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 }