登录 图形验证码
[html]
<%@ 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>
</head>
<form action="./LoginServlet" method="post">
<body>
员工信息录入<br/>
用户名：<input type="text" value="" name="username" /> <br/>
密码：<input type="password" name="psw"/> <br/>
验证码：<input name="checkcode" type="text" classs="big-input" maxlength="20" value="" /><br/>
<img src="${pageContext.request.contextPath }/ImageServlet" onclick="nextPic();" id="pic" title="看不清，再来一张" /><br/>
保存用户名和密码<input type="checkbox" name="save" value="yes" /><br/>
<input type="submit" value="保存" />
</body>
<script type="text/javascript">
function nextPic(){
var picStr=document.getElementById("pic");
//使用随机数
// picStr.src="${pageContext.request.contextPath }/ImageServlet?"+Math.random();
//使用时间戳
picStr.src="${pageContext.request.contextPath }/ImageServlet?"+Date.parse(new Date());
}
</script>
</form>
</html>
ImageServlet:
[java]
package aaa;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.PrintWriter;
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;
import javax.servlet.http.HttpSession;
public class ImageServlet extends HttpServlet {
private int width=85;
private int height=30;
//定义验证码的使用的字母和数字
private char[] charSeq="abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".toCharArray();
private int codeCount=4;
//定义验证码的基线
private int codeX;
private int codeY;
public ImageServlet() {
super();
}
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request,response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
//PrintWriter out = response.getWriter();
HttpSession session=request.getSession();
/*
* BufferedImage描述具有可以访问图像缓冲区的image
* Graphics类是所有图形上下文
*/
BufferedImage image=new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
Graphics g=image.getGraphics();
//将此图形上下文的当前颜色设置为指定颜色
g.setColor(Color.white);
g.fillRect(0, 0, width, height);
//设置边框的yans
g.setColor(Color.black);
g.drawRect(0, 0, width-1, height-1);
//生成验证码
Random random=new Random();
String randstr="";
for(int i=1;i<=codeCount;i++){
//随即获取验证码
String rand=String.valueOf(charSeq[random.nextInt(charSeq.length)]);
System.out.println("rand= "+rand);
randstr=randstr+rand;
g.setColor(Color.blue);
g.setFont(new Font("宋体",Font.BOLD,30));
g.drawString(rand, codeX*i, codeY);
}
System.out.println("randstr= "+randstr);
//把randstr放置到session中
session.setAttribute("checkKey", randstr);
//设置干扰点
for(int i=0;i<155;i++){
int x=random.nextInt(width);
int y=random.nextInt(height);
g.setColor(Color.red);
g.drawOval(x, y, 0, 0);
}
//释放资源
g.dispose();
HttpServletResponse res=(HttpServletResponse)response;
//设定网页的到期时间，一旦过期则必须到服务器上重新调用
res.setDateHeader("Expires", -1);
//Cache-Control 指定请求和响应应遵循的缓存机制 no-cache指示请求或响应消息是不能缓存的
res.setHeader("Cache-Control", "no-cache");
//用于设定禁止浏览器从本地缓存中调用页面内容，设定后一旦离开页面就无法从Cache中再调出
res.setHeader("Pragma", "no-cache");
ImageIO.write(image, "jpeg", response.getOutputStream());
}
public void init() throws ServletException {
this.codeX=width/(codeCount+2);
this.codeY=height;
}
}
LoginServlet:
[java]
package aaa;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class LoginServlet extends HttpServlet {
public LoginServlet() {
super();
}
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request,response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//request.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
HttpSession session=request.getSession();
String username=request.getParameter("username");
String checkcode=request.getParameter("checkcode");
String checkKey=(String)session.getAttribute("checkKey");
if(checkcode.equals(checkKey)){
System.out.println("允许登录");
}else{
System.out.println("重新登录");
}
System.out.println("username= "+username);
request.getRequestDispatcher("/purview.jsp").forward(request, response);
}
public void init() throws ServletException {
}
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