【Java】生成图形验证码

生成验证码工具类

package com.util;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Arrays;
import java.util.Random;
 
import javax.imageio.ImageIO;


public class VerifyCodeUtils {
     
    //使用到Algerian字体，系统里没有的话需要安装字体，字体只显示大写，去掉了1,0,i,o几个容易混淆的字符
    public static final String VERIFY_CODES = "23456789ABCDEFGHJKLMNPQRSTUVWXYZ";
    private static Random random = new Random();
 
 
    /**
     * 使用系统默认字符源生成验证码
     * @param verifySize    验证码长度
     * @return
     */
    public static String generateVerifyCode(int verifySize){
        return generateVerifyCode(verifySize, VERIFY_CODES);
    }
    
    /**
     * 使用指定源生成验证码
     * @param verifySize    验证码长度
     * @param sources   验证码字符源
     * @return
     */
    public static String generateVerifyCode(int verifySize, String sources){
        if(sources == null || sources.length() == 0){
            sources = VERIFY_CODES;
        }
        int codesLen = sources.length();
        Random rand = new Random(System.currentTimeMillis());
        StringBuilder verifyCode = new StringBuilder(verifySize);
        for(int i = 0; i < verifySize; i++){
            verifyCode.append(sources.charAt(rand.nextInt(codesLen-1)));
        }
        return verifyCode.toString();
    }
     
    /**
     * 生成随机验证码文件,并返回验证码值
     * @param w
     * @param h
     * @param outputFile
     * @param verifySize
     * @return
     * @throws IOException
     */
    public static String outputVerifyImage(int w, int h, File outputFile, int verifySize) throws IOException{
        String verifyCode = generateVerifyCode(verifySize);
        outputImage(w, h, outputFile, verifyCode);
        return verifyCode;
    }
     
    /**
     * 输出随机验证码图片流,并返回验证码值
     * @param w
     * @param h
     * @param os
     * @param verifySize
     * @return
     * @throws IOException
     */
    public static String outputVerifyImage(int w, int h, OutputStream os, int verifySize) throws IOException{
        String verifyCode = generateVerifyCode(verifySize);
        outputImage(w, h, os, verifyCode);
        return verifyCode;
    }
     
    /**
     * 生成指定验证码图像文件
     * @param w
     * @param h
     * @param outputFile
     * @param code
     * @throws IOException
     */
    public static void outputImage(int w, int h, File outputFile, String code) throws IOException{
        if(outputFile == null){
            return;
        }
        File dir = outputFile.getParentFile();
        if(!dir.exists()){
            dir.mkdirs();
        }
        try{
            outputFile.createNewFile();
            FileOutputStream fos = new FileOutputStream(outputFile);
            outputImage(w, h, fos, code);
            fos.close();
        } catch(IOException e){
            throw e;
        }
    }
     
    /**
     * 输出指定验证码图片流
     * @param w
     * @param h
     * @param os
     * @param code
     * @throws IOException
     */
    public static void outputImage(int w, int h, OutputStream os, String code) throws IOException{
        int verifySize = code.length();
        BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
        Random rand = new Random();
        Graphics2D g2 = image.createGraphics();
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
        Color[] colors = new Color[5];
        Color[] colorSpaces = new Color[] { Color.WHITE, Color.CYAN,
                Color.GRAY, Color.LIGHT_GRAY, Color.MAGENTA, Color.ORANGE,
                Color.PINK, Color.YELLOW };
        float[] fractions = new float[colors.length];
        for(int i = 0; i < colors.length; i++){
            colors[i] = colorSpaces[rand.nextInt(colorSpaces.length)];
            fractions[i] = rand.nextFloat();
        }
        Arrays.sort(fractions);
         
        g2.setColor(Color.GRAY);// 设置边框色
        g2.fillRect(0, 0, w, h);
         
        Color c = getRandColor(200, 250);
        g2.setColor(c);// 设置背景色
        g2.fillRect(0, 2, w, h-4);
         
        //绘制干扰线
        Random random = new Random();
        g2.setColor(getRandColor(160, 200));// 设置线条的颜色
        for (int i = 0; i < 20; i++) {
            int x = random.nextInt(w - 1);
            int y = random.nextInt(h - 1);
            int xl = random.nextInt(6) + 1;
            int yl = random.nextInt(12) + 1;
            g2.drawLine(x, y, x + xl + 40, y + yl + 20);
        }
         
        // 添加噪点
        float yawpRate = 0.05f;// 噪声率
        int area = (int) (yawpRate * w * h);
        for (int i = 0; i < area; i++) {
            int x = random.nextInt(w);
            int y = random.nextInt(h);
            int rgb = getRandomIntColor();
            image.setRGB(x, y, rgb);
        }
         
        shear(g2, w, h, c);// 使图片扭曲
 
        g2.setColor(getRandColor(100, 160));
        int fontSize = h-4;
        Font font = new Font("Algerian", Font.ITALIC, fontSize);
        g2.setFont(font);
        char[] chars = code.toCharArray();
        for(int i = 0; i < verifySize; i++){
            AffineTransform affine = new AffineTransform();
            affine.setToRotation(Math.PI / 4 * rand.nextDouble() * (rand.nextBoolean() ? 1 : -1), (w / verifySize) * i + fontSize/2, h/2);
            g2.setTransform(affine);
            g2.drawChars(chars, i, 1, ((w-10) / verifySize) * i + 5, h/2 + fontSize/2 - 10);
        }
         
        g2.dispose();
        ImageIO.write(image, "png", os);
    }
     
    private static Color getRandColor(int fc, int bc) {
        if (fc > 255)
            fc = 255;
        if (bc > 255)
            bc = 255;
        int r = fc + random.nextInt(bc - fc);
        int g = fc + random.nextInt(bc - fc);
        int b = fc + random.nextInt(bc - fc);
        return new Color(r, g, b);
    }
     
    private static int getRandomIntColor() {
        int[] rgb = getRandomRgb();
        int color = 0;
        for (int c : rgb) {
            color = color << 8;
            color = color | c;
        }
        return color;
    }
     
    private static int[] getRandomRgb() {
        int[] rgb = new int[3];
        for (int i = 0; i < 3; i++) {
            rgb[i] = random.nextInt(255);
        }
        return rgb;
    }
 
    private static void shear(Graphics g, int w1, int h1, Color color) {
        shearX(g, w1, h1, color);
        shearY(g, w1, h1, color);
    }
     
    private static void shearX(Graphics g, int w1, int h1, Color color) {
 
        int period = random.nextInt(2);
 
        boolean borderGap = true;
        int frames = 1;
        int phase = random.nextInt(2);
 
        for (int i = 0; i < h1; i++) {
            double d = (double) (period >> 1)
                    * Math.sin((double) i / (double) period
                            + (6.2831853071795862D * (double) phase)
                            / (double) frames);
            g.copyArea(0, i, w1, 1, (int) d, 0);
            if (borderGap) {
                g.setColor(color);
                g.drawLine((int) d, i, 0, i);
                g.drawLine((int) d + w1, i, w1, i);
            }
        }
 
    }
 
    private static void shearY(Graphics g, int w1, int h1, Color color) {
 
        int period = random.nextInt(40) + 10; // 50;
 
        boolean borderGap = true;
        int frames = 20;
        int phase = 7;
        for (int i = 0; i < w1; i++) {
            double d = (double) (period >> 1)
                    * Math.sin((double) i / (double) period
                            + (6.2831853071795862D * (double) phase)
                            / (double) frames);
            g.copyArea(i, 0, 1, h1, 0, (int) d);
            if (borderGap) {
                g.setColor(color);
                g.drawLine(i, (int) d, i, 0);
                g.drawLine(i, (int) d + h1, i, h1);
            }
 
        }
    }
    public static void main(String[] args) throws IOException{
        File dir = new File("C:/Users/H__D/Desktop/");
        int w = 200, h = 80;
        String verifyCode = generateVerifyCode(4);
        File file = new File(dir, verifyCode + ".jpg");
        outputImage(w, h, file, verifyCode);
    }
}

使用图形验证码

　　1、使用流程

　　　　

　　2、服务器端生成验证码servlet

package com.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.util.VerifyCodeUtils;


public class CreateCodeServlet extends HttpServlet {
    
    
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setHeader("Pragma", "No-cache");  
        resp.setHeader("Cache-Control", "no-cache");  
        resp.setDateHeader("Expires", 0);  
        resp.setContentType("image/jpeg");  
          
        //生成随机字串  
        String verifyCode = VerifyCodeUtils.generateVerifyCode(4);  
        //存入会话session  
        req.getSession().setAttribute("CODE", verifyCode.toLowerCase());  
        
        //生成图片  
        int width = 100;//宽
        int height = 40;//高  
        VerifyCodeUtils.outputImage(width, height, resp.getOutputStream(), verifyCode);  
        
    }
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doGet(req, resp);
    }
}

3、服务器端验证验证码servlet

package com.servlet;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.util.VerifyCodeUtils;


public class VerifyCodeServlet extends HttpServlet {
    
    
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
        String code = req.getParameter("code");
        String key = (String) req.getSession().getAttribute("CODE");
        if(code != null && code.equalsIgnoreCase(key)){
            req.getSession().removeAttribute("CODE");
            resp.getWriter().println(true);
        }else{
            resp.getWriter().println(false);
        }
    }
    
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // TODO Auto-generated method stub
        super.doGet(req, resp);
    }
}

4、servet的注册，web.xml文件

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>test-captcha</display-name>
  
  
  <servlet>
      <servlet-name>CreateCodeServlet</servlet-name>
      <servlet-class>com.servlet.CreateCodeServlet</servlet-class>
  </servlet>
  <servlet-mapping>
      <servlet-name>CreateCodeServlet</servlet-name>
      <url-pattern>/createCode</url-pattern>
  </servlet-mapping>
  
   <servlet>
      <servlet-name>VerifyCodeServlet</servlet-name>
      <servlet-class>com.servlet.VerifyCodeServlet</servlet-class>
  </servlet>
  <servlet-mapping>
      <servlet-name>VerifyCodeServlet</servlet-name>
      <url-pattern>/verifyCode</url-pattern>
  </servlet-mapping>

  
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

5、前端html文件

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
    <h2>测试验证码：</h2>
    请输入验证码：<input type="text" name="code" /><img id="codeimg" src="${pageContext.request.contextPath }/createCode" onclick="changeImg()"><a href="javascript:void(0);" onclick="changeImg()">看不清，换一张</a>
    <button onclick="submit()">提交</button>
    <script type="text/javascript">
    
        //改变验证码事件
        function changeImg(){
            var img = document.getElementById('codeimg');
            img.src = "${pageContext.request.contextPath }/createCode?x=" + Math.floor(Math.random()*100)
        }
        
        //提交验证并验证验证码
        function submit(){
            var input = document.getElementsByTagName('input')[0];
            
            //ajax提交
            var xhr = new XMLHttpRequest();
            
            xhr.onreadystatechange = function(){
                if(xhr.readyState == 4 && xhr.status == 200) {
                    alert(xhr.responseText);
                }  
            }
            
            xhr.open('get','${pageContext.request.contextPath }/verifyCode?code=' + input.value);
            xhr.send(null);
            
        }
        
        
        
    </script>
</body>
</html>

6、使用浏览器打开页面访问，效果图如下：
　　　　

 此文来源于： https://www.cnblogs.com/h--d/p/8258610.html