登录验证码java后台实现流程

作者：阳旭006

依赖技术：redis的简单使用

一、先写一个验证码工具类

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);
    }
}

这个工具类我们主要使用两个方法：
1.通过getImage()方法来制作验证码，返回BufferedImage 类型的验证码
2.通过getText()方法获取验证码的文本，返回String类型
二。验证码的接口（controller）

/**
 * 验证码
 * @param request
 * @return
 * @throws Exception 
 */
@RequestMapping(value = "/VC", method = RequestMethod.POST)
@ResponseBody
public 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()); 
} 

该接口会返回前端一个验证码，是以流的形式返回的，在返回之前会生成一个唯一的标识赋给一个全局变量，用来在redis里存入该验证码的文本，以作后用，存入的文本有时间限制
三、获取验证码文本标识的接口（就是存入验证码文本的值）

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

该接口主要就是把在redis里存验证码文本的键返回给前端，然后在登录的时候一起传回登录的接口
四、登录接口（试例）

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”
}

补充：验证码的键（标识）也可以在前端生成,比如生成一个时间戳，在请求验证码的接口时作为参数传入，这样后台就可以少写一个接口和全局变量