Java 生成验证码图片

2019-03-06 07:16:17来源：博客园阅读 ()

  1 import java.awt.image.BufferedImage;
  2 import java.io.BufferedReader;
  3 
  4 import java.awt.Color;
  5 import java.io.FileReader;
  6 import java.io.IOException;
  7 import java.util.ArrayList;
  8 import java.util.List;
  9 import java.util.Random;
 10 
 11 import java.awt.Font;
 12 import java.awt.Graphics;
 13 import java.awt.Graphics2D;
 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 /**
 22  * 验证码生成程序
 23  */
 24 public class CheckChengyu extends HttpServlet {
 25 
 26 // 集合中保存所有成语
 27     private List<String> words = new ArrayList<String>();
 28 
 29     @Override
 30     public void init() throws ServletException {
 31 // 初始化阶段，读取qy95.txt
 32 // web工程中读取 文件，必须使用绝对磁盘路径
 33         String path = getServletContext().getRealPath("/WEB-INF/chengyu.txt");
 34         try {
 35             BufferedReader reader = new BufferedReader(new FileReader(path));
 36             String line;
 37             while ((line = reader.readLine()) != null) {
 38                 words.add(line);
 39             }
 40             reader.close();
 41         } catch (IOException e) {
 42             e.printStackTrace();
 43         }
 44     }
 45 
 46     public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
 47 // 禁止缓存
 48 // response.setHeader("Cache-Control", "no-cache");
 49 // response.setHeader("Pragma", "no-cache");
 50 // response.setDateHeader("Expires", -1);
 51 
 52         int width = 120;
 53         int height = 30;
 54 
 55 // 步骤一 绘制一张内存中图片
 56         BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
 57 
 58 // 步骤二 图片绘制背景颜色 ---通过绘图对象
 59         Graphics graphics = bufferedImage.getGraphics();// 得到画图对象 --- 画笔
 60 // 绘制任何图形之前 都必须指定一个颜色
 61         graphics.setColor(getRandColor(200, 250));
 62         graphics.fillRect(0, 0, width, height);
 63 
 64 // 步骤三 绘制边框
 65         graphics.setColor(Color.WHITE);
 66         graphics.drawRect(0, 0, width - 1, height - 1);
 67 
 68 // 步骤四 四个随机数字
 69         Graphics2D graphics2d = (Graphics2D) graphics;
 70 // 设置输出字体
 71         graphics2d.setFont(new Font("宋体", Font.BOLD, 18));
 72 
 73         Random random = new Random();// 生成随机数
 74         int index = random.nextInt(words.size());
 75         String word = words.get(index);// 获得成语
 76 
 77 // 定义x坐标
 78         int x = 10;
 79         for (int i = 0; i < word.length(); i++) {
 80 // 随机颜色
 81         graphics2d.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));
 82
 83 // 旋转 -30 --- 30度
 84             int jiaodu = random.nextInt(60) - 30;
 85 // 换算弧度
 86             double theta = jiaodu * Math.PI / 180;
 87 
 88 // 获得字母数字
 89             char c = word.charAt(i);
 90 
 91 // 将c 输出到图片
 92             graphics2d.rotate(theta, x, 20);
 93             graphics2d.drawString(String.valueOf(c), x, 20);
 94             graphics2d.rotate(-theta, x, 20);
 95             x += 30;
 96         }
 97 
 98 // 将验证码内容保存session
 99         request.getSession().setAttribute("checkcode_session", word);
100 
101 // 步骤五 绘制干扰线
102         graphics.setColor(getRandColor(160, 200));
103         int x1;
104         int x2;
105         int y1;
106         int y2;
107         for (int i = 0; i < 30; i++) {
108             x1 = random.nextInt(width);
109             x2 = random.nextInt(12);
110             y1 = random.nextInt(height);
111             y2 = random.nextInt(12);
112             graphics.drawLine(x1, y1, x1 + x2, x2 + y2);
113         }
114 
115 // 将上面图片输出到浏览器 ImageIO
116         graphics.dispose();// 释放资源
117 
118 //将图片写到response.getOutputStream()中
119         ImageIO.write(bufferedImage, "jpg", response.getOutputStream());
120 
121     }
122 
123     public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
124         doGet(request, response);
125     }
126 
127     /**
128      * 取其某一范围的color
129      * 
130      * @param fc int 范围参数1
131      * @param bc int 范围参数2
132      * @return Color
133      */
134     private Color getRandColor(int fc, int bc) {
135 // 取其随机颜色
136         Random random = new Random();
137         if (fc > 255) {
138             fc = 255;
139         }
140         if (bc > 255) {
141             bc = 255;
142         }
143         int r = fc + random.nextInt(bc - fc);
144         int g = fc + random.nextInt(bc - fc);
145         int b = fc + random.nextInt(bc - fc);
146         return new Color(r, g, b);
147     }
148 
149 }