Java组件javabean用户登录实例详解

Z时代
2024-01-10
分类：IT

本文简单讲述使用javabean实现用户登录，包括用户登录，注册和退出等。

1.关于javabean

JavaBean 是一种JAVA语言写成的可重用组件。为写成JavaBean，类必须是具体的和公共的，并且具有无参数的构造器。JavaBean 通过提供符合一致性设计模式的公共方法将内部域暴露成员属性，set和get方法获取。众所周知，属性名称符合这种模式，其他Java 类可以通过自省机制发现和操作这些JavaBean 的属性。

2.系统架构

2.1登录用例图

2.2页面流程图

2.3系统架构图

2.4数据库设计

本例使用oracle数据库

用户表包括id，用户名，密码，email，共4个字段


-- Create table 
create table P_USER 
( 
 id  VARCHAR2(50) not null, 
 username VARCHAR2(20), 
 password VARCHAR2(20), 
 email VARCHAR2(50) 
) 
tablespace USERS 
 pctfree 10 
 initrans 1 
 maxtrans 255 
 storage 
 ( 
 initial 64 
 minextents 1 
 maxextents unlimited 
 ); 
-- Add comments to the table 
comment on table P_USER 
 is '用户表'; 
-- Add comments to the columns 
comment on column P_USER.id 
 is 'id'; 
comment on column P_USER.username 
 is '用户名'; 
comment on column P_USER.password 
 is '密码'; 
comment on column P_USER.email 
 is 'email';

3.javabean编写

3.1开发数据库底层处理javabean

DBAcess.java


package com.baosight.bean; 
import java.sql.Connection; 
import java.sql.DriverManager; 
import java.sql.ResultSet; 
import java.sql.SQLException; 
import java.sql.Statement; 
/**数据库操作类 
 * <p>Title:DBAcess </p> 
 * <p>Description:TODO </p> 
 * <p>Company: </p> 
 * @author yuan 
 * @date 2016-5-22 下午12:40:24*/ 
public class DBAcess { 
 private String driver = "oracle.jdbc.driver.OracleDriver"; 
 private String url = "jdbc:oracle:" + "thin:@127.0.0.1:1521:orcl"; 
 private String username = "scott"; 
 private String password = "tiger"; 
 private Connection conn; 
 private Statement stm; 
 private ResultSet rs; 
 //创建连接 
 public boolean createConn() { 
  boolean b = false; 
  try { 
   Class.forName(driver);// 加载Oracle驱动程序 
   conn = DriverManager.getConnection(url, username, password); 
   b = true; 
  } catch (SQLException e) { 
   // TODO Auto-generated catch block 
   e.printStackTrace(); 
  }// 获取连接 
  catch (ClassNotFoundException e) { 
   // TODO Auto-generated catch block 
   e.printStackTrace(); 
  } 
  return b; 
 } 
 //修改 
 public boolean update(String sql){ 
  boolean b = false; 
  try { 
   stm = conn.createStatement(); 
   stm.execute(sql); 
   b = true; 
  } catch (SQLException e) { 
   // TODO Auto-generated catch block 
   e.printStackTrace(); 
  } 
  return b; 
 } 
 //查询 
 public void query(String sql){ 
  try { 
   stm = conn.createStatement(); 
   rs = stm.executeQuery(sql); 
  } catch (SQLException e) { 
   // TODO Auto-generated catch block 
   e.printStackTrace(); 
  } 
 } 
 //判断有无数据 
 public boolean next(){ 
  boolean b = false; 
  try { 
   if(rs.next()){ 
    b = true; 
   } 
  } catch (SQLException e) { 
   // TODO Auto-generated catch block 
   e.printStackTrace(); 
  } 
  return b; 
 } 
 //获取表字段值 
 public String getValue(String field) { 
  String value = null; 
  try { 
   if (rs != null) { 
    value = rs.getString(field); 
   } 
  } catch (SQLException e) { 
   // TODO Auto-generated catch block 
   e.printStackTrace(); 
  } 
  return value; 
 } 
 //关闭连接 
 public void closeConn() { 
  try { 
   if (conn != null) { 
    conn.close(); 
   } 
  } catch (SQLException e) { 
   // TODO Auto-generated catch block 
   e.printStackTrace(); 
  } 
 } 
 //关闭statement 
 public void closeStm() { 
  try { 
   if (stm != null) { 
    stm.close(); 
   } 
  } catch (SQLException e) { 
   // TODO Auto-generated catch block 
   e.printStackTrace(); 
  } 
 } 
 //关闭ResultSet 
 public void closeRs() { 
  try { 
   if (rs != null) { 
    rs.close(); 
   } 
  } catch (SQLException e) { 
   // TODO Auto-generated catch block 
   e.printStackTrace(); 
  } 
 } 
 public String getDriver() { 
  return driver; 
 } 
 public void setDriver(String driver) { 
  this.driver = driver; 
 } 
 public String getUrl() { 
  return url; 
 } 
 public void setUrl(String url) { 
  this.url = url; 
 } 
 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 Statement getStm() { 
  return stm; 
 } 
 public void setStm(Statement stm) { 
  this.stm = stm; 
 } 
 public ResultSet getRs() { 
  return rs; 
 } 
 public void setRs(ResultSet rs) { 
  this.rs = rs; 
 } 
 public void setConn(Connection conn) { 
  this.conn = conn; 
 } 
 public Connection getConn() { 
  return conn; 
 } 
}

上述数据库操作类使用JDBC连接数据库，并封装了连接数据库、查询、修改、关闭资源等方法。

3.2开发JavaBean业务逻辑组件

UserBean.java


package com.baosight.bean; 
import com.baosight.util.GenerateUUID; 
/** 
 * <p>Title:UserBean </p> 
 * <p>Description:TODO </p> 
 * <p>Company: </p> 
 * @author yuan 
 * @date 2016-5-22 下午1:05:00*/ 
public class UserBean { 
 //登录验证 
 public boolean valid(String username,String password){ 
  boolean isValid = false; 
  DBAcess db = new DBAcess(); 
  if(db.createConn()){ 
   String sql = "select * from p_user where username='"+username+"' and password='"+password+"'"; 
   db.query(sql); 
   if(db.next()){ 
    isValid = true; 
   } 
   db.closeRs(); 
   db.closeStm(); 
   db.closeConn(); 
  } 
  return isValid; 
 } 
 //注册验证 
 public boolean isExist(String username){ 
  boolean isValid = false; 
  DBAcess db = new DBAcess(); 
  if(db.createConn()){ 
   String sql = "select * from p_user where username='"+username+"'"; 
   db.query(sql); 
   if(db.next()){ 
    isValid = true; 
   } 
   db.closeRs(); 
   db.closeStm(); 
   db.closeConn(); 
  } 
  return isValid; 
 } 
 //注册用户 
 public boolean add(String username,String password,String email){ 
  boolean isValid = false; 
  DBAcess db = new DBAcess(); 
  if(db.createConn()){ 
   String sql = "insert into p_user(id,username,password,email) values('"+GenerateUUID.next()+"','"+username+"','"+password+"','"+email+"')"; 
   isValid = db.update(sql); 
   db.closeStm(); 
   db.closeConn(); 
  } 
  return isValid; 
 } 
}

上述业务逻辑javabean，定义了登录验证、注册验证和新增用户等方法

3.3关于生成唯一ID

上面在新增用户时需要插入ID，本例使用UUID来生成唯一ID

GenerateUUID.java


package com.baosight.util; 
import java.util.Date; 
/** 
 * <p>Title:GenerateUUID </p> 
 * <p>Description:TODO </p> 
 * <p>Company: </p> 
 * @author yuan 
 * @date 2016-5-22 下午1:31:46*/ 
public class GenerateUUID { 
  private static Date date = new Date(); 
// private static StringBuilder buf = new StringBuilder(); 
  private static int seq = 0; 
  private static final int ROTATION = 99999; 
  public static synchronized long next(){ 
  if (seq > ROTATION) seq = 0; 
//  buf.delete(0, buf.length()); 
  date.setTime(System.currentTimeMillis()); 
  String str = String.format("%1$tY%1$tm%1$td%1$tk%1$tM%1$tS%2$05d", date, seq++); 
  return Long.parseLong(str); 
 } 
  public static void main(String[] args) { 
   for(int i=0;i<100;i++){ 
    System.out.println(next()); 
   } 
 } 
}

4.页面编写

4.1登录页面


<%@ 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>登录页面</title> 
 <meta http-equiv="pragma" content="no-cache"> 
 <meta http-equiv="cache-control" content="no-cache"> 
 <meta http-equiv="expires" content="0">  
 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> 
 <meta http-equiv="description" content="This is my page"> 
 <!-- 
 <link rel="stylesheet" type="text/css" href="styles.css"> 
 --> 
 </head> 
 <body> 
 <form action="login_action.jsp" method="post"> 
  <table> 
   <tr> 
    <td colspan="2">登录窗口</td> 
   </tr> 
   <tr> 
    <td>用户名：</td> 
    <td><input type="text" name="username" /> 
    </td> 
   </tr> 
   <tr> 
    <td>密码：</td> 
    <td><input type="text" name="password" /> 
    </td> 
   </tr> 
   <tr> 
    <td colspan="2"><input type="submit" value="登录" /> <a href="register.jsp">注册</a> 
    </td> 
   </tr> 
  </table> 
 </form> 
</body> 
</html>

页面效果

4.2登录业务逻辑处理页面

login_action.jsp


<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> 
<%@ page import="java.sql.*" %> 
<%@ page import="com.baosight.bean.*" %> 
<% 
String path = request.getContextPath(); 
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 
%> 
 <% 
 String username = request.getParameter("username"); 
 String password = request.getParameter("password"); 
 if(username==null||"".equals(username.trim())||password==null||"".equals(password.trim())){ 
  //out.write("用户名或密码不能为空！"); 
  System.out.println("用户名或密码不能为空！"); 
  response.sendRedirect("login.jsp"); 
  return; 
  //request.getRequestDispatcher("login.jsp").forward(request, response); 
 } 
 UserBean userBean = new UserBean(); 
 boolean isValid = userBean.valid(username,password); 
 if(isValid){ 
  System.out.println("登录成功！"); 
  session.setAttribute("username", username); 
  response.sendRedirect("welcome.jsp"); 
  return; 
 }else{ 
  System.out.println("用户名或密码错误，登录失败！"); 
  response.sendRedirect("login.jsp"); 
  return; 
 } 
 %>

上面的JSP调用了Javabean进行业务处理

当用户名或密码为空时返回登录页面login.jsp

当登录成功后将用户信息保存到session，跳转到欢迎页面welcome.jsp

当登录失败时返回登录页面login.jsp

4.3登录成功欢迎页面

welcome.jsp


<%@ 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 'welcom.jsp' starting page</title> 
 <meta http-equiv="pragma" content="no-cache"> 
 <meta http-equiv="cache-control" content="no-cache"> 
 <meta http-equiv="expires" content="0">  
 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> 
 <meta http-equiv="description" content="This is my page"> 
 <!-- 
 <link rel="stylesheet" type="text/css" href="styles.css"> 
 --> 
 </head> 
 <body> 
 <table> 
  <tr> 
   <td><img src="images/logo4.png" /> 
   </td> 
   <td><img src="images/logo2.png" height="90" /> 
   </td> 
  </tr> 
  <tr> 
   <td colspan="2"><hr /> 
   </td> 
  </tr> 
  <tr> 
   <td> 
    <table> 
     <tr> 
      <td><a>Main</a> 
      </td> 
     </tr> 
     <tr> 
      <td><a>Menu1</a> 
      </td> 
     </tr> 
     <tr> 
      <td><a>Menu2</a> 
      </td> 
     </tr> 
     <tr> 
      <td><a>Menu3</a> 
      </td> 
     </tr> 
     <tr> 
      <td><a>Menu4</a> 
      </td> 
     </tr> 
     <tr> 
      <td><a>Menu5</a> 
      </td> 
     </tr> 
     <tr> 
      <td><a>Menu6</a> 
      </td> 
     </tr> 
     <tr> 
      <td><a>Menu7</a> 
      </td> 
     </tr> 
     <tr> 
      <td><a>Menu8</a> 
      </td> 
     </tr> 
    </table></td> 
   <td> 
    <form action="loginout.jsp" method="post"> 
     <table> 
      <tr> 
       <td colspan="2">登录成功!</td> 
      </tr> 
      <tr> 
       <td>欢迎你，</td> 
       <td>${username }</td> 
      </tr> 
      <tr> 
       <td colspan="2"><input type="submit" value="退出" /></td> 
      </tr> 
     </table> 
    </form></td> 
  </tr> 
 </table> 
</body> 
</html>

页面效果

4.4退出登录业务处理页面

loginout.jsp


<%@ 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 'loginout.jsp' starting page</title> 
 <meta http-equiv="pragma" content="no-cache"> 
 <meta http-equiv="cache-control" content="no-cache"> 
 <meta http-equiv="expires" content="0">  
 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> 
 <meta http-equiv="description" content="This is my page"> 
 <!-- 
 <link rel="stylesheet" type="text/css" href="styles.css"> 
 --> 
 </head> 
 <body> 
 <% 
 session.removeAttribute("username"); 
 response.sendRedirect("login.jsp"); 
 %> 
 </body> 
</html>

从session中移除用户信息，跳转到登录页面login.jsp

4.5用户注册页面


<%@ 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>注册页面</title> 
 <meta http-equiv="pragma" content="no-cache"> 
 <meta http-equiv="cache-control" content="no-cache"> 
 <meta http-equiv="expires" content="0">  
 <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> 
 <meta http-equiv="description" content="This is my page"> 
 <!-- 
 <link rel="stylesheet" type="text/css" href="styles.css"> 
 --> 
 </head> 
 <body> 
 <form action="register_action.jsp" method="post"> 
  <table> 
   <tr> 
    <td colspan="2">注册窗口</td> 
   </tr> 
   <tr> 
    <td>用户名：</td> 
    <td><input type="text" name="username" /></td> 
   </tr> 
   <tr> 
    <td>密码：</td> 
    <td><input type="text" name="password1" /></td> 
   </tr> 
   <tr> 
    <td>确认密码：</td> 
    <td><input type="text" name="password2" /></td> 
   </tr> 
   <tr> 
    <td>email：</td> 
    <td><input type="text" name="email" /></td> 
   </tr> 
   <tr> 
    <td colspan="2"><input type="submit" value="注册" /> <a href="login.jsp">返回</a></td> 
   </tr> 
  </table> 
 </form> 
</body> 
</html>

运行效果

4.6注册业务处理页面


<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> 
<%@ page import="java.sql.*" %> 
<%@ page import="com.baosight.bean.*" %> 
<% 
String path = request.getContextPath(); 
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; 
%> 
 <% 
 String username = request.getParameter("username"); 
 String password1 = request.getParameter("password1"); 
 String password2 = request.getParameter("password2"); 
 String email = request.getParameter("email"); 
 if(username==null||"".equals(username.trim())||password1==null||"".equals(password1.trim())||password2==null||"".equals(password2.trim())||!password1.equals(password2)){ 
  //out.write("用户名或密码不能为空！"); 
  System.out.println("用户名或密码不能为空！"); 
  response.sendRedirect("register.jsp"); 
  return; 
  //request.getRequestDispatcher("login.jsp").forward(request, response); 
 } 
 UserBean userBean = new UserBean(); 
 boolean isExit = userBean.isExist(username); 
 if(!isExit){ 
  userBean.add(username, password1, email); 
  System.out.println("注册成功，请登录！"); 
  response.sendRedirect("login.jsp"); 
  return; 
 }else{ 
  System.out.println("用户名已存在！"); 
  response.sendRedirect("register.jsp"); 
  return; 
 } 
 %>