JavaBean实现用户登陆

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. 系统结构图

　　2.数据库表

create table P_USER
(
  id       VARCHAR2(50) not null,
  username VARCHAR2(20),
password VARCHAR2(20),
  email    VARCHAR2(50)
)

　　3.JavaBean编写

DataAccess.java   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

package data;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class DataAccess {
      private String driver="oracle.jdbc.driver.OracleDriver";
      private String url="jdbc:oracle:" + "thin:@localhost:1521:orcl";
      private String username="C##LYJ";
      private String password="lyj123123";
      private Connection con;
      private Statement stm=null;
      private ResultSet rs;
      
      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 steUsername(String username){
          this.username=username;
      }
      
      public String getPassword(){
          return password;
      }
      public void setPassword(String password){
          this.password=password;
      }
      
      public Connection getCon(){
          return con;
      }
      public void steCon(Connection con){
          this.con=con;
      }
      
      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;
      }
      //创建连接
      public boolean creatCon(){
          boolean b=false;
          try{
              Class.forName(driver);//加载oracle驱动程序
              con=DriverManager.getConnection(url, username, password);
              b=true;
          }catch(SQLException e){
              e.printStackTrace();
          }
          catch(ClassNotFoundException e){
              e.printStackTrace();
          }
          return b;
      }
      //修改
      public boolean update(String sql){
          boolean b=false;
          try{
              stm=this.con.createStatement();
              stm.execute(sql);
              b=true;
          }catch(SQLException e){
              e.printStackTrace();
          }
              return b;                        
      }
      //查询
      public void query(String sql){
          try{
              stm=con.createStatement();
              rs=stm.executeQuery(sql);
          }
          catch(SQLException e){
              e.getSQLState();
          }
      }
      
      //判断有无数据
      public boolean next(){
          boolean b=false;
          try{
              if(rs.next()){
                  b=true;
              }
          }catch(SQLException e){
              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){
              e.printStackTrace();
          }
          return value;
      }
      
      //关闭连接
      public void closeCon(){
          try{
              if(con!=null){
                  con.close();
              }
          }catch(SQLException e){
              e.printStackTrace();
          }
      }
      
      //关闭Statement
      public void closeStm(){
          try{
              if(stm!=null){
                  stm.close();
              }
          }catch(SQLException e){
              e.printStackTrace();
          }
      }
      
      //关闭ResultSet
      public void closeRs(){
          try{
              if(rs!=null){
                  rs.close();
              }
          }catch(SQLException e){
              e.printStackTrace();
          }
      }
      
}

UserBean.java   对数据库的增加、查询，即定义了登录验证、注册验证和新增用户等方法

package data;

public class UserBean {
    //登陆验证
    public boolean valid(String username,String password){
        boolean isValid=false;
        DataAccess db=new DataAccess();
        if(db.creatCon()){
            String sql="select * from p_user where us='"+username+"' and ps='"+password+"'";
            db.query(sql);
            if(db.next()){
                isValid=true;
                System.out.print("成功！");
            }
            db.closeRs();
            db.closeStm();
            db.closeCon();
        }
        return isValid;
    }
    
    //注册验证
    public boolean isExist(String username){
        boolean isValid=false;
        DataAccess db=new DataAccess();
        if(db.creatCon()){
            String sql="select * from p_user where us='"+username+"'";  
            db.query(sql);
            if(db.next()){
                isValid=true;
            }
            db.closeRs();
            db.closeStm();
            db.closeCon();
        }
        return isValid;
    }
    //注册用户
    public boolean add(String username,String password,String email){
        boolean isValid=false;
        DataAccess db=new DataAccess();
        if(db.creatCon()){
            String sql= "insert into p_user(id,us,ps,email) values('"+GenerateUnID.next()+"','"+username+"','"+password+"','"+email+"')";  
            isValid=db.update(sql);
            db.closeRs();
            db.closeStm();
            db.closeCon();
        }
        return isValid;
    }
}

 

GenerateUnID.java  为每个用户生成唯一ID

package data;
import java.util.Date;

public class GenerateUnID {
      private static Date date=new Date();
      private static int seq=0;
      private static final int ROTATION=99999;
      public static synchronized long next(){
          if(seq>ROTATION) seq=0;
          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.JSP页面编写

　　　　4.1 登陆页面  login.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 'index.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>
     <form action="login_action.jsp" method="post">
           <table>
               <tr>
                   <td colspan="2">登陆窗口</td>
               </tr>
               <tr>
                   <td>用户名：</td>
                   <td><input type="text" name="username"/></td>
               </tr>
               <tr>
                   <td>密    码：</td>
                   <td><input type="password" name="password"/></td>
               </tr>
               <tr>
                   <td colspan="2"><input type="submit" value="登陆"/><a href="register.jsp">注册</a></td>
               </tr>
           </table>
   </form>
  </body>
</html>

　　　　4.2 登陆页面逻辑处理  login_action.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 'login_action.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>
    <%@ page import="data.*" %>
    <%@ page import="java.sql.*" %>
  
   <%
           String us=request.getParameter("username");
           String ps=request.getParameter("password");
           if(us==null||"".equals(us.trim())||ps==null||"".equals(ps.trim())){
               System.out.print("用户名或者密码不能为空!");
               response.sendRedirect("index.jsp");
               
           }
         
           UserBean userBean=new UserBean();
           boolean isValid=userBean.valid(us, ps);
           System.out.print(isValid);
           if(isValid){
               System.out.println("登陆成功！");
               session.setAttribute("username", us);
               response.sendRedirect("welcom.jsp");
           }
           else{
               System.out.print("用户名或者密码错误！");
               response.sendRedirect("login.jsp");
           }
           
    %>
  </body>
</html>

　　　　4.3　登陆欢迎界面 welcom.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>
    <form action="loginout.jsp" method="post">
        <table>
            <tr>
                <td colspan="2">登陆成功</td>
            </tr>
            <tr>
                <td>欢迎你：</td>
                <td><%=session.getAttribute("username")%></td>
            </tr>
            <tr>
                <td colspan="2"><input type="submit" value="退出"/></td>
            </tr>
        </table>
    </form>
  </body>
</html>

　　　　4.4  用户注册页面 register.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 'register.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>
    <form action="register_action.jsp" method="post">
        <table>
            <tr>
                <td colspan="2">窗口注册</td>
            </tr>
            <tr>
                <td>用户名：</td>
                <td><input type="text" name="username"></td>
            </tr>
            <tr>
                <td>密       码：</td>
                <td><input type="password" name="password1"></td>
            </tr>
            <tr>
                <td>确认密码：</td>
                <td><input type="password" 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>

　　　　4.4 注册页面逻辑处理 register_action.jsp

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<%@ page import="data.*" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'register_action.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>
      
      <%
          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)||password2==null||"".equals(password2)||!password1.equals(password2)){
              System.out.print("用户名或密码不能为空！");
              response.sendRedirect("register.jsp");
              return;
          }
          UserBean userbean=new UserBean();
          boolean isExit=userbean.isExist(username);
          if(!isExit){
              userbean.add(username, password1, email);
              System.out.print("注册成功，请登陆！");
              response.sendRedirect("login.jsp");
              
          }
          else{
              System.out.print("用户名已存在！");
              response.sendRedirect("register.jsp");
              
          }
       %>
  </body>
</html>

　　　　4.5  退出页面

<%@ 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>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>

　　　　5. 总结

　　　　　　主要是为了使用javabean对数据库操作和业务逻辑处理进行了封装，例子很简单，由小及大，掌握思想即可。

源码：https://github.com/lyj8330328/JavaBean