Use java to implement login verification code (full code)

1. First write a verification code tool class

package com.yx.cus.util;import java.awt.BasicStroke;import java.awt.Color;import java.awt.Font;import java.awt.Graphics2D;import java.awt.image.BufferedImage;import java.io.IOException;import java.io.OutputStream;import java.util.Random;import javax.imageio.ImageIO;public class VerifyCode {
    private int w = 70;    private int h = 35;    private Random r = new Random();    // {"宋体", "华文楷体", "黑体", "华文新魏", "华文隶书", "微软雅黑", "楷体_GB2312"}
    private String[] fontNames  = {"宋体", "华文楷体", "黑体", "微软雅黑", "楷体_GB2312"};    private String codes  = "23456789abcdefghjkmnopqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ";    private Color bgColor  = new Color(255, 255, 255);    public static String text ;    private Color randomColor () {        int red = r.nextInt(150);        int green = r.nextInt(150);        int blue = r.nextInt(150);        return new Color(red, green, blue);
    }    private Font randomFont () {        int index = r.nextInt(fontNames.length);
        String fontName = fontNames[index];        int style = r.nextInt(4);        int size = r.nextInt(5) + 24; 
        return new Font(fontName, style, size);//指定字体名称、样式和点大小，创建一个新 Font。
    }    //画干扰的线条
    private void drawLine (BufferedImage image) {        int num  = 3;//画三条
        Graphics2D g2 = (Graphics2D)image.getGraphics();        for(int i = 0; i < num; i++) {            int x1 = r.nextInt(w);            int y1 = r.nextInt(h);            int x2 = r.nextInt(w);            int y2 = r.nextInt(h); 
            g2.setStroke(new BasicStroke(1.5F)); 
            g2.setColor(Color.BLUE); 
            g2.drawLine(x1, y1, x2, y2);
        }
    }    private char randomChar () {        int index = r.nextInt(codes.length());        return codes.charAt(index);
    }    private BufferedImage createImage () {
        BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB); 
        Graphics2D g2 = (Graphics2D)image.getGraphics(); 
        g2.setColor(this.bgColor);
        g2.fillRect(0, 0, w, h);        return image;
    }    public BufferedImage getImage () {
        BufferedImage image = createImage(); 
        Graphics2D g2 = (Graphics2D)image.getGraphics();
        StringBuilder sb = new StringBuilder();        // 向图片中画4个字符
        for(int i = 0; i < 4; i++)  {
            String s = randomChar() + ""; 
            sb.append(s); 
            float x = i * 1.0F * w / 4; 
            g2.setFont(randomFont()); 
            g2.setColor(randomColor()); 
            /**
             * 首字符的基线位于用户空间的 (x, h-5) 位置处
             * 原点在左上角,X轴递增的方向是从左向右;Y轴是从上到下
             * 在提供的坐标位于基线上最左边字符的情况下，可以从右到左呈现字形
             * h-5表示y轴方向,向上偏移了5
             */
            g2.drawString(s, x, h-5); 
        }        this.text = sb.toString(); 
        drawLine(image); 
        return image;       
    }    public String getText () {        return text;
    }    public static void output (BufferedImage image, OutputStream out) 
                throws IOException {
        ImageIO.write(image, "JPEG", out);
    }
}

We mainly use two methods for this tool class:
1. Use the getImage() method to make the verification code and return the BufferedImage type Verification code
2. Get the text of the verification code through the getText() method and return the String type
2. Verification code interface (controller)

/**
 * 验证码
 * @param request
 * @return
 * @throws Exception 
 */@RequestMapping(value = "/VC", method = RequestMethod.POST)@ResponseBodypublic void  VC(HttpServletRequest request, HttpServletResponse response ) throws Exception{ 
   VerifyCode code=new VerifyCode();
   BufferedImage image = code.getImage();   //将验证码文本存到Redis
   vckey=IDUtil.nextId();
   JedisClient.set(vckey, code.getText(),60);
   ImageIO.write(image,"jpg",response.getOutputStream()); 
}

This interface will return a verification code to the front end in the form of a stream. Before returning, a unique identifier will be generated and assigned to a global variable for use in redis. Store the text of the verification code in it for later use. The stored text has a time limit.
3. The interface for obtaining the text identification of the verification code (that is, the value of the verification code text stored)

/**
 * 验证码文本的标识
 * @param request
 * @return
 * @throws Exception 
 */
   @RequestMapping(value = "/VCkey", method = RequestMethod.POST)@ResponseBodypublic String  VCkey(HttpServletRequest request, HttpServletResponse response ) throws Exception{ 
       System.out.println(vckey);   return vckey;
}

This interface mainly returns the key that stores the verification code text in redis to the front end, and then returns the login interface together when logging in
4. Login interface (example)

String user_phone = reqstr.get("user_phone");//账号String user_pwd   = reqstr.get("user_pwd");//密码String vc   = reqstr.get("vc").toLowerCase();//用户输入的验证码String vckey   = reqstr.get("vckey");//前端获取的验证码文本的键（标识）String vcode= (String)JedisClient.get(vckey);//通过标识从redis里获取验证码文本if(vc.equals(vcode.toLowerCase())) {//用户输入的验证码与redsi存的作比较
   “验证码成功”
}else if（vcode==null）{
    “验证码以过期”
}else{
     “验证码错误”
}

Supplement: Verification The key (identification) of the code can also be generated on the front end, such as generating a timestamp and passing it in as a parameter when requesting the verification code interface, so that the backend can write one less interface and global variable

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