JSP通过Servlet生成验证码

来源：互联网发布：编程助手编辑：程序博客网时间：2024/06/15 03:18

目录结构：

index.jsp

<%@ page language="java" pageEncoding="utf-8"%> <html><script type="text/javascript"> function refresh(){ document.getElementById("img").src="/VerificationCode/generate?"+Math.random();   //必须加Math.random()，否则由于地址未改变，浏览器不会去请求Servlet} </script><head><title>验证码的使用</title></head><body><form action="/VerificationCode/check" method="post"> 内    容：<input type=text name=message><br> 验证码：<input type=text name=chkmsg><img id="img" src="/VerificationCode/generate"></img><a href="javascript:void(0)" onclick="refresh()">看不清,换一张</a><br><input type=submit value="确定"> <input type=reset value="重置"> </form> </body><html>

GenerateVerificationServlet.java

package com.yourcompany.servlet;import java.awt.Color; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.io.IOException; import java.util.Random; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.sun.image.codec.jpeg.JPEGCodec; import com.sun.image.codec.jpeg.JPEGImageEncoder; public class GenerateVerificationServlet extends HttpServlet{//生成4位在一定取值范围的随机字符 public char[] getRandom() { char[] rand=new char[4]; String str1="0123456789"; String str2="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"; int length1 =str1.length();int length2 =str2.length();Random rd=new Random(); int index1 = rd.nextInt(length1);int index2 = rd.nextInt(length2);int index3 = rd.nextInt(length1);int index4 = rd.nextInt(length2);rand[0]=str1.charAt(index1);rand[1]=str2.charAt(index2);rand[2]=str1.charAt(index3);rand[3]=str2.charAt(index4);return rand; } public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置响应内容类型 response.setContentType("image/jpeg"); //创建字节流 ServletOutputStream sos=response.getOutputStream(); //设置缓冲区 BufferedImage img=new BufferedImage(60,30,4); //在缓冲区中绘图 Graphics g=img.getGraphics(); //调生成4位随机数的方法 char[] rand=this.getRandom(); //保存于session中，以便其它页面可用 request.getSession().setAttribute("chkmsg", new String(rand)); //画3条干扰线 g.setColor(Color.red); g.drawLine(new Random().nextInt(60), new Random().nextInt(60), new Random().nextInt(20), new Random().nextInt(20)); g.drawLine(new Random().nextInt(60), new Random().nextInt(60), new Random().nextInt(60), new Random().nextInt(20)); g.drawLine(new Random().nextInt(80), new Random().nextInt(60), new Random().nextInt(50), new Random().nextInt(20)); //画背景色 g.drawRect(0, 0, 60, 30); g.setColor(Color.blue); //设置前景色 g.setColor(Color.green); g.drawString(""+rand[0], 5, 20); g.drawString(""+rand[1], 20, 10); g.drawString(""+rand[2], 30, 15); g.drawString(""+rand[3], 50, 20); //关闭 g.dispose(); JPEGImageEncoder code=JPEGCodec.createJPEGEncoder(sos); code.encode(img); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{ this.doGet(request, response); } }

CheckVerificationServlet.java

package com.yourcompany.servlet;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class CheckVerificationServlet extends HttpServlet{public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置编码 request.setCharacterEncoding("utf-8"); response.setContentType("text/html;charset=utf-8"); PrintWriter out=response.getWriter(); //获取输入的其他信息 String message = request.getParameter("message"); //获取输入的验证码 String chkmsg = request.getParameter("chkmsg"); //获取正确的验证码String rand = (String) request.getSession().getAttribute("chkmsg");//判断验证码是否正确if(chkmsg!=null && rand!=null){if(chkmsg.equals(rand)) { out.println(message);out.println("成功"); } else { out.println(message);out.println("失败"); } }} public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { this.doGet(request, response); } }

web.xml

<?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">    <servlet>        <servlet-name>GenerateVerificationServlet</servlet-name>        <servlet-class>com.yourcompany.servlet.GenerateVerificationServlet</servlet-class>    </servlet>    <servlet>        <servlet-name>CheckVerificationServlet</servlet-name>        <servlet-class>com.yourcompany.servlet.CheckVerificationServlet</servlet-class>    </servlet>     <servlet-mapping>        <servlet-name>GenerateVerificationServlet</servlet-name>        <url-pattern>/generate</url-pattern>    </servlet-mapping>    <servlet-mapping>        <servlet-name>CheckVerificationServlet</servlet-name>        <url-pattern>/check</url-pattern>    </servlet-mapping></web-app>

0 0