DAO模式就实现了把数据库表的操作转化对Java类的操作，从而提高程序的可读性，并实现更改数据库的方便性。其架构图如下图。
一共分为五个组件(component)
jsp提交页面（一下四其中的一个例子，HTML的例子）
1 <%@ page language="java" contentType="text/html; charset=UTF-8" 2 pageEncoding="UTF-8"%> 3 <html> 4 <head> <title>添加信息提交页面</title> 5 <style type="text/css"> 6 body{ 7 background-image:url(src.img/6.jpg); /*图片地址*/ 8 background-origin:content; /*从content区域开始显示背景*/ 9 background-position:50% 5%; /* 图片上下左右居中 */ 10 background-size:cover; /* 保持图像本身的宽高比例，将图片缩放到宽度或高度正好适应定义背景的区域 */ 11 background-repeat:no-repeat; /* 图像不重复显示 */ 12 } 13 td{font-size: 12px;} 14 h2{margin: 0px} 15 table { 16 background-color: rgba(255, 255, 255, 0.9); 17 margin-top:200px; 18 margin-left: center; 19 height: 50px; 20 width: 300px; 21 border-radius: 6px; 22 } 23 td.{ 24 text-align: center; 25 align: center; 26 font-family: 微软雅黑; 27 font-size: 20px; 28 } 29 input.submit { 30 align:center; 31 background:#0080ff; 32 width: 100px; 33 font-size: 25px; 34 font-family:微软雅黑; 35 color: #ffffff; 36 border:1px; 37 border-radius: 6px; 38 } 39 </style> 40 </head> 41 <body> 42 <form action="jsreg" method="post"> 43 <table border="0" width="238" height="252"> 44 <tr><td>教师</td><td><input type="text" name="username"></td></tr> 45 <tr><td>密码</td><td><input type="text" name="ps"></td></tr> 46 <tr align="center"> 47 <td colspan="2"> 48 <input type="submit" value="登录"> 49 </td> 50 <td> 51 <a href="updateteacher.jsp" >忘记密码？</a> 52 </td> 53 </tr> 54 </table> 55 </form> 56 </body> 57 </html>
Struts.xml的配置（Congfiguration）文件
</action> <action name="jsreg" class="Action.ther"> <result name="success">/index_student_left.jsp</result> </action>
JavaBean如下
public class Teacher { private String username; private String ps; public String getUsername() { return username; } public void setUsername(String username) { this.username = username; } public String getPs() { return ps; } public void setPs(String ps) { this.ps = ps; } }
接口类型如下
import domain.Teacher; public interface Iteacher { public abstract Teacher find (Teacher te) throws Exception; }
DAO如下
package dao; import java.sql.*; import db.DbConnect; import domain.Teacher; public class TeacherDAO implements Iteacher{ protected static final String FIELDS_INSERT="username,ps"; protected static String SELECT_SQL="select "+FIELDS_INSERT+" from Teacher where username=?"; protected static String UPDATE_SQL="update Teacher set "+"username=?,ps=? where username=?"; public Teacher find(Teacher te) throws Exception { Connection con=null; PreparedStatement prepStmt=null; ResultSet rs=null; Teacher te2=null; try{ con=DbConnect.getDBconnection(); prepStmt=con.prepareStatement(SELECT_SQL); prepStmt.setString(1, te.getUsername()); rs=prepStmt.executeQuery(); if(rs.next()){ te2=new Teacher(); te2.setUsername(rs.getString(1)); te2.setPs(rs.getString(2)); } }catch(Exception e){ }finally{ DbConnect.closeDB(con, prepStmt, rs); } return te2; }
连接数据库的Dbconnect
package db; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; public class DbConnect { private static String driverName="com.microsoft.sqlserver.jdbc.SQLServerDriver"; private static String userName="sa"; private static String userpwd="13481195624q"; private static String dbName="Student"; public static Connection getDBconnection() { String dbURL="jdbc:sqlserver://localhost:1433;DatabaseName=Student"; try { Class.forName(driverName); Connection con=DriverManager.getConnection(dbURL,userName,userpwd); return con; }catch(Exception e) { e.printStackTrace(); } return null; } public static void closeDB(Connection con, PreparedStatement pstm, ResultSet rs) { try { if(rs!=null)rs.close(); if(pstm!=null)pstm.close(); if(con!=null)con.close(); }catch(SQLException e){ e.printStackTrace(); } } }
执行Action页面
package Action; import dao.TeacherDAO; import domain.Teacher; import java.util.Map; import java.util.regex.*; import com.opensymphony.xwork2.ActionContext; import com.opensymphony.xwork2.ActionSupport; import javax.servlet.http.HttpServletRequest; import org.apache.struts2.ServletActionContext; public class ther extends ActionSupport{ private HttpServletRequest request; public String execute() throws Exception { request=ServletActionContext.getRequest(); Teacher te=new Teacher(); te.setUsername(request.getParameter("username")); te.setPs(request.getParameter("ps")); TeacherDAO te2=new TeacherDAO(); try { te=te2.find(te); request.setAttribute("teacher", te); } catch (Exception e) { e.printStackTrace(); } return "success"; } }
显示的JSP页面
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@page import="java.util.List"%> <%@page import="domain.Teacher"%> <html> <head><title>所有学生信息</title> <style type="text/css"> body{ background-image:url(src.img/7.jpg); /*图片地址*/ background-origin:content; /*从content区域开始显示背景*/ background-position:50% 5%; /* 图片上下左右居中 */ background-size:cover; /* 保持图像本身的宽高比例，将图片缩放到宽度或高度正好适应定义背景的区域 */ background-repeat:no-repeat; /* 图像不重复显示 */ } td{font-size: 12px;} h2{margin: 0px} table { background-color: rgba(255, 255, 255, 0.9); margin-top:200px; margin-left: center; height: 50px; width: 300px; border-radius: 6px; } td.{ text-align: center; align: center; font-family: 微软雅黑; font-size: 20px; } </style> </head> <body> <table align="center" width="450" border="1" height="180" bordercolor="white" bgcolor="black" cellpadding="1" cellspacing="1"> <tr bgcolor="white"> <td align="center" colspan="5"> <h2>所有教师信息</h2> </td> </tr> <tr align="center" bgcolor="#e1ffc1"> <td><b>姓名</b></td> <td><b>密码</b></td> </tr> <%Teacher teacher=(Teacher)request.getAttribute("teacher");%> <tr align="center" bgcolor="white"> <td><%=teacher.getUsername()%></td> <td><%=teacher.getPs()%></td> </tr> </table> </body> </html>
教师信息如下
