20160402javaweb 开发模式

开发案例：

首先，我们确定用xml文件代替数据库，便于测试

建立web工程，基本架构见下图

代码如下：

首先是javabean：User.java

package com.dzq.domian;

import java.io.Serializable;

import com.dzq.exception.MsgException;

public class User implements Serializable{
private String username;
private String password;
private String password2;
private String nickname;
private String email;
public String getUsername() {
    return username;
}
public void setUsername(String username) {
    this.username = username;
}
public String getPassword() {
    return password;
}
public void setPassword(String password) {
    this.password = password;
}
public String getPassword2() {
    return password2;
}
public void setPassword2(String password2) {
    this.password2 = password2;
}
public String getNickname() {
    return nickname;
}
public void setNickname(String nickname) {
    this.nickname = nickname;
}
public String getEmail() {
    return email;
}
public void setEmail(String email) {
    this.email = email;
}
public User(){

}
public User(String username, String password, String password2,
        String nickname, String email) {

    this.username = username;
    this.password = password;
    this.password2 = password2;
    this.nickname = nickname;
    this.email = email;
}
@Override
public String toString() {
    return username+":"+password;
}
public void checkValue() throws MsgException{
    if(username==null||"".equals(username)){
        throw new MsgException("用户名不能为空");
    }
    if(password==null||"".equals(password)){
        throw new MsgException("密码不能为空");
    }
    if(password2==null||"".equals(password2)){
        throw new MsgException("密码不能为空");
    }
    if(!password.equals(password2)){
        throw new MsgException("两次密码输入不一致");
    }
    if(nickname==null||"".equals(nickname)){
        throw new MsgException("昵称不能为空");
    }
    if(email==null||"".equals(email)){
        throw new MsgException("邮箱不能为空");
    }
}

}

数据类XmlUserDao.java

package com.dzq.dao;

import java.util.*;

import org.dom4j.Document;
import org.dom4j.DocumentHelper;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;

import com.dzq.domian.User;
import com.dzq.util.XmlDaoUtils;

public class XmlUserDao {
    /**
     * 根据用户名查找用户
     * @param username 用户名
     * @return 根据用户名找到的用户信息，如果没找到，返回null
     */
public User findUserByUserName(String username){
    Document dom=XmlDaoUtils.getDom();
    Element root=dom.getRootElement();
    List<Element> list=root.selectNodes("//user[@username='"+username+"']");
    if(list.size()>0){
        Element userEle=list.get(0);
        User user=new User();
        user.setUsername(userEle.attributeValue("username"));
        user.setPassword(userEle.attributeValue("password"));
        user.setNickname(userEle.attributeValue("nickname"));
        user.setEmail(userEle.attributeValue("email"));
        return user;
    }else{
        return null;
    }
}
/**
 * 添加用户
 * @param user 要添加用户信息的bean
 */
public void addUser(User user){
    Document dom=XmlDaoUtils.getDom();
    Element root=dom.getRootElement();

    Element userEle=DocumentHelper.createElement("user");
    userEle.setAttributeValue("username", user.getUsername());
    userEle.setAttributeValue("password", user.getPassword());
    userEle.setAttributeValue("nickname", user.getNickname());
    userEle.setAttributeValue("email", user.getEmail());
    root.add(userEle);
    XmlDaoUtils.refXml();
}

/**
 * 根据用户名密码查找用户信息
 * @param username 用户名
 * @param password 密码
 * @return 找到的用户，找不到返回null
 */
public User findUserByUNAndPWD(String username,String password){

    Document dom=XmlDaoUtils.getDom();
    Element root=dom.getRootElement();
    List<Element> list=root.selectNodes("//user[@username='"+username+"'and @password='"+password+"']");
    if(list.size()>0){
        Element userEle=list.get(0);
        User user=new User();
        user.setUsername(userEle.attributeValue("username"));
        user.setPassword(userEle.attributeValue("password"));
        user.setNickname(userEle.attributeValue("nickname"));
        user.setEmail(userEle.attributeValue("email"));
        return user;
    }else{
        return null;
    }

}
}

业务类：UserService.java

package com.dzq.service;

import com.dzq.dao.XmlUserDao;
import com.dzq.domian.User;
import com.dzq.exception.MsgException;

public class UserService {
    private  XmlUserDao dao=new XmlUserDao();
    /**
     * 添加用户
     * @param user
     * @throws MsgException
     */
    public void registUser(User user) throws MsgException{
        if(dao.findUserByUserName(user.getUsername())!=null){
            throw new MsgException("用户名已经存在");
        }
        dao.addUser(user);
    }
    /**
     * 检查用户名是否正确
     * @param username
     * @param password
     */
    public User isUser(String username,String password){
        return dao.findUserByUNAndPWD(username, password);

    }
}

处理异常的类MsgException

package com.dzq.exception;

public class MsgException extends Exception {
public MsgException(){

}

public MsgException(String msg){
    super(msg);
}
}

测试类：XmlUserDaoTest.java

package com.dzq.test;

import org.junit.Test;

import com.dzq.dao.XmlUserDao;
import com.dzq.domian.User;

public class XmlUserDaoTest {
    @Test
public void testfindUserByUserName(){

    XmlUserDao dao=new XmlUserDao();
    User user=dao.findUserByUserName("admin");
    System.out.println(user.toString());
}
    @Test
    public void testfinduserByUNAndPWD(){
        XmlUserDao dao=new XmlUserDao();
        User user=dao.findUserByUNAndPWD("admin", "admin");
        System.out.println(user);
    }
    @Test
    public void testAddUser(){
        XmlUserDao dao=new XmlUserDao();
        User user=new User();
        user.setUsername("xiaoduc");
        user.setPassword("1234");
        user.setNickname("xiaoduc");
        user.setEmail("duxiao@qq.com");
        dao.addUser(user);
    }
}

工具类：XmlDaoUtils.java

package com.dzq.util;

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.UnsupportedEncodingException;

import org.dom4j.Document;
import org.dom4j.Element;
import org.dom4j.io.OutputFormat;
import org.dom4j.io.SAXReader;
import org.dom4j.io.XMLWriter;

public class XmlDaoUtils {
    private static Document dom=null;
    private static String path=XmlDaoUtils.class.getClassLoader().getResource("users.xml").getPath();
   private XmlDaoUtils(){
   }
   static{
       try {
            SAXReader reader=new SAXReader();
             dom= reader.read(path);

        } catch (Exception e) {
            e.printStackTrace();
            throw new RuntimeException();
        }

   }
   public  static Document getDom(){
       return dom;
   } 

   public static void refXml(){
       try {
        XMLWriter writer=new XMLWriter(new FileOutputStream(path),OutputFormat.createPrettyPrint());
        writer.write(dom);
        writer.close();
    } catch (Exception e) {
        e.printStackTrace();
        throw new RuntimeException();
    } 

   }
}

下面是几个servlet

package com.dzq.web;

import java.io.IOException;
import java.net.URLEncoder;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.dzq.domian.User;
import com.dzq.service.UserService;

@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        String username=request.getParameter("username");
        String password=request.getParameter("password");
        UserService service=new UserService();
        User user=service.isUser(username, password);
        if(user==null){
            request.setAttribute("msg", "用户名或者密码错误");
            request.getRequestDispatcher("/login.jsp").forward(request, response);
        }else{
            request.getSession().setAttribute("user", user);
            if("ok".equals(request.getParameter("remname"))){
                Cookie remNameC=new Cookie("remname",URLEncoder.encode(user.getUsername(),"utf-8"));
                remNameC.setPath(request.getContextPath());
                remNameC.setMaxAge(3600*24*30);
                response.addCookie(remNameC);
            }else{
                Cookie remNameC=new Cookie("remname","");
                remNameC.setPath(request.getContextPath());
                remNameC.setMaxAge(0);
                response.addCookie(remNameC);
            }
            response.sendRedirect(request.getContextPath()+"/index.jsp");
        }
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

}

package com.dzq.web;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/LogOutServlet")
public class LogOutServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        if(request.getSession(false)!=null&&request.getSession().getAttribute("user")!=null){
            request.getSession().invalidate();
            response.sendRedirect(request.getContextPath()+"/index.jsp");
        }
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

}

package com.dzq.web;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.beanutils.BeanUtils;

import com.dzq.domian.User;
import com.dzq.exception.MsgException;
import com.dzq.service.UserService;

@WebServlet("/RegistServlet")
public class RegistServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        try {
            UserService service=new UserService();
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        //1。检验验证码
        String valistr=request.getParameter("valistr");
        String valistr2=(String) request.getSession().getAttribute("valistr");
        if(valistr==null||valistr2==null||!valistr.equals(valistr2)){
            request.setAttribute("msg", "验证码不正确");
            request.getRequestDispatcher("/regist.jsp").forward(request, response);
            return;
        }
        //2.封装数据，校验数据
        User user=new User();
        BeanUtils.populate(user, request.getParameterMap());
        user.checkValue();
        service.registUser(user);
        request.getSession().setAttribute("user", user);
        response.getWriter().write("恭喜您注册成功，3秒回到主页");
        response.setHeader("refresh", "3;url="+request.getContextPath()+"/index.jsp");
        }catch(MsgException e){
            request.setAttribute("msg",e.getMessage());
            request.getRequestDispatcher("/regist.jsp").forward(request, response);
            return;
        }catch (Exception e) {
            e.printStackTrace();
            throw new RuntimeException(e);
        }
        //3.调用service方法添加用户

        //4.提示注册成功，3秒跳转主页
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

}

package com.dzq.web;

import java.awt.Color;
import java.awt.Font;
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.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/ValiImg")
public class ValiImg extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        response.setDateHeader("Expires", -1);
        response.setHeader("Cache-Control", "no-cache");
        response.setHeader("Pragma","no-cache");
        //1.在内存中构建一张图片
        int height=30;
        int width=120;
        int xpyl=5;
        int ypyl=22;
        int bang=20;
        BufferedImage img=new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
        //2.获取图像上的画布
        Graphics2D g=(Graphics2D) img.getGraphics();
        //3.设置背景色
        g.setColor(Color.LIGHT_GRAY);
        g.fillRect(0, 0, width, height);
        //4.设置边框
        g.setColor(Color.BLUE);
        g.drawRect(0, 0, width-2, height-2);
        //5.画干扰线
        for(int i=0;i<5;i++){
        g.setColor(Color.RED);
        g.drawLine(randNum(0, width), randNum(0, height), randNum(0, width), randNum(0, height));
        }
        //6.写字
        String base = "\u7684\u4e00\u4e86\u662f\u6211\u4e0d\u5728\u4eba\u4eec\u6709\u6765\u4ed6\u8fd9\u4e0a\u7740\u4e2a\u5730\u5230\u5927\u91cc\u8bf4\u5c31\u53bb\u5b50\u5f97\u4e5f\u548c\u90a3\u8981\u4e0b\u770b\u5929\u65f6\u8fc7\u51fa\u5c0f\u4e48\u8d77\u4f60\u90fd\u628a\u597d\u8fd8\u591a\u6ca1\u4e3a\u53c8\u53ef\u5bb6\u5b66\u53ea\u4ee5\u4e3b\u4f1a\u6837\u5e74\u60f3\u751f\u540c\u8001\u4e2d\u5341\u4ece\u81ea\u9762\u524d\u5934\u9053\u5b83\u540e\u7136\u8d70\u5f88\u50cf\u89c1\u4e24\u7528\u5979\u56fd\u52a8\u8fdb\u6210\u56de\u4ec0\u8fb9\u4f5c\u5bf9\u5f00\u800c\u5df1\u4e9b\u73b0\u5c71\u6c11\u5019\u7ecf\u53d1\u5de5\u5411\u4e8b\u547d\u7ed9\u957f\u6c34\u51e0\u4e49\u4e09\u58f0\u4e8e\u9ad8\u624b\u77e5\u7406\u773c\u5fd7\u70b9\u5fc3\u6218\u4e8c\u95ee\u4f46\u8eab\u65b9\u5b9e\u5403\u505a\u53eb\u5f53\u4f4f\u542c\u9769\u6253\u5462\u771f\u5168\u624d\u56db\u5df2\u6240\u654c\u4e4b\u6700\u5149\u4ea7\u60c5\u8def\u5206\u603b\u6761\u767d\u8bdd\u4e1c\u5e2d\u6b21\u4eb2\u5982\u88ab\u82b1\u53e3\u653e\u513f\u5e38\u6c14\u4e94\u7b2c\u4f7f\u5199\u519b\u5427\u6587\u8fd0\u518d\u679c\u600e\u5b9a\u8bb8\u5feb\u660e\u884c\u56e0\u522b\u98de\u5916\u6811\u7269\u6d3b\u90e8\u95e8\u65e0\u5f80\u8239\u671b\u65b0\u5e26\u961f\u5148\u529b\u5b8c\u5374\u7ad9\u4ee3\u5458\u673a\u66f4\u4e5d\u60a8\u6bcf\u98ce\u7ea7\u8ddf\u7b11\u554a\u5b69\u4e07\u5c11\u76f4\u610f\u591c\u6bd4\u9636\u8fde\u8f66\u91cd\u4fbf\u6597\u9a6c\u54ea\u5316\u592a\u6307\u53d8\u793e\u4f3c\u58eb\u8005\u5e72\u77f3\u6ee1\u65e5\u51b3\u767e\u539f\u62ff\u7fa4\u7a76\u5404\u516d\u672c\u601d\u89e3\u7acb\u6cb3\u6751\u516b\u96be\u65e9\u8bba\u5417\u6839\u5171\u8ba9\u76f8\u7814\u4eca\u5176\u4e66\u5750\u63a5\u5e94\u5173\u4fe1\u89c9\u6b65\u53cd\u5904\u8bb0\u5c06\u5343\u627e\u4e89\u9886\u6216\u5e08\u7ed3\u5757\u8dd1\u8c01\u8349\u8d8a\u5b57\u52a0\u811a\u7d27\u7231\u7b49\u4e60\u9635\u6015\u6708\u9752\u534a\u706b\u6cd5\u9898\u5efa\u8d76\u4f4d\u5531\u6d77\u4e03\u5973\u4efb\u4ef6\u611f\u51c6\u5f20\u56e2\u5c4b\u79bb\u8272\u8138\u7247\u79d1\u5012\u775b\u5229\u4e16\u521a\u4e14\u7531\u9001\u5207\u661f\u5bfc\u665a\u8868\u591f\u6574\u8ba4\u54cd\u96ea\u6d41\u672a\u573a\u8be5\u5e76\u5e95\u6df1\u523b\u5e73\u4f1f\u5fd9\u63d0\u786e\u8fd1\u4eae\u8f7b\u8bb2\u519c\u53e4\u9ed1\u544a\u754c\u62c9\u540d\u5440\u571f\u6e05\u9633\u7167\u529e\u53f2\u6539\u5386\u8f6c\u753b\u9020\u5634\u6b64\u6cbb\u5317\u5fc5\u670d\u96e8\u7a7f\u5185\u8bc6\u9a8c\u4f20\u4e1a\u83dc\u722c\u7761\u5174\u5f62\u91cf\u54b1\u89c2\u82e6\u4f53\u4f17\u901a\u51b2\u5408\u7834\u53cb\u5ea6\u672f\u996d\u516c\u65c1\u623f\u6781\u5357\u67aa\u8bfb\u6c99\u5c81\u7ebf\u91ce\u575a\u7a7a\u6536\u7b97\u81f3\u653f\u57ce\u52b3\u843d\u94b1\u7279\u56f4\u5f1f\u80dc\u6559\u70ed\u5c55\u5305\u6b4c\u7c7b\u6e10\u5f3a\u6570\u4e61\u547c\u6027\u97f3\u7b54\u54e5\u9645\u65e7\u795e\u5ea7\u7ae0\u5e2e\u5566\u53d7\u7cfb\u4ee4\u8df3\u975e\u4f55\u725b\u53d6\u5165\u5cb8\u6562\u6389\u5ffd\u79cd\u88c5\u9876\u6025\u6797\u505c\u606f\u53e5\u533a\u8863\u822c\u62a5\u53f6\u538b\u6162\u53d4\u80cc\u7ec6";
        StringBuffer buffer=new StringBuffer();

        for(int i=0;i<4;i++){
            g.setColor(new Color(randNum(0, 255),randNum(0, 255),randNum(0, 255)));
            g.setFont(new Font("黑体",Font.BOLD,bang));
            int r=randNum(-45, 45);
            g.rotate(1.0*r/180*Math.PI,xpyl+i*30, ypyl);
            String s=base.charAt(randNum(0, base.length()-1))+"";
            buffer.append(s);
            g.drawString(s, xpyl+i*30, ypyl);
            g.rotate(1.0*-r/180*Math.PI,xpyl+i*30, ypyl);
        }
        request.getSession().setAttribute("valistr", buffer.toString());
        System.out.println(buffer.toString());
        //将图片输出到浏览器
        ImageIO.write(img, "jpg", response.getOutputStream());

    }
    private Random rand=new Random();
    private int randNum(int begin,int end){

     return rand.nextInt((end-begin)+begin);        

    }
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    doGet(request, response);
    }
}

自定义标签类：

package com.dzq.tag;

import java.io.IOException;
import java.net.URLDecoder;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.SimpleTagSupport;

public class URLDEcoderTag extends SimpleTagSupport {
    private String content;
    private String encode;

public void setContent(String content) {
    this.content = content;
}

public void setEncode(String encode) {
    this.encode = encode;
}

@Override
public void doTag() throws JspException, IOException {
    String str=URLDecoder.decode(content, encode==null?"utf-8":encode);
    getJspContext().getOut().write(str);

}

}

自定义标签的tld文件UserTag.tld

<?xml version="1.0" encoding="UTF-8"?>
<taglib version="2.0" xmlns="http://java.sun.com/xml/ns/j2ee"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd">
 <tlib-version>1.0</tlib-version>
 <short-name>UserTag</short-name>
 <uri>http://www.dzq.com/UserTag</uri>
 <tag>
  <name>URLDecoder</name>
  <tag-class>com.dzq.tag.URLDEcoderTag</tag-class>
  <body-content>empty</body-content>
  <attribute>
   <name>content</name>
   <required>true</required>
   <rtexprvalue>true</rtexprvalue>
   <type>java.lang.String</type>
  </attribute>
  <attribute>
   <name>encode</name>
   <required>false</required>
   <rtexprvalue>true</rtexprvalue>
   <type>java.lang.String</type>
  </attribute>
 </tag>
</taglib>

下面是存储信息的xml文件users.xml

<?xml version="1.0" encoding="UTF-8"?>
<users>
    <user username="admin" password="admin" nickname="admin" email="admin@qq.com" />
</users>

以下是jsp页面：

index.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
    <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<html>
<head>
</head>
<body>
<h1>我的网站</h1><hr>
<c:if test="${sessionScope.user!=null}">
欢迎回来！${sessionScope.user.username }<a href="${pageContext.request.contextPath }/LogOutServlet">注销</a>
</c:if>

<c:if test="${sessionScope.user==null}">
游客，欢迎你！<a href="${pageContext.request.contextPath }/regist.jsp">注册</a>|<a href="${pageContext.request.contextPath }/login.jsp">登录</a>
</c:if>
</body>
</html>

login.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
    <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
    <%@taglib uri="http://www.dzq.com/UserTag" prefix="UserTag" %>
<html>
<head>

</head>
<body>
<div align="center">
<h1>我的网站_登录</h1><hr>
<font color="red">${msg }</font>
<form action="${pageContext.request.contextPath }/LoginServlet" method="post">
<table border="1">
       <tr>
          <td>用户名：</td>

          <td><input type="text" name="username" value="<UserTag:URLDecoder content="${cookie.remname.value }" encode="utf-8"/>"/></td>
       </tr>
       <tr>
          <td>密码：</td>
          <td><input type="password" name="password"/></td>
       </tr>
       <tr>
          <td><input type="submit" value="登录"/></td>
          <td><input type="checkbox" value="ok" name="remname"
          <c:if test="${cookie.remname!=null }">
          checked="checked"
          </c:if>
          />记住用户名</td>
       </tr>
</table>
</form>
</div>
</body>
</html>

regist.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
    <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<html>
<head>
<script type="text/javascript">
function changeImg(img){
    img.src=img.src+"?time="+new Date().getTime();
}
</script>
</head>
 <font color="red" >${msg }</font>
<body>
<div align="center">
<h1>我的网站_注册</h1>
<form action="${pageContext.request.contextPath }/RegistServlet" method="post">
<table border="1">
    <tr>
        <td>用户名：</td>
        <td><input type="text" name="username" value="${param.username }"/></td>
    <tr/>
     <tr>
        <td>密码：</td>
        <td><input type="password" name="password" /></td>
    <tr/>
     <tr>
        <td>确认密码：</td>
        <td><input type="password" name="password2" /></td>
    <tr/>
     <tr>
        <td>昵称：</td>
        <td><input type="text" name="nickname" value="${param.nickname }"/></td>
    <tr/>
     <tr>
        <td>邮箱</td>
        <td><input type="email" name="email" value="${param.email }"/></td>
    <tr/>
     <tr>
        <td>验证码：</td>
        <td><input type="text" name="valistr" /></td>
    <tr/>
     <tr>
        <td><input type="submit" value="注册"/></td>
        <td><img src="${pageContext.request.contextPath }/ValiImg" style="cursor: pointer;" onclick="changeImg(this)"></td>
    <tr/>

</table>
</form>
</div>
</body>
</html

运行截图：

采用了cookie 记住用户名

源码下载地址