java语言实现登录验证码功能

雨点打透心脏的1/2处 2022-05-10 14:04 242阅读 0赞

# **先上效果。** #

![70][]

# 生成验证码后端逻辑 #

import java.awt.Color;
    import java.awt.Font;
    import java.awt.Graphics2D;
    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.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    
    @Controller
    @RequestMapping("/verificationCode")
    public class VerifyCodeController {
    	private static final long serialVersionUID = 1L;
    	 /**
         * 这里用作存入session的名称
         */
        private static final String SESSION_KEY_OF_RAND_CODE = "randCode"; 
    
        /**
         * 
         */
        private static final int count = 200;
    
        /**
         * 定义图形大小(宽)
         */
        private static final int width = 105;
        /**
         * 定义图形大小(高)
         */
        private static final int height = 35;
        /**
         * 干扰线的长度=1.414*lineWidth
         */
        private static final int lineWidth = 1;
    
        @RequestMapping(value= "/generate", method={ RequestMethod.POST,RequestMethod.GET })
        public void VerificationCode( HttpServletRequest request,
                HttpServletResponse response) throws ServletException,
                IOException {
                // 设置页面不缓存
                    response.setHeader("Pragma", "No-cache");
                    response.setHeader("Cache-Control", "no-cache");
                    response.setDateHeader("Expires", 0);
                    // response.setContentType("image/png");
                    // 在内存中创建图象
                    final BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
                    // 获取图形上下文
                    final Graphics2D graphics = (Graphics2D) image.getGraphics();
    
                    // 设定背景颜色
                    graphics.setColor(Color.WHITE); // ---1.Color.WHITE为白色
                    graphics.fillRect(0, 0, width, height);//填充衍射
                    // 设定边框颜色
                    //graphics.setColor(getRandColor(100, 200)); // ---2.这是以数字型来设置颜色，颜色模式是指使用三种基色：红、绿、蓝，通过三种颜色的调整得出其它各种颜色，这三种基色的值范围为0～255
                    graphics.drawRect(0, 0, width - 1, height - 1);
    
    
                    final Random random = new Random();
                    // 随机产生干扰线，使图象中的认证码不易被其它程序探测到
                    for (int i = 0; i < count; i++) {
                        graphics.setColor(getRandColor(150, 200)); // ---3.
    
                        final int x = random.nextInt(width - lineWidth - 1) + 1; // 保证画在边框之内
                        final int y = random.nextInt(height - lineWidth - 1) + 1;
                        final int xl = random.nextInt(lineWidth);
                        final int yl = random.nextInt(lineWidth);
                        graphics.drawLine(x, y, x + xl, y + yl);
                    }
                    // 取随机产生的认证码(4位数字)
                    final String resultCode = exctractRandCode();
                    for (int i = 0; i < resultCode.length(); i++) {
                    	int num=(int)(Math.random()*4+1);
                    	switch (num) {
    					case 1:
    						graphics.setColor(Color.green);
    						break;
    					case 2:
    						graphics.setColor(Color.black);
    						break;
    					case 3:
    						graphics.setColor(Color.blue);
    						break;
    					case 4:
    						graphics.setColor(Color.red);
    						break;
    					default:
    						graphics.setColor(Color.green);
    						break;
    					}
                       
                       
                        graphics.setFont(new Font("Times New Roman", Font.BOLD, 24));
                        // 设置字符，字符间距，上边距
                        //System.out.print(resultCode.charAt(i));
                        graphics.drawString(String.valueOf(resultCode.charAt(i)), (23 * i) + 8, 26);
                    }
                   // System.out.println("直接输出："+resultCode);
                    // 将认证码存入SESSION
                    request.getSession().setAttribute(SESSION_KEY_OF_RAND_CODE, resultCode);
                    // 图象生效
                    graphics.dispose();
    
                    // 输出图象到页面
                    ImageIO.write(image, "JPEG", response.getOutputStream());           
        }
    
    
        /**
         * @return 随机码
         */
        private String exctractRandCode() {
            
            int randCodeLength = 4;
            
            return RandCodeImageEnum.ALL_CHAR.generateStr(randCodeLength);
    
        }
    
    
    
    
        /**
         * 描述：根据给定的数字生成不同的颜色
         * @param 这是以数字型来设置颜色，颜色模式是指使用三种基色：红、绿、蓝，通过三种颜色的调整得出其它各种颜色，这三种基色的值范围为0～255
         * @param 这是以数字型来设置颜色，颜色模式是指使用三种基色：红、绿、蓝，通过三种颜色的调整得出其它各种颜色，这三种基色的值范围为0～255
         * @return 描述：返回颜色
         */
        private Color getRandColor(int fc, int bc) { // 取得给定范围随机颜色
            final Random random = new Random();
            if (fc > 255) {
                fc = 255;
            }
            if (bc > 255) {
                bc = 255;
            }
    
            final int r = fc + random.nextInt(bc - fc);
            final int g = fc + random.nextInt(bc - fc);
            final int b = fc + random.nextInt(bc - fc);
    
            return new Color(r, g, b);
        }
    
    
    
        /**
         * 验证码辅助类
         */
        enum RandCodeImageEnum {
            /**
             * 混合字符串
             */
            ALL_CHAR("0123456789abcdefghijkmnpqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"), // 去除小写的l和o这个两个不容易区分的字符；
            /**
             * 字符
             */
            LETTER_CHAR("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"),
            /**
             * 小写字母
             */
            LOWER_CHAR("abcdefghijklmnopqrstuvwxyz"),
            /**
             * 数字
             */
            NUMBER_CHAR("0123456789"),
            /**
             * 大写字符
             */
            UPPER_CHAR("ABCDEFGHIJKLMNOPQRSTUVWXYZ");
            /**
             * 待生成的字符串
             */
            private String charStr;
    
            /**
             * @param charStr
             */
            private RandCodeImageEnum(final String charStr) {
                this.charStr = charStr;
            }
    
            /**
             * 生产随机验证码
             * 
             * @param codeLength
             *            验证码的长度
             * @return 验证码
             */
            public String generateStr(final int codeLength) {
                final StringBuffer sb = new StringBuffer();
                final Random random = new Random();
                final String sourseStr = getCharStr();
    
                for (int i = 0; i < codeLength; i++) {
                    sb.append(sourseStr.charAt(random.nextInt(sourseStr.length())));
                }
    
                return sb.toString();
            }
    
            /**
             * @return the {@link #charStr}
             */
            public String getCharStr() {
                return charStr;
            }
    
        }
    }

# 前端代码： #

# 登录操作controller层代码。登录前先判断验证码是否输入错误。 #

HttpSession session = request.getSession();
    		String sessionCode=session.getAttribute("randCode")==null?"":session.getAttribute("randCode").toString();
    		
    	    if(!sessionCode.equalsIgnoreCase(code)){//验证码错误
    			return 0;
    		}

end~

[70]: /images/20220505/5f07df56fed746939e1dd31ab37075ad.png