JavaWeb-Servlet-通过servlet生成验证码图片

BufferedImage类

创建一个BufferImage servlet，用来生成验证码图片：

package com.fpc;

import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics;

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.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class BufferImage extends HttpServlet {

    public static final int WIDTH = 120;//生成图片的宽度

    public static final int HEIGHT = 30;//生成图片的高度

    public static final int WORDS_NUMBER = 5;//验证码中字符的个数

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        // TODO Auto-generated method stub

        this.doPost(req, resp);

    }

    @Override

    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        // TODO Auto-generated method stub

        String createTypeFlag = req.getParameter("createTypeFlag");//接收客户端传递的createTypeFlag标识

        //在内存中创建一张图片

        BufferedImage bi = new BufferedImage(WIDTH,HEIGHT,BufferedImage.TYPE_3BYTE_BGR);

        //得到图片

        Graphics g = bi.getGraphics();

        //设置图片的背景色

        setBackGround(g);

        //设置图片的边框

        setBorder(g);

        //在图片上画干扰线

        drawRandomLine(g);

        //在图片上放上随机字符

        String randomString = this.drawRandomNum((Graphics2D)g, createTypeFlag);

        //将随机数存在session中

        req.getSession().setAttribute("checkcode", randomString);

        //设置响应头通知浏览器以图片的形式打开

        resp.setContentType("image/jpeg");

        //设置响应头控制浏览器不要缓存

        resp.setDateHeader("expries", -1);

        resp.setHeader("Cache-Control", "no-cache");

        resp.setHeader("Pragma", "no-cache");

        //将图片传给浏览器

        ImageIO.write(bi, "jpg", resp.getOutputStream());

    }

    //设置图片背景色

    //@param g

    private void setBackGround(Graphics g) {

        //设置颜色

        g.setColor(Color.WHITE);

        //填充区域

        g.fillRect(0, 0, WIDTH, HEIGHT);

    }

    /*

     * 设置图片的边框

     * @param g

     * */

    private void setBorder(Graphics g) {

        //设置边框颜色

        g.setColor(Color.BLUE);

        //边框区域

        g.drawRect(1, 1, WIDTH - 2, HEIGHT -2);

    }

    /*

     * 在图片上画随机线条

     * @param g

     * */

    private void drawRandomLine(Graphics g) {

        //设置颜色

        g.setColor(Color.GREEN);

        //设置线条个数并画线

        for ( int i = 0 ; i < 3 ; 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);

        }

    }

    /*

     * 在图片上画随机字符

     * @param g

     * @param createTypeFlag

     * @return String

     * */

    private String drawRandomNum(Graphics g,String createTypeFlag) {

        //设置颜色

        g.setColor(Color.RED);

        g.setFont(new Font("宋体",Font.BOLD,20));

        //数字字母的组合

        String baseNumLetter = "0123456789ABCDEFGHJKLMNOPQRSTUVWXYZ";

        String baseNum = "0123456789";

        String baseLetter = "ABCDEFGHJKLMNOPQRSTUVWXYZ";

        if ( createTypeFlag != null  && createTypeFlag.length() > 0 ) {

            if( createTypeFlag.equals("nl") ) {

                //截取数字和字母的组合

                return createRandomChar((Graphics2D) g,baseNumLetter);

            } else if ( createTypeFlag.equals("n") ) {

                //截取数字的组合

                return createRandomChar((Graphics2D) g,baseNum);

            } else if ( createTypeFlag.equals("l") ) {

                //截取字母的组合

                return createRandomChar((Graphics2D) g,baseLetter);

            }

        } else {

            //截取数字和字母的组合

            return createRandomChar((Graphics2D) g,baseNumLetter);

        }

        return "";

    }

    /*

     * 创建随机字符

     * @param g

     * @param baseChar

     * @return String

     * */

    private String createRandomChar(Graphics2D g , String baseChar) {

        StringBuffer b = new StringBuffer();

        int x = 5;

        String ch = "";

        for ( int i = 0 ; i < WORDS_NUMBER ; i++ ) {

            //设置字体的旋转角度

            int degree = new Random().nextInt() % 30;

            ch = baseChar.charAt(new Random().nextInt(baseChar.length())) + "";

            b.append(ch);

            //正向角度

            g.rotate(degree  * Math.PI / 180 , x,20);

            g.drawString(ch, x, 20);

            //反向角度

            g.rotate(-degree  * Math.PI / 180 , x,20);

            x+=30;

        }

        return b.toString();

    }

}

运行结果：

在Form表单中使用验证码图片

index.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

  <head>

    <title>在Form表单中使用验证码</title>

    <script type="text/javascript">

    //刷新验证码

    function changeImg(){

        document.getElementById("validateCodeImg").src="data:image/checkcode?"+Math.random();

    }

    </script>

  </head>

  <body>

        <form action="/image/checkcode" method="post"> 验证码：<input type="text" name="validateCode"/>

            <img alt="验证码看不清，换一张" src="data:image/checkcode" id="validateCodeImg" onclick="changeImg()">

            <a href="javascript:void(0)" onclick="changeImg()">看不清，换一张</a>

            <br/>

            <input type="submit" value="提交">

        </form>

  </body>

</html>

运行结果：

服务器端对form表单提交上来的验证码处理

index.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

  <head>

    <title>在Form表单中使用验证码</title>

    <script type="text/javascript">

    //刷新验证码

    function changeImg(){

        document.getElementById("validateCodeImg").src="data:image/checkcode?"+Math.random();

    }

    </script>

  </head>

  <body>

        <form action="service/checkcode" method="post"> 验证码：<input type="text" name="validateCode"/>

            <img alt="验证码看不清，换一张" src="data:image/checkcode" id="validateCodeImg" onclick="changeImg()">

            <a href="javascript:void(0)" onclick="changeImg()">看不清，换一张</a>

            <br/>

            <input type="submit" value="提交">

        </form>

  </body>

</html>

CheckServlet:

package com.fpc;

import java.io.IOException;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class CheckServlet extends HttpServlet {

    @Override

    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

    }

    @Override

    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        // TODO Auto-generated method stub

        // TODO Auto-generated method stub

                String clientCheckcode = req.getParameter("validateCode");

                String serverCheckcode = (String) req.getSession().getAttribute("checkcode");

                if ( clientCheckcode.contentEquals(serverCheckcode) ) {

                    System.out.println("验证通过");

                } else {

                    System.out.println("验证失败");

                }

    }

}

运行结果：

巴特西

JavaWeb-Servlet-通过servlet生成验证码图片

BufferedImage类

在Form表单中使用验证码图片

服务器端对form表单提交上来的验证码处理

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