java验证码汇总

1.生成gif图片格式的
package com.cssweb.common.util;
import java.io.*;
import java.util.*;
import com.sun.image.codec.jpeg.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.awt.*;
import java.awt.image.*;
/*
* 功能：调用AuthServlet可以生成一个验证码图片,图片的宽度和高度可以自定义
* 调用格式: /servlet/AuthServlet?width=60&height=20
*      或者/servlet/AuthServlet
* 时间：2007-9-4
*  
*
*/
public class AuthServlet extends HttpServlet {
private static final long serialVersionUID = 8433932715396048208L;
private Font mFont=new Font("Times New Roman", Font.PLAIN,18);//设置字体
// 处理post
public void doPost(HttpServletRequest request,HttpServletResponse response)
  throws ServletException,IOException {
  doGet(request,response);
}
public void doGet(HttpServletRequest request,HttpServletResponse response)
      throws ServletException,IOException {
  // 取得一个1000-9999的随机数
  HttpSession session=request.getSession();//request.getSession(false)当参数为false时，有可能不创建session
  response.setContentType("image/gif");
  response.setHeader("Pragma","No-cache");
  response.setHeader("Cache-Control","no-cache");
  response.setDateHeader("Expires", 0);
  int width=60;
  int height=20;
  if(request.getParameter("width")!=null && !request.getParameter("width").equals(""))
   width = Integer.parseInt(request.getParameter("width"));
  if(request.getParameter("height")!=null && !request.getParameter("height").equals(""))
   height = Integer.parseInt(request.getParameter("height"));
                
     ServletOutputStream out=response.getOutputStream();
     BufferedImage i