本文进行model2模式的实战--登录模块的实现
采用MVC模式开发，具体模块分别如下：
JavaBean组件（Model）
User：封装用户对象
UserDao：封装用户数据库操作
DataBaseUtil：数据库连接工具类
JSP页面（View）
index.jsp：主页
reg.jsp：用户注册页面
login.jsp：用户登录页面
message.jsp：提示信息页面
Servlet（Controller）
RegServlet：用户注册Servlet类
LoginServlet：用户登录Servlet类
UserExitServlet：用户退出Servlet类
JavaBean设计
1、用户实体对象（User类）
User.java
public class User { private int id; private String username; private String password; private String sex; private String tel; private String photo; private String email; public int getId() { return id; } public void setId(int id) { this.id = id; } 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 getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } public String getTel() { return tel; } public void setTel(String tel) { this.tel = tel; } public String getPhoto() { return photo; } public void setPhoto(String photo) { this.photo = photo; } public String getEmail() { return email; } public void setEmail(String email) { this.email = email; } }
2、数据库连接工具类
DataBaseUtil.java
package com.wuyudong.util; import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; public class DataBaseUtil { public static ConnectiongetConnection() { Connectionconn = null; try { Class.forName("com.mysql.jdbc.Driver"); String url = "jdbc:mysql://localhost:3306/db_database05"; conn = DriverManager.getConnection(url, "root", "wuyudong"); } catch (Exception e) { e.printStackTrace(); } return conn; } public static void closeConnection(Connectionconn) { if (conn != null) { try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } }
3、用户数据库操作
与用户相关的数据库操作方法被封装在UserDao类中
UserDao.java
package com.wuyudong.model.dao; import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import com.wuyudong.model.User; import com.wuyudong.util.DataBaseUtil; public class UserDao { public boolean userIsExist(String username) { Connectionconn = DataBaseUtil.getConnection(); String sql = "select * from tb_user where username=?"; try { // 获取PreparedStatement对象 PreparedStatementps = conn.prepareStatement(sql); // 对用户对象属性赋值 ps.setString(1, username); // 执行查询获取结果集 ResultSetrs = ps.executeQuery(); // 判断结果集是否有效 if (!rs.next()) { return true; } rs.close(); ps.close(); } catch (Exception e) { e.printStackTrace(); } finally { DataBaseUtil.closeConnection(conn); } return false; } public void saveUser(Useruser) { Connectionconn = DataBaseUtil.getConnection(); String sql = "insert into tb_user(username,password,sex,tel,photo,email)values(?,?,?,?,?,?)"; try { PreparedStatementps = conn.prepareStatement(sql); ps.setString(1, user.getUsername()); ps.setString(2, user.getPassword()); ps.setString(3, user.getSex()); ps.setString(4, user.getTel()); ps.setString(5, user.getPhoto()); ps.setString(6, user.getEmail()); ps.executeUpdate(); ps.close(); } catch (Exception e) { e.printStackTrace(); } finally { DataBaseUtil.closeConnection(conn); } } public Userlogin(String username, String password) { Useruser=null; Connectionconn=DataBaseUtil.getConnection(); String sql="select * from tb_user where username=? and password=?"; try{ PreparedStatementps=conn.prepareStatement(sql); ps.setString(1, username); ps.setString(2, password); ResultSetrs=ps.executeQuery(); if(rs.next()){ user=new User(); user.setId(rs.getInt("id")); user.setUsername(rs.getString("username")); user.setPassword(rs.getString("password")); user.setSex(rs.getString("sex")); user.setTel(rs.getString("tel")); user.setPhoto(rs.getString("photo")); user.setEmail(rs.getString("email")); } rs.close(); ps.close(); } catch(Exception e){ e.printStackTrace(); }finally{ DataBaseUtil.closeConnection(conn); } return user; } }
实现过程
1、用户注册
（1）创建RegServlet类对用户的注册进行处理
RegServlet.java
package com.wuyudong.service; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.wuyudong.model.User; import com.wuyudong.model.dao.UserDao; public class RegServlet extends HttpServlet { private static final long serialVersionUID = -409981562297982450L; @Override protected void doPost(HttpServletRequestrequest, HttpServletResponseresponse) throws ServletException, IOException { // TODO Auto-generated method stub String username = request.getParameter("username"); String password = request.getParameter("password"); String sex = request.getParameter("sex"); String photo = request.getParameter("photo"); String tel = request.getParameter("tel"); String email = request.getParameter("email"); UserDaouserDao = new UserDao(); if (username != null && !username.isEmpty()) { if (userDao.userIsExist(username)) { // 实例化一个对象 Useruser = new User(); // 对用户对象中的属性赋值 user.setUsername(username); user.setPassword(password); user.setSex(sex); user.setPhoto(photo); user.setTel(tel); user.setEmail(email); // 保存用户注册信息 userDao.saveUser(user); request.setAttribute("info", "恭喜，注册成功！<br>"); } else { request.setAttribute("info", "错误：此用户名已存在！"); } } // 转发到message.jsp页面 request.getRequestDispatcher("message.jsp").forward(request, response); } }
（2）创建视图层
reg.jsp
<%@ page language="java" contentType="text/html" pageEncoding="GBK"%> <!DOCTYPEHTMLPUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>用户注册</title> <linkrel="stylesheet" type="text/css" href="images/styles.css"> <scripttype="text/javascript"> function reg(form){ if(form.username.value == ""){ alert("用户不能为空！"); return false; } if(form.password.value == ""){ alert("密码不能为空！"); return false; } if(form.repassword.value == ""){ alert("确认密码不能为空！"); return false; } if(form.password.value != form.repassword.value){ alert("两次密码输入不一致！"); return false; } if(form.tel.value == ""){ alert("联系电话不能为空！"); return false; } if(form.email.value == ""){ alert("电子邮箱不能为空！"); return false; } } function change(){ var photo = document.getElementById("photo"); var photoImg = document.getElementById("photoImg"); photoImg.src = photo.value; } </script> </head> <body> <divalign="center"> <divclass="div1"> <divclass="top">用户登录</div> <divclass="bottom"> <divclass="div2"> <ul> <li><a href="reg.jsp">用户注册</a></li> <li><a href="login.jsp">用户登录</a></li> <li><a href="message.jsp">当前用户</a></li> <li><a href="UserExitServlet">用户退出</a></li> </ul> </div> <divclass="div3"> <formaction="RegServlet" method="post" onsubmit="return reg(this);"> <tablealign="center" width="450" border="0"> <tr> <tdalign="right">用户名：</td> <td> <inputtype="text" name="username"> </td> </tr> <tr> <tdalign="right">密 码：</td> <td> <inputtype="password" name="password"> </td> </tr> <tr> <tdalign="right">确认密码：</td> <td> <inputtype="password" name="repassword"> </td> </tr> <tr> <tdalign="right">性 别：</td> <td> <inputtype="radio" name="sex" value="男" checked="checked">男 <inputtype="radio" name="sex" value="女">女 </td> </tr> <tr> <tdalign="right">头 像：</td> <td> <selectname="photo" id="photo" onchange="change();"> <optionvalue="images/1.gif" selected="selected">头像一</option> <optionvalue="images/2.gif">头像二</option> </select> <imgid="photoImg" src="images/1.gif"> </td> </tr> <tr> <tdalign="right">联系电话：</td> <td> <inputtype="text" name="tel"> </td> </tr> <tr> <tdalign="right">电子邮箱：</td> <td> <inputtype="text" name="email"> </td> </tr> <tr> <tdcolspan="2" align="center"> <inputtype="submit" value="注 册"> <inputtype="reset" value="重 置"> </td> </tr> </table> </form> </div> </div> </div> </div> </body> </html>
2、用户登录
（1）创建LoginServlet类对用户的登录进行处理
LoginServlet.java
package com.wuyudong.service; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import com.wuyudong.model.User; import com.wuyudong.model.dao.UserDao; public class LoginServlet extends HttpServlet { private static final long serialVersionUID = 1829331482363438909L; @Override protected void doPost(HttpServletRequestrequest, HttpServletResponseresponse) throws ServletException, IOException { // 获取用户名 String username = request.getParameter("username"); // 获取密码 String password = request.getParameter("password"); // 实例化DataDao对象 UserDaouserDao = new UserDao(); // 实例化User对象 Useruser = userDao.login(username, password); if (user != null) { // 将用户对象放入Session中 request.getSession().setAttribute("user", user); request.getRequestDispatcher("message.jsp").forward(request, response); } else { // 登录失败 request.setAttribute("info", "错误：用户名或密码错误！"); request.getRequestDispatcher("message.jsp").forward(request, response); } } }
（2）创建视图
login.jsp
<%@ page language="java" contentType="text/html" pageEncoding="GBK"%> <!DOCTYPEHTMLPUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>用户登录</title> <linkrel="stylesheet" type="text/css" href="images/styles.css"> <scripttype="text/javascript"> function login(form){ if(form.username.value == ""){ alert("用户不能为空！"); return false; } if(form.password.value == ""){ alert("密码不能为空！"); return false; } } </script> </head> <body> <divalign="center"> <divclass="div1"> <divclass="top">用户注册</div> <divclass="bottom"> <divclass="div2"> <ul> <li><a href="reg.jsp">用户注册</a></li> <li><a href="login.jsp">用户登录</a></li> <li><a href="message.jsp">当前用户</a></li> <li><a href="UserExitServlet">用户退出</a></li> </ul> </div> <divclass="div3"> <formaction="LoginServlet" method="post" onSubmit="return login(this);"> <tablealign="center" width="300" border="0" class="tb1"> <tr> <tdalign="right">用户名：</td> <td> <inputtype="text" name="username"> </td> </tr> <tr> <tdalign="right">密 码：</td> <td> <inputtype="password" name="password"> </td> </tr> <tr> <tdcolspan="2" align="center" height="50"> <inputtype="submit" value="登 录"> <inputtype="reset" value="重 置"> </td> </tr> </table> </form> </div> </div> </div> </div> </body> </html>
3、用户退出
用户退出请求由UserExitServlet类进行处理
UserExitServlet.jsp
package com.wuyudong.service;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import org.apache.catalina.User;
public class UserExitServlet extends HttpServlet {
private static final long serialVersionUID = -1249523020574432559L;
@Override
protected void doPost(HttpServletRequestrequest,
HttpServletResponseresponse) throws ServletException, IOException {
// 获取session
HttpSessionsession = request.getSession();
// 获取用户对象
Useruser = (User) session.getAttribute("user");
// 判断用户是否有效
if (user != null) {
// 将用户对象逐出Session
session.removeAttribute("user");
// 设置提示信息
session.setAttribute("info", user.getUsername() + "已经成功退出！");
}
// 转发到message.jsp页面
request.getRequestDispatcher("message.jsp").forward(request, response);
}
}
4、提示信息页面
程序在处理业务请求后，需要告知用户的处理结果
message.jsp
<%@ page language="java" contentType="text/html" pageEncoding="GBK"%> <%@ page import="com.wuyudong.model.User" %> <!DOCTYPEHTMLPUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>提示信息</title> <linkrel="stylesheet" type="text/css" href="images/styles.css"> </head> <body> <divalign="center"> <divclass="div1"> <divclass="top">提示信息</div> <divclass="bottom"> <divclass="div2"> <ul> <li><a href="reg.jsp">用户注册</a></li> <li><a href="login.jsp">用户登录</a></li> <li><a href="message.jsp">当前用户</a></li> <li><a href="UserExitServlet">用户退出</a></li> </ul> </div> <divclass="div3"> <% // 获取提示信息 String info = (String)request.getAttribute("info"); // 如果提示信息不为空，则输出提示信息 if(info != null){ out.println(info); } // 获取登录的用户信息 User user = (User)session.getAttribute("user"); // 判断用户是否登录 if(user != null){ %> <tablealign="center" width="350" border="1" height="200" bordercolor="#E8F4CC"> <tr> <tdalign="center" colspan="2"> <spanstyle="font-weight: bold;font-size: 18px;"><%=user.getUsername() %></span> 登录成功！ </td> </tr> <tr> <tdalign="right" width="30%">头 像：</td> <td> <imgsrc="<%=user.getPhoto()%>"> </td> </tr> <tr> <tdalign="right">性 别：</td> <td><%=user.getSex()%></td> </tr> <tr> <tdalign="right">联系电话：</td> <td><%=user.getTel()%></td> </tr> <tr> <tdalign="right">电子邮箱：</td> <td><%=user.getEmail()%></td> </tr> </table> <% }else{ out.println("<br>对不起，您还没有登录！"); } %> </div> </div> </div> </div> </body> </html>
5、Servlet配置
web.xml
<?xmlversion="1.0" encoding="UTF-8"?> <web-appversion="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"> <!-- 用户注册 --> <servlet> <servlet-name>RegServlet</servlet-name> <servlet-class>com.wuyudong.service.RegServlet</servlet-class> </servlet> <!-- 用户登录 --> <servlet> <servlet-name>LoginServlet</servlet-name> <servlet-class>com.wuyudong.service.LoginServlet</servlet-class> </servlet> <!-- 用户退出 --> <servlet> <servlet-name>UserExitServlet</servlet-name> <servlet-class>com.wuyudong.service.UserExitServlet</servlet-class> </servlet> <!-- Servlet映射 --> <servlet-mapping> <servlet-name>RegServlet</servlet-name> <url-pattern>/RegServlet</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/LoginServlet</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>UserExitServlet</servlet-name> <url-pattern>/UserExitServlet</url-pattern> </servlet-mapping> <!-- 过滤器 --> <filter> <filter-name>CharacterEncodingFilter</filter-name> <filter-class>com.wuyudong.util.CharacterEncodingFilter</filter-class> <init-param> <param-name>encoding</param-name> <param-value>GBK</param-value> </init-param> </filter> <filter-mapping> <filter-name>CharacterEncodingFilter</filter-name> <url-pattern>/*</url-pattern> <dispatcher>REQUEST</dispatcher> <dispatcher>FORWARD</dispatcher> </filter-mapping> <!-- 主页 --> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app>
6、字符编码过滤器
CharacterEncodingFilter.java
package com.wuyudong.util; import java.io.IOException; import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; /** * 字符编码过滤器 */ public class CharacterEncodingFilter implements Filter{ protected String encoding = null; protected FilterConfigfilterConfig = null; public void init(FilterConfigfilterConfig) throws ServletException { this.filterConfig = filterConfig; this.encoding = filterConfig.getInitParameter("encoding"); } public void doFilter(ServletRequestrequest, ServletResponseresponse, FilterChainchain) throws IOException, ServletException { if (encoding != null) { request.setCharacterEncoding(encoding); response.setContentType("text/html; charset="+encoding); } chain.doFilter(request, response); } public void destroy() { this.encoding = null; this.filterConfig = null; } }
最后运行的界面截图如下：
作者：工学1号馆