jsp登陆验证码

1.JSP页面中设置输入选项和验证码

<form action=login.do" method="post" >
<div class="line_1" >
　　<span class="line_1_span">会员登录</span>
　　<input type="text" class="form-control line_2_input" id="exampleInputAmount" placeholder="手机号" name="username">
</div>
<div class="line_3" >
　　<input type="password" class="form-control line_3_input" id="exampleInputPassword3" placeholder="密码" name="password">
</div>
<div class="line_4">
　　<input type="text"  placeholder="验证码" name="code">
<img id="code" alt="点击刷新" src="code.do" onclick="refreshCode()"/>
</div>
</form>

2.login.jsp中设置JS的方法

<script type="text/javascript">

function refreshCode(){
　　var codeImg = document.getElementById("code");
　　var rand = Math.random();
　　codeImg.src="code.do?random="+rand;
}

</script>

3.配置XML文件

 

<?xml version="1.0" encoding="UTF-8"?><web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">  <display-name>D5.10_yanzhengma</display-name>  <servlet>      <servlet-name>code.do</servlet-name>      <servlet-class>com.phone1000.lq.yanzheng.CodeServlet</servlet-class>  </servlet>  <servlet-mapping>      <servlet-name> code.do</servlet-name>      <url-pattern>/code.do</url-pattern>  </servlet-mapping>  </web-app>

 

4.servlet中代码如下

 

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.imageio.ImageIO;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** *  * @author lq * */public class CodeServlet extends HttpServlet{    public static final int NUMBER = 5;    //1,0,l,容易混淆故去掉这几个字符    String strs = "qwertyuipasdfghjkzxcvbnm23456789一二三四五六七八九";    @Override    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        //创建模板大小        BufferedImage bufferImage = new BufferedImage(100, 40, BufferedImage.TYPE_INT_RGB);        //创建画笔        Graphics graphics = bufferImage.getGraphics();        //调整画笔颜色        graphics.setColor(Color.green);        //设置画笔初始位子和可画区域大小        graphics.fillRect(0, 0, 100, 40);        int size = strs.length();        char[] codes = new char[NUMBER];        Random random = new Random();        graphics.setFont(new Font("宋体", Font.PLAIN, 16));        for (int i=0; i<NUMBER; i++){            int index = random.nextInt(size);            Character c = strs.charAt(index);            codes[i]=c;            graphics.setColor(Color.BLUE);            //画出单个字符大小位置            graphics.drawString(c.toString(),i*20,30);        }        //将生成的验证码字符串保存在session中        req.getSession().setAttribute("code", new String(codes));        //回收资源        graphics.dispose();        //显示图像及格式        ImageIO.write(bufferImage, "png", resp.getOutputStream());            }        @Override    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {        doGet(req,resp);    }}