SSH整合AJAX验证用户名存在的完整实例

package com.usc.service; /***************************** *Servlet 验证码(随机生成字母+数字的6位验证码) *@author 徐嘉伟 *QQ:858593747 *Email:auglyboy@yahoo.cn *****************************/ import java.awt.Color; import java.awt.Font; import java.awt.Graphics2D; import java.awt.GraphicsEnvironment; import java.awt.image.BufferedImage; import java.io.IOException; import java.io.OutputStream; import java.io.PrintWriter; 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; public class ImageServlet extends HttpServlet { // // /** // * Constructor of the object. // */ // public ImageServlet() { // 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 { // //明确响应文档类型是图片 // response.setContentType("image/jpeg"); //// PrintWriter outp = response.getWriter(); // //产生图片数字数组 // String code[]={ // "0","1","2","3","4","5","6","7","8","9", // "A","B","C","D","E","F","G","H","I","J", // "K","L","M","N","O","P","Q","R","S","T", // "U","V","W","S","Y","Z","a","b","c","d", // "e","f","g","h","i","j","k","l","m","n", // "o","p","q","r","s","t","u","v","w","s", // "y","z" // }; // //获得输出流 // OutputStream out=response.getOutputStream(); // //产生输出图片,具有缓存功能 // BufferedImage image=new BufferedImage(75,25,BufferedImage.TYPE_INT_RGB); // //获得绘图对象 // java.awt.Graphics g=image.getGraphics(); // //设置背景色 // //g.setColor(getRandColor(200,250)); // //g.fillRect(0, 0, width, height); // //g.setColor(java.awt.Color.WHITE); // //设置填充区域 // g.fillRect(0,0,120,70); // //设置前景颜色 // g.setColor(java.awt.Color.BLACK); // Random random = new Random(); // g.setColor(getRandColor(160,200)); // for (int i=0;i<155;i++) // { // int x = random.nextInt(75); // int y = random.nextInt(25); // int xl = random.nextInt(12); // int yl = random.nextInt(12); // g.drawLine(x,y,x+xl,y+yl); // } // //画边框 //// g.drawRect(0,0,75-1,25-1); // g.drawRect(0,0,75-1,25-1); // //设置输出信息字体 // g.setFont(new java.awt.Font("宋体",java.awt.Font.BOLD,18)); // g.setFont(new Font("Times New Roman",Font.PLAIN,18)); // //产生输出信息 ,随机产生的数字(6位) // String str=""; // for(int i=0;i<4;i++){ // //产生随机数 // //int num=(int)(Math.random()*10); // String autoStr = code[random.nextInt(62)]; // str+=autoStr; // //str+=num; //// g.setColor(getRandColor(160,200)); // g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成 // //g.drawString(str,13*i+6,16); // } //// System.out.println("生成的验证码是："+str); //// request.setAttribute("verify", str); // request.getSession().setAttribute("verify", str); // //// outp.print(str); //// System.out.println("::::"+request.getSession().getAttribute("verify")); // //输出随机数信息 // g.drawString(str,5,18); // //释放绘图对象 // g.dispose(); // //真正的输出图片到浏览器端 // javax.imageio.ImageIO.write(image,"JPEG",out); // // } // // /** // * 生成随机背景色 // * @param fc // * @param bc // * @return color // */ // private Color getRandColor(int fc,int bc){//给定范围获得随机颜色 // 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); // } // /** // * 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 { // // this.doGet(request, response); // } // // /** // * Initialization of the servlet. <br> // * // * @throws ServletException if an error occure // */ // public void init() throws ServletException { // // Put your code here // } static final long serialVersionUID = 19870121; public void init(){ /*初始化Servlet*/ } public void destory(){ /*退出Servlet*/ } public String tranPOST(String buffer_){/*编码翻译*/ try{ return java.net.URLDecoder.decode(buffer_, "UTF-8"); }catch(Exception e){ /*错误处理*/ return null; } } public void doGet(HttpServletRequest request,HttpServletResponse response){ try{ doPost(request,response); }catch(Exception e){ /*错误处理*/ } } public void doPost(HttpServletRequest request,HttpServletResponse response){ try{ response.setContentType("image/jpeg"); request.getSession().setAttribute("verify",writeImg(response.getOutputStream())); // System.out.println("verifycodeold:"+request.getSession().getAttribute("verifycode")); }catch(Exception e){ //错误处理 } } public String writeImg(OutputStream out){ int width = 75; int height = 20; /**应用绘图对象**/ BufferedImage bi = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB); Graphics2D gd = (Graphics2D)bi.getGraphics(); /**绘制背景**/ // gd.setColor(getRandColor(100,200)); // gd.fillRect(0, 0, width, height); // gd.setColor(java.awt.Color.WHITE); // gd.fillRect(0,0,120,70); // 红：204 绿：232 蓝：207 gd.setBackground(new Color(204,232,207)); // gd.setBackground(new Color(rnd(),rnd(),rnd())); gd.clearRect(0,0,width,height); /**设置字体**/ Font font = new Font(getRndFontNames(),Font.PLAIN,24); gd.setFont(font); /**随机字串**/ StringBuffer sb = new StringBuffer(); int i; for(i=0;i<4 ;i++ ){ sb.append(filter(rnd())); } /**设置颜色并输出**/ /** 1 所有验证码颜色一致 gd.setColor(new Color(rnd(),rnd(),rnd())); gd.drawString(sb.toString(), 0, 16); //这是普通方式，我想让所有字母颜色都不同 **/ /** 2 用随机颜色生成每个验证符**/ String st = sb.toString(); while(i>0){ /**随机颜色，并进行色彩限定**/ gd.setColor(new Color(rnd(),rnd(),rnd())); gd.drawString(st.substring(i-1,i),(i-1)*16+5,16); i--; } /**清理现场**/ gd.dispose(); bi.flush(); /**绘制**/ try{ ImageIO.write(bi,"jpg",out); }catch(IOException e){ System.o