图片验证码-java实现（转载）

2.使用java awt代码、随机数、session实现：

作者：双间 链接：www.cnblogs.com/mark5/p/109…

package com.hexianwei.graphic;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

import javax.imageio.ImageIO;

public class ImageVerificationCode {

    private int weight = 100;           //验证码图片的长和宽
    private int height = 40;
    private String text;                //用来保存验证码的文本内容
    private Random r = new Random();    //获取随机数对象
    //private String[] fontNames = {"宋体", "华文楷体", "黑体", "微软雅黑", "楷体_GB2312"};   //字体数组
    //字体数组
    private String[] fontNames = {"Georgia"};
    //验证码数组
    private String codes = "23456789abcdefghjkmnopqrstuvwxyzABCDEFGHJKMNPQRSTUVWXYZ";

    /**
     * 获取随机的颜色
     *
     * @return
     */
    private Color randomColor() {
        int r = this.r.nextInt(225);  //这里为什么是225，因为当r，g，b都为255时，即为白色，为了好辨认，需要颜色深一点。
        int g = this.r.nextInt(225);
        int b = this.r.nextInt(225);
        return new Color(r, g, b);            //返回一个随机颜色
    }

    /**
     * 获取随机字体
     *
     * @return
     */
    private Font randomFont() {
        int index = r.nextInt(fontNames.length);  //获取随机的字体
        String fontName = fontNames[index];
        int style = r.nextInt(4);         //随机获取字体的样式，0是无样式，1是加粗，2是斜体，3是加粗加斜体
        int size = r.nextInt(10) + 24;    //随机获取字体的大小
        return new Font(fontName, style, size);   //返回一个随机的字体
    }

    /**
     * 获取随机字符
     *
     * @return
     */
    private char randomChar() {
        int index = r.nextInt(codes.length());
        return codes.charAt(index);
    }

    /**
     * 画干扰线，验证码干扰线用来防止计算机解析图片
     *
     * @param image
     */
    private void drawLine(BufferedImage image) {
        int num = r.nextInt(10); //定义干扰线的数量
        Graphics2D g = (Graphics2D) image.getGraphics();
        for (int i = 0; i < num; i++) {
            int x1 = r.nextInt(weight);
            int y1 = r.nextInt(height);
            int x2 = r.nextInt(weight);
            int y2 = r.nextInt(height);
            g.setColor(randomColor());
            g.drawLine(x1, y1, x2, y2);
        }
    }

    /**
     * 创建图片的方法
     *
     * @return
     */
    private BufferedImage createImage() {
        //创建图片缓冲区
        BufferedImage image = new BufferedImage(weight, height, BufferedImage.TYPE_INT_RGB);
        //获取画笔
        Graphics2D g = (Graphics2D) image.getGraphics();
        //设置背景色随机
        g.setColor(new Color(255, 255, r.nextInt(245) + 10));
        g.fillRect(0, 0, weight, height);
        //返回一个图片
        return image;
    }

    /**
     * 获取验证码图片的方法
     *
     * @return
     */
    public BufferedImage getImage() {
        BufferedImage image = createImage();
        Graphics2D g = (Graphics2D) image.getGraphics(); //获取画笔
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < 4; i++)             //画四个字符即可
        {
            String s = randomChar() + "";      //随机生成字符，因为只有画字符串的方法，没有画字符的方法，所以需要将字符变成字符串再画
            sb.append(s);                      //添加到StringBuilder里面
            float x = i * 1.0F * weight / 4;   //定义字符的x坐标
            g.setFont(randomFont());           //设置字体，随机
            g.setColor(randomColor());         //设置颜色，随机
            g.drawString(s, x, height - 5);
        }
        this.text = sb.toString();
        drawLine(image);
        return image;
    }

    /**
     * 获取验证码文本的方法
     *
     * @return
     */
    public String getText() {
        return text;
    }

    public static void output(BufferedImage image, OutputStream out) throws IOException                  //将验证码图片写出的方法
    {
        ImageIO.write(image, "JPEG", out);
    }
}

@RequestMapping("getVerifiCode")
    @ResponseBody
    public void getVerifiCode(HttpServletRequest request, HttpServletResponse response) throws IOException {
        /*
             1.生成验证码
             2.把验证码上的文本存在session中
             3.把验证码图片发送给客户端
             */
        ImageVerificationCode ivc = new ImageVerificationCode();     //用我们的验证码类，生成验证码类对象
        BufferedImage image = ivc.getImage();  //获取验证码
        request.getSession().setAttribute("text", ivc.getText()); //将验证码的文本存在session中
        ivc.output(image, response.getOutputStream());//将验证码图片响应给客户端
    }

@RequestMapping("Login_authentication")
    @ResponseBody
    public String Login_authentication(HttpServletRequest request,HttpServletResponse response) throws IOException, ServletException {
        request.setCharacterEncoding("utf-8");
        String session_vcode=(String) request.getSession().getAttribute("text");    //从session中获取真正的验证码
        return session_vcode;
    }

<a href="javascript:getVerifiCode()">
    <img id="yzm_img" style="cursor:pointer;width: 100px;height: 36px;margin: 5px 0 0 5px;border-radius: 3px;" title="点击刷新验证码" src="Mcake/getVerifiCode"/>
</a>

function getVerifiCode() {
    $("#yzm_img").prop('src','Mcake/getVerifiCode?a='+new Date().getTime());
}