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前台生成验证码

2016-08-29 18:25 162 查看

package cn.gov.csrc.servlet;



import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics;

import java.awt.image.BufferedImage;

import java.io.IOException;

import java.util.Random;



import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;



import com.sun.image.codec.jpeg.JPEGCodec;

import
4000
com.sun.image.codec.jpeg.JPEGImageEncoder;



public class CodeServlet extends HttpServlet {



    /**

     * 产生验证码图片

     */

    public void doGet(HttpServletRequest request, HttpServletResponse response)

            throws ServletException, IOException {

        response.setContentType("image/jpeg");

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

        response.setHeader("Pragma", "No-cache");

        response.setDateHeader("Expires", 0L);

        int width = 80;

        int height = 30;

        BufferedImage image = new BufferedImage(width, height, 1);

        Graphics g = image.getGraphics();

        Random random = new Random();

        g.setColor(getRandColor(200, 250));

        g.fillRect(0, 0, width, height);

        g.setFont(new Font("Arial", 0, 25));

        g.setColor(getRandColor(160, 200));

        for (int i = 0; i < 155; i++) {

            int x = random.nextInt(width + 100);

            int y = random.nextInt(height + 100);

            int xl = random.nextInt(10);

            int yl = random.nextInt(12);

            g.drawOval(x, y, x + xl, y + yl);

        }

        String code = request.getParameter("code");

        String sRand = code;

        for (int i = 0; i < sRand.length(); i++) {

            String rand = sRand.substring(i, i + 1);

            g.setColor(new Color(20 + random.nextInt(110), 20 + random

                    .nextInt(110), 20 + random.nextInt(110)));

            g.drawString(rand, 14 * i + 5, 25);

        }

        g.dispose();

        javax.servlet.ServletOutputStream imageOut = response.getOutputStream();

        JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(imageOut);

        encoder.encode(image);

    }



    private Color getRandColor(int fc, int bc) {

        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);

    }



}

2.Web.xml文件：

[html] view
plain copy

<?xml version="1.0" encoding="UTF-8"?>

<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee"

    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee

    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

    <display-name></display-name>

    <welcome-file-list>

        <welcome-file>index.jsp</welcome-file>

    </welcome-file-list>

    <servlet>

        <servlet-name>CodeServlet</servlet-name>

        <servlet-class>cn.gov.csrc.servlet.CodeServlet</servlet-class>

    </servlet>

    <servlet-mapping>

        <servlet-name>CodeServlet</servlet-name>

        <url-pattern>/CodeServlet</url-pattern>

    </servlet-mapping>

</web-app>

3.index.jsp：

[javascript] view
plain copy

<%@ 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>验证码测试</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">

<script language="javascript" type="text/javascript">

var code ; //在全局定义验证码

function createCode(){

    code = "";

    var codeLength = 5;//验证码的长度

    //所有候选组成验证码的字符，可以用中文

    var selectChar = new Array(0,1,2,3,4,5,6,7,8,9,'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','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');

    for(var i=0;i<codeLength;i++){

        var charIndex = Math.floor(Math.random()*60);

        code +=selectChar[charIndex];

    }

    return code;

}

function validate (){

    var inputCode = document.getElementById("vcode").value.toLowerCase();

    if(inputCode.length <=0){

        alert("请输入验证码！");

        return false;

    }

    else if(inputCode != code.toLowerCase()){

        alert("验证码输入错误！");

        show();//刷新验证码

        return false;

    }else{

        alert("^-^ OK");

        return true;

    }

}

function show(){

        //显示验证码

        document.getElementById("code").src="CodeServlet?code="+createCode();

}

window.onload = function() {

        //document.onload=show();

        show();//页面加载时加载验证码

        //这时无论在ie还是在firefox中，js没有加载完，页面的东西是不会被执行的；

    }

</script>

</head>



<body>

    <form onsubmit="return validate();" action="" method="post">

        <h3>jsp+js+servlet实现验证码</h3>

        <br /> 用户名：<input type="text" name="" /><br /> 请输入验证码： <input

            type="text" id="vcode" style="width: 60;" maxLength="5" /> <img

            src="" id="code" /> <a href="#" mce_href="#"

            onclick="javascript:show();return false;">看不清,换一张!</a><br /> <input

            type="submit" />

    </form>

</body>

</html>

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