生成图片验证码

package cn.itcast.estore.web.servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
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;

/**
 * 验证码生成程序
 * 
 * 
 * 
 */
 @WebServlet("/CheckImgServlet")
public class CheckImgServlet extends HttpServlet {

    // 集合中保存所有成语
    private List<String> words = new ArrayList<String>();

    @Override
    public void init() throws ServletException {
        // 初始化阶段，读取new_words.txt
        // web工程中读取 文件，必须使用绝对磁盘路径
        String path = getServletContext().getRealPath("/WEB-INF/new_words.txt");
        try {
            BufferedReader reader = new BufferedReader(new FileReader(path));
            String line;
            while ((line = reader.readLine()) != null) {
                words.add(line);
            }
            reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 禁止缓存
        // response.setHeader("Cache-Control", "no-cache");
        // response.setHeader("Pragma", "no-cache");
        // response.setDateHeader("Expires", -1);

        int width = 120;
        int height = 30;

        // 步骤一 绘制一张内存中图片
        BufferedImage bufferedImage = new BufferedImage(width, height,
                BufferedImage.TYPE_INT_RGB);

        // 步骤二 图片绘制背景颜色 ---通过绘图对象
        Graphics graphics = bufferedImage.getGraphics();// 得到画图对象 --- 画笔
        // 绘制任何图形之前 都必须指定一个颜色
        graphics.setColor(getRandColor(200, 250));
        graphics.fillRect(0, 0, width, height);

        // 步骤三 绘制边框
        graphics.setColor(Color.WHITE);
        graphics.drawRect(0, 0, width - 1, height - 1);

        // 步骤四 四个随机数字
        Graphics2D graphics2d = (Graphics2D) graphics;
        // 设置输出字体
        graphics2d.setFont(new Font("宋体", Font.BOLD, 18));

        Random random = new Random();// 生成随机数
        int index = random.nextInt(words.size());
        String word = words.get(index);// 获得成语

        // 定义x坐标
        int x = 10;
        for (int i = 0; i < word.length(); i++) {
            // 随机颜色
            graphics2d.setColor(new Color(20 + random.nextInt(110), 20 + random
                    .nextInt(110), 20 + random.nextInt(110)));
            // 旋转 -30 --- 30度
            int jiaodu = random.nextInt(60) - 30;
            // 换算弧度
            double theta = jiaodu * Math.PI / 180;

            // 获得字母数字
            char c = word.charAt(i);

            // 将c 输出到图片
            graphics2d.rotate(theta, x, 20);
            graphics2d.drawString(String.valueOf(c), x, 20);
            graphics2d.rotate(-theta, x, 20);
            x += 30;
        }

        // 将验证码内容保存session
        request.getSession().setAttribute("checkcode_session", word);

        // 步骤五 绘制干扰线
        graphics.setColor(getRandColor(160, 200));
        int x1;
        int x2;
        int y1;
        int y2;
        for (int i = 0; i < 30; i++) {
            x1 = random.nextInt(width);
            x2 = random.nextInt(12);
            y1 = random.nextInt(height);
            y2 = random.nextInt(12);
            graphics.drawLine(x1, y1, x1 + x2, x2 + y2);
        }

        // 将上面图片输出到浏览器 ImageIO
        graphics.dispose();// 释放资源
        ImageIO.write(bufferedImage, "jpg", response.getOutputStream());

    }

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

    /**
     * 取其某一范围的color
     * 
     * @param fc
     *            int 范围参数1
     * @param bc
     *            int 范围参数2
     * @return Color
     */
    private Color getRandColor(int fc, int bc) {
        // 取其随机颜色
        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);
    }

}

在界面获取时，

<img title="" alt="" src="CheckImgServlet" />       <!--将servlet的地址输入进来-->

即可获取

代码2

package com.mhss.servlet;

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

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

/**
 * 通过二维画图 生成验证码图片
 * @author 梦幻逝水
 *
 */
public class ValidateServlet extends HttpServlet {

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    /** 验证码图片的宽度 */
    private int width = 150;
    /** 验证码图片的高度 */
    private int height = 55;
    /** 验证码字符个数 */
    private int codeCount = 4;

    // 字符间距
    private int x = 0;
    // 字体高度
    private int fontHeight;
    private int codeY;

    char[] codeSequence = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
            'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W',
            'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };

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

    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        this.service(request, response);
    }

    public void init() {
        // 宽度
        String strWidth = this.getInitParameter("width");
        // 高度
        String strHeight = this.getInitParameter("height");
        // 字符个数
        String strCodeCount = this.getInitParameter("codeCount");
        if (strWidth != null && strWidth.length() != 0) {
            width = Integer.parseInt(strWidth);
        }
        if (strHeight != null && strHeight.length() != 0) {
            height = Integer.parseInt(strHeight);
        }
        if (strCodeCount != null && strCodeCount.length() != 0) {
            codeCount = Integer.parseInt(strCodeCount);
        }
        // 计算验证码在图片中位置
        x = width / (codeCount + 1);
        fontHeight = height - 2;
        codeY = height - 4;
    }

    /**
     * 产生随机码图片
     */
    public void service(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 产生图片
        BufferedImage bi = new BufferedImage(width, height,
                BufferedImage.TYPE_INT_RGB);
        // 网图片中加载图片的工具
        Graphics2D g = bi.createGraphics();
        // 添加背景
        g.setColor(Color.WHITE);
        g.fillRect(0, 0, width, height);
        // 创建字体
        Font font = new Font("Fixedsys", Font.PLAIN | Font.BOLD, fontHeight);
        // 设置字体
        g.setFont(font);
        // 画边框
        g.setColor(Color.black);
        g.drawRect(0, 0, width - 1, height - 1);
        // 画干扰线
        Random random = new Random();
        g.setColor(Color.PINK);
        for (int i = 0; i < 100; i++) {
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int xl = random.nextInt(12);
            int yl = random.nextInt(12);
            g.drawLine(x, y, x + xl, y + yl);

        }
        StringBuffer sbnumber = new StringBuffer();
        // 生成随机码
        for (int i = 0; i < this.codeCount; i++) {
            String strRand = String.valueOf(codeSequence[random.nextInt(36)]);
            // 随机产生颜色分量来创建颜色
            int red = random.nextInt(255);
            int green = random.nextInt(255);
            int blue = random.nextInt(255);
            //
            g.setColor(new Color(red, green, blue));
            g.drawString(strRand, (i + 1) * x - 6, codeY);
            // 把每次生成的验证码放在缓冲区
            sbnumber.append(strRand);

        }
        // 把生成的验证码放在session中
        request.getSession().setAttribute("sbnumber", sbnumber.toString());
        // 把最终生成 图片 响应到页面去
        response.setContentType("image/jpeg");
        ServletOutputStream sos = response.getOutputStream();
        // 把图片 发送出去
        ImageIO.write(bi, "jpeg", sos);
        sos.close();
    }
}

页面引用时  同样通过

<img title="" alt="" src="CheckImgServlet" />       <!--将servlet的地址输入进来-->

获取:页面代码如下

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'index.jsp' starting page</title>
    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">    
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->
    <script type="text/javascript"> 
         function newCode(){
             var  today = new  Date();
             document.getElementById("imgNumber").src="ValidateServlet?tm="+today.getTime();
         }
    </script>
  </head>
  
  <body>
  <form action="">&nbsp; 
   验证码： <input type="text" name="text" />
   <img src="ValidateServlet" id="imgNumber"/>
     <a href="javascript:newCode()">看不清,换一张</a>
  </form>
  <br/>
  </body>
</html>