输出随机认证码图片

  1 package cn.itcast.response;
  2 
  3 import java.awt.Color;
  4 import java.awt.Font;
  5 import java.awt.Graphics;
  6 import java.awt.Graphics2D;
  7 import java.awt.image.BufferedImage;
  8 import java.io.FileInputStream;
  9 import java.io.IOException;
 10 import java.io.InputStream;
 11 import java.io.OutputStream;
 12 import java.io.PrintWriter;
 13 import java.util.Random;
 14 
 15 import javax.imageio.ImageIO;
 16 import javax.servlet.ServletException;
 17 import javax.servlet.http.HttpServlet;
 18 import javax.servlet.http.HttpServletRequest;
 19 import javax.servlet.http.HttpServletResponse;
 20 
 21 public class ResponseDemo extends HttpServlet {
 22 
 23     public static final int WIDTH = 120;
 24     public static final int HEIGHT = 45;
 25 
 26     public void doGet(HttpServletRequest request, HttpServletResponse response)
 27             throws ServletException, IOException {
 28 
 29         BufferedImage image = new BufferedImage(WIDTH, HEIGHT,
 30                 BufferedImage.TYPE_INT_RGB);
 31 
 32         Graphics g = image.getGraphics();
 33 
 34         // 1.设置背景色
 35         setBackGround(g);
 36 
 37         // 2.设置边框
 38         setBorder(g);
 39 
 40         // 3.画干扰线
 41         drawRandomLine(g);
 42 
 43         // 4.写随机数
 44         drawRandomNum((Graphics2D) g);
 45 
 46         // 5.图形写给浏览器
 47         response.setContentType("image/jpeg");
 48         
 49         //发头控制浏览器不要缓存
 50         response.setDateHeader("expries", -1);
 51         response.setHeader("Cache-Control", "no-cache");
 52         response.setHeader("Pragma", "no-cache");
 53         ImageIO.write(image, "jpg", response.getOutputStream());
 54     }
 55 
 56     private void drawRandomNum(Graphics2D g) {
 57 
 58         g.setColor(Color.RED);
 59         g.setFont(new Font("宋体",Font.BOLD,20));
 60         
 61         String base = "\u7684\u4e00\u662f\u6211\u4e0d\u5728\u4eba";
 62         
 63         int x=5;
 64         for(int i=0;i<4;i++){
 65             
 66             int degree = new Random().nextInt()%30;
 67             
 68             String ch = base.charAt(new Random().nextInt(base.length()))+"";
 69             
 70             g.rotate(degree*Math.PI/180,x,20);//设置旋转角度
 71             g.drawString(ch, x, 20);
 72             g.rotate(-degree*Math.PI/180,x,20);
 73             x+=30;
 74         }
 75 
 76     }
 77 
 78     private void drawRandomLine(Graphics g) {
 79         g.setColor(Color.GREEN);
 80         for (int i = 0; i < 5; i++) {
 81             int x1 = new Random().nextInt(WIDTH);
 82             int y1 = new Random().nextInt(HEIGHT);
 83 
 84             int x2 = new Random().nextInt(WIDTH);
 85             int y2 = new Random().nextInt(HEIGHT);
 86 
 87             g.drawLine(x1, y1, x2, y2);
 88         }
 89     }
 90 
 91     private void setBorder(Graphics g) {
 92 
 93         g.setColor(Color.BLUE);
 94         g.drawRect(1, 1, WIDTH - 2, HEIGHT - 2);
 95 
 96     }
 97 
 98     private void setBackGround(Graphics g) {
 99 
100         g.setColor(Color.WHITE);
101         g.fillRect(0, 0, WIDTH, HEIGHT);
102 
103     }
104 
105     public void doPost(HttpServletRequest request, HttpServletResponse response)
106             throws ServletException, IOException {
107 
108     }
109 
110 }