java实现简单验证码生成

本文实例为大家分享了java验证码生成的具体代码，供大家参考，具体内容如下

简单验证码java实现--servlet类生成 验证码img，并写入session

老师给的源码，在此做个记录，简单验证码，java绘图

在此鸣谢并附上源码：.

//
package app61;

import java.io.*;
import java.util.*;
import com.sun.image.codec.jpeg.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.awt.*;
import java.awt.image.*;

public class VerifyCode extends HttpServlet {

private Font mFont = new Font("Times New Roman", Font.PLAIN, 18); //设置字体

public void doGet(HttpServletRequest request, HttpServletResponse response) throws
ServletException, IOException {
//取得一个1000-9999的随机数
HttpSession session = request.getSession(true);
response.setContentType("image/gif");
response.setHeader("Pragma", "No-cache");
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
int width = 60, height = 20;

ServletOutputStream out = response.getOutputStream();
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB); //设置图片大小的
Graphics gra = image.getGraphics();
Random random = new Random();
gra.setColor(getRandColor(200, 250)); //设置背景色rand垫底
gra.fillRect(0, 0, width, height);
gra.setColor(Color.black); //设置字体色
gra.setFont(mFont);
// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
gra.setColor(getRandColor(160, 200));
for (int i = 0; i < 155; i++) {
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(12);
int yl = random.nextInt(12);
gra.drawLine(x, y, x + xl, y + yl);
}

// 取随机产生的认证码(4位数字)
String sRand = "";
for (int i = 0; i < 4; i++) {
String rand = String.valueOf(random.nextInt(10));
sRand += rand;
// 将认证码显示到图象中
gra.setColor(new Color(20 + random.nextInt(110),
20 + random.nextInt(110),
20 + random.nextInt(110))); //调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
gra.drawString(rand, 13 * i + 6, 16);
}
session.setAttribute("rand",sRand);
// session.setAttribute("getImg", sRand);
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
encoder.encode(image);
out.close();
}

static Color getRandColor(int fc, int bc) { //给定范围获得随机颜色
Random random = new Random();
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);
}

//Clean up resources
public void destroy() {
}
}

来源：https://blog.csdn.net/weixin_42692989/article/details/89556291#java_7