Java組件javabean用戶登錄實例詳解

本文簡單講述使用javabean實現用戶登錄，包括用戶登錄，註冊和退出等。

1.關於javabean
JavaBean 是一種JAVA語言寫成的可重用組件。為寫成JavaBean，類必須是具體的和公共的，並且具有無參數的構造器。 JavaBean 通過提供符合一致性設計模式的公共方法將內部域暴露成員屬性，set和get方法獲取。眾所周知，屬性名稱符合這種模式，其他Java 類可以通過自省機制發現和操作這些JavaBean 的屬性。

2.系統架構
2.1登錄用例圖

2.2頁面流程圖

2.3系統架構圖

2.4數據庫設計
本例使用oracle數據庫

用戶表包括id，用戶名，密碼，email，共4個字段

-- 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 '用戶表'; -- Add comments to the columns comment on column P_USER.id is 'id'; comment on column P_USER.username is '用戶名'; comment on column P_USER.password is '密碼'; comment on column P_USER.email is 'email';

3.javabean編寫
3.1開發數據庫底層處理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; /**數據庫操作類* <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; //創建連接public boolean createConn() { boolean b = false; try { Class.forName(driver);// 加載Oracle驅動程序conn = DriverManager.getConnection(url, username, password); b = true; } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); }// 獲取連接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; } //查詢public void query(String sql){ try { stm = conn.createStatement(); rs = stm.executeQuery(sql); } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } //判斷有無數據public boolean next(){ boolean b = false; try { if(rs.next()){ b = true; } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } return b; } //獲取表字段值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; } //關閉連接public void closeConn() { try { if (conn != null) { conn.close(); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } //關閉statement public void closeStm() { try { if (stm != null) { stm.close(); } } catch (SQLException e) { // TODO Auto-generated catch block e.printStackTrace(); } } //關閉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; } }

上述數據庫操作類使用JDBC連接數據庫，並封裝了連接數據庫、查詢、修改、關閉資源等方法。

3.2開發JavaBean業務邏輯組件
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 { //登錄驗證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; } //註冊驗證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; } //註冊用戶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; } }

上述業務邏輯javabean，定義了登錄驗證、註冊驗證和新增用戶等方法

3.3關於生成唯一ID
上面在新增用戶時需要插入ID，本例使用UUID來生成唯一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.頁面編寫
4.1登錄頁面
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>登錄頁面</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">登錄窗口</td> </tr> <tr> <td>用戶名：</td> <td><input type="text" name="username" /> </td> </tr> <tr> <td>密碼：</td> <td><input type="text" name="password" /> </td> </tr> <tr> <td colspan="2"><input type="submit" value="登錄" /> <a href="register.jsp">註冊</a> </td> </tr> </table> </form> </body> </html>

頁面效果

4.2登錄業務邏輯處理頁面
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("用戶名或密碼不能為空！"); System.out.println("用戶名或密碼不能為空！"); 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("登錄成功！"); session.setAttribute("username", username); response.sendRedirect("welcome.jsp"); return; }else{ System.out.println("用戶名或密碼錯誤，登錄失敗！"); response.sendRedirect("login.jsp"); return; } %>

上面的JSP調用了Javabean進行業務處理當用戶名或密碼為空時返回登錄頁面login.jsp

當登錄成功後將用戶信息保存到session，跳轉到歡迎頁面welcome.jsp

當登錄失敗時返回登錄頁面login.jsp

4.3登錄成功歡迎頁面
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" /> </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">登錄成功!</td> </tr> <tr> <td>歡迎你，</td> <td>${username }</td> </tr> <tr> <td colspan="2"><input type="submit" value="退出" /></td> </tr> </table> </form></td> </tr> </table> </body> </html>

頁面效果

4.4退出登錄業務處理頁面
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>

從session中移除用戶信息，跳轉到登錄頁面login.jsp

4.5用戶註冊頁面
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>註冊頁面</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">註冊窗口</td> </tr> <tr> <td>用戶名：</td> <td><input type="text" name="username" /></td> </tr> <tr> <td>密碼：</td> <td><input type="text" name="password1" /></td> </tr> <tr> <td>確認密碼：</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="註冊" /> <a href="login.jsp">返回</a></td> </tr> </table> </form> </body> </html>

運行效果

4.6註冊業務處理頁面

<%@ 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("用戶名或密碼不能為空！"); System.out.println("用戶名或密碼不能為空！"); 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("註冊成功，請登錄！ "); response.sendRedirect("login.jsp"); return; }else{ System.out.println("用戶名已存在！"); response.sendRedirect("register.jsp"); return; } %>

上面的JSP調用了Javabean進行業務處理

當用戶名或密碼為空時返回註冊頁面register.jsp

當註冊用戶名在數據庫不存在時，新增用戶

新增成功後跳轉到登錄頁面login.jsp

當註冊用戶名在數據庫存在時，返回註冊頁面register.jsp

5.總結

本例使用javabean對數據庫操作和業務邏輯處理進行了封裝。

以上即為使用javabean實現用戶登錄的簡單介紹，還需要不斷完善，希望大家一起學習進步！