缓存
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
// 获得用户输入的验证码
String validateCode = request.getParameter("validateCode");
// 获取保存在session中的验证码
HttpSession session = request.getSession();
String codeNumbers = (String)session.getAttribute("codeNumbers");
String url = "/JSPWeb/validate1.html";
if (codeNumbers == null)
{
response.sendRedirect(url);
return ;
}
PrintWriter out = response.getWriter();
// 开始生成 XHTML 文档
out.println("<?xml version = \"1.0\"?>");
out.println("<!DOCTYPE html PUBLIC \"-//W3C//DTD " +
"XHTML 1.0 Strict//EN\" \"http://www.w3.org" +
"/TR/xhtml1/DTD/xhtml1-strict.dtd\">");
out.println("<html xmlns = \"http://www.w3.org/1999/xhtml\">");
// 生成文档的head部分
out.println("<head>");
out.println("<title>校验认证码的Servlet</title>");
out.println("</head>");
// 生成文档的body部分
out.println("<body>");
// 校验用户输入的验证码和session中的验证码是否相同
if (codeNumbers.equals(validateCode))
{
out.println(
"<h1><font color=\"green\">输入相同,校验成功</font></h1> ");
}
else
{
out.println("<h1><font color=\"red\">输入错误,校验失败</font> <br>");
// out.println("<p>请重新<a href=\"" + url +
//"\">输入验证码</a><h1></p>");
String url2 = "/JSPWeb/validate.html";
String flag= request.getParameter("digits");
if(flag == null){
out.println("<p>请重新<a href=\"" + url +
"\">输入验证码</a><h1></p>");
}
else{
out.println("<p>请重新<a href=\"" + url2 +
"\">输入验证码</a><h1></p>");
}
}
out.println("</body>");
// 结束 XHTML 文档
out.println("</html>");
out.close(); // 关闭流
}
// 处理客户端提交数据的 "get" 请求, 和doPost一样
protected void doGet(HttpServletRequest request, HttpServletResponse
response)throws ServletException, IOException
{
doPost(request, response);
}
}
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