随机验证码

import java.awt.image.BufferedImage;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.io.IOException;
import java.util.Random;

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

public class ResponseDemo4 extends HttpServlet {

    public static final int WIDTH = 120;
    public static final int HEIGHT = 35;

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        BufferedImage image = new BufferedImage(WIDTH, HEIGHT,
                BufferedImage.TYPE_INT_RGB);
        Graphics g = image.getGraphics();
        // 设置背景色
        setBackGround(g);
        // 设置边框
        setBored(g);
        // 画干扰线
        drawRandomLine(g);
        // 写随机数字
        drawRandowNum((Graphics2D) g);
        // 图形写给浏览器
        response.setContentType("image/jpeg");
        // 控制浏览器不要拿缓存
        response.setDateHeader("expries", -1);
        response.setHeader("Cache-Control", "no-cache");
        response.setHeader("Pragma", "no-cache");

        ImageIO.write(image, "jpg", response.getOutputStream());

    }

    public void drawRandowNum(Graphics2D g) {
        g.setColor(Color.RED);
        g.setFont(new Font("黑体", Font.BOLD, 20));
        String base = "u7684u4e00u662fu4e86u6211u4e0du4ebau5728u4ed6u6709u8fd9u4e2au4e0au4eecu6765 u5230u65f6u5927u5730u4e3au5b50u4e2du4f60u8bf4u751fu56fdu5e74u7740u5c31u90a3 u548cu8981u5979u51fau4e5fu5f97u91ccu540eu81eau4ee5u4f1au5bb6u53efu4e0bu800cu8fc7u5929u53bbu80fdu5bf9u5c0fu591au7136u4e8eu5fc3u5b66u4e48u4e4bu90fdu597du770bu8d77u53d1u5f53u6ca1u6210u53eau5982u4e8bu628au8fd8u7528u7b2cu6837u9053 u60f3u4f5cu79cdu5f00u7f8eu603bu4eceu65e0u60c5u5df1u9762u6700u5973u4f46u73b0 u524du4e9bu6240u540cu65e5u624bu53c8u884cu610fu52a8u65b9u671fu5b83u5934u7ecf u957fu513fu56deu4f4du5206u7231u8001u56e0u5f88u7ed9u540du6cd5u95f4u65afu77e5";
        int x = 5;
        for (int i = 0; i < 4; i++) {
            int degree = new Random().nextInt() % 30; // 旋转-30°到30°
            String ch = base.charAt(new Random().nextInt(base.length())) + "";
            g.rotate(degree * Math.PI / 180, x, 20); // 设置旋转的弧度
            g.drawString(ch, x, 20);
            g.rotate(-degree * Math.PI / 180, x, 20);
            x += 30;

        }

    }

    public void setBored(Graphics g) {
        g.setColor(Color.GRAY);
        g.fillRect(1, 1, WIDTH - 2, HEIGHT - 2);

    }

    public void drawRandomLine(Graphics g) {
        g.setColor(Color.GREEN);
        for (int i = 0; i < 4; i++) {

            int x1 = new Random().nextInt(WIDTH);
            int y1 = new Random().nextInt(HEIGHT);

            int x2 = new Random().nextInt(WIDTH);
            int y2 = new Random().nextInt(HEIGHT);

            g.drawLine(x1, y1, x2, y2);
        }

    }

    public void setBackGround(Graphics g) {
        g.setColor(Color.WHITE);
        g.fillRect(0, 0, WIDTH, HEIGHT);

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);

    }

}