spring mvc 实现的验证码功能

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;


@Controller
@RequestMapping("/checkCodeAction/")
public class CheckCode extends HttpServlet {

 public CheckCode() {
  super();
 }

 public void destroy() {
  super.destroy(); 
 }

 public void init() throws ServletException {
  super.init();
 }

 public Color getRandColor(int s, int e) {
  Random random = new Random();
  if (s > 255) s = 255;
  if (e > 255) e = 255;
  int r = s + random.nextInt(e - s);
  int g = s + random.nextInt(e - s);
  int b = s + random.nextInt(e - s);
  return new Color(r, g, b);
 }
 
 @RequestMapping("service.do")
 public void service(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  //禁止缓存
  response.setHeader("Pragma", "No-cache");
  response.setHeader("Cache-Control", "No-cache");
  response.setDateHeader("Expires", 0);
  // 指定生成的响应是图片
  response.setContentType("image/jpeg");
  int width = 200;
  int height = 60;
  BufferedImage image = new BufferedImage(width, height,
    BufferedImage.TYPE_INT_RGB);    //创建BufferedImage类的对象
  Graphics g = image.getGraphics();     //创建Graphics类的对象
  Graphics2D g2d=(Graphics2D)g;      //通过Graphics类的对象创建一个Graphics2D类的对象
  Random random = new Random();      //实例化一个Random对象
  Font mFont = new Font("华文宋体", Font.BOLD, 30);  //通过Font构造字体
  g.setColor(getRandColor(200, 250));     //改变图形的当前颜色为随机生成的颜色
  g.fillRect(0, 0, width , height);     //绘制一个填色矩形

  //画一条折线  
  BasicStroke bs=new BasicStroke(2f,BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL); //创建一个供画笔选择线条粗细的对象
  g2d.setStroke(bs);     //改变线条的粗细
  g.setColor(Color.DARK_GRAY);  //设置当前颜色为预定义颜色中的深灰色
  int[] xPoints=new int[3];
  int[] yPoints=new int[3];
  for(int j=0;j<3;j++){
   xPoints[j]=random.nextInt(width - 1);
   yPoints[j]=random.nextInt(height - 1);
  }
  g.drawPolyline(xPoints, yPoints,3);
  //生成并输出随机的验证文字  
  g.setFont(mFont);  
  String sRand="";
  int itmp=0;
  for(int i=0;i<4;i++){
   if(random.nextInt(2)==1){
    itmp=random.nextInt(26)+65; //生成A~Z的字母
   }else{
    itmp=random.nextInt(10)+48; //生成0~9的数字
   }
   char ctmp=(char)itmp;
   sRand+=String.valueOf(ctmp);
   Color color=new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110));
   g.setColor(color);
   /****随机缩放文字并将文字旋转指定角度**/
   //将文字旋转指定角度
   Graphics2D g2d_word=(Graphics2D)g;
   AffineTransform trans=new AffineTransform();
   trans.rotate(random.nextInt(45)*3.14/180,15*i+10,7);
   //缩放文字
   float scaleSize=random.nextFloat()+0.8f;
   if(scaleSize>1.1f) scaleSize=1f;
   trans.scale(scaleSize, scaleSize);
   g2d_word.setTransform(trans);
   /************************/
   g.drawString(String.valueOf(ctmp),30*i+40,16);

  }
  //将生成的验证码保存到Session中
  HttpSession session=request.getSession(true);
  session.setAttribute("randCheckCode",sRand);
  g.dispose();
  ImageIO.write(image,"JPEG",response.getOutputStream());
 }

} 

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