JAVA代码制作验证码，可用于注册等功能页面
要导入servlet-api.jar包
创建验证码的Util工具类：
先创建图片并生成随机的验证码字母
设置图片的底色，并用setFont函数将验证码画在图片上，如果想让验证码难一点，可以添加for循环的代码给图片增加旋转角度
给验证码增加干扰线，提高安全性
设置边框
创建VerifyPic的servlet，通过Util类获取代码，并存入session中，然后输送去前端页面
前端页面验证码如下：
完整Util工具类代码如下：
package com.sport.util;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.util.HashMap;
import java.util.Map;
public class VerifyUtil {
public static Map<String, Object> generateVerify(){
//创建一张图片
BufferedImage verifyPic = new BufferedImage(120,40,BufferedImage.TYPE_3BYTE_BGR);
//通过图片获取画笔
Graphics2D g = verifyPic.createGraphics();
//准备一个字母+数字的字典
String letters = "23456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
//规定验证码的位数
int verifyLength = 4;
//生成随机验证码
String verifyCode = "";
//循环取值
for(int i=0; i<verifyLength; i++) {
verifyCode +=letters.charAt((int)(Math.random()*letters.length()));
}
//将图片的底板由黑变白
g.setColor(Color.white);
g.fillRect(0, 0, 120, 40);
//将验证码画在图片之上
g.setFont(new Font("微软雅黑",Font.BOLD, 24));
for (int i = 0; i < verifyLength; i++) {
//随机产生一个角度
double theta = Math.random() * Math.PI / 4 * ((int)(Math.random()*2) == 0?1:-1);
//产生偏转
g.rotate(theta, 24+i*22, 20);
//每画一个字幕之前都随机给一个颜色
g.setColor(new Color((int)(Math.random()*256), (int)(Math.random()*256), (int)(Math.random()*256)));
g.drawString(verifyCode.charAt(i)+"", 20+i*22 , 26);
//回正
g.rotate(-theta, 24+i*22, 20);
}
//加入干扰线
for (int i = 0; i < 5; i++) {
//给随机颜色
g.setColor(new Color((int)(Math.random()*256), (int)(Math.random()*256), (int)(Math.random()*256)));
//画线
g.drawLine((int)(Math.random()*120), (int)(Math.random()*40),
(int)(Math.random()*120), (int)(Math.random()*40));
}
//设置边框颜色
g.setColor(Color.black);
//给验证码一个外边框
g.drawRect(0, 0, 118, 38);
//将验证码和图片一起存入map
Map<String, Object> data = new HashMap<String, Object>();
data.put("verifyCode", verifyCode);
data.put("verifyPic", verifyPic);
return data;
}
}
完整VerifyPic的代码如下：
package com.sport.servlet;
import com.sport.util.VerifyUtil;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Map;
@WebServlet("/VerifyPic")
public class VerifyPic extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
Map<String, Object> data = VerifyUtil.generateVerify();
//获取验证码
String verifyCode = (String) data.get("verifyCode");
//将验证码存入session
HttpSession session = request.getSession();
session.setAttribute("verifyCode", verifyCode);
//获取图片
BufferedImage verifyPic = (BufferedImage) data.get("verifyPic");
//输出图片给前端，使用工具类ImageIO
ImageIO.write(verifyPic, "jpg", response.getOutputStream());
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
总结
