在DAO设计模式中使用工厂设计
工厂设计：
使用工厂设计，使前台不用知道具体子类是谁，是前台显示与后台逻辑操作分离，便于修改。
实例：在DAO设计模式中加入工厂设计
DAOFactory.java:使用工厂设计设置子类
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package mgc.dao.factory;
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import mgc.dao.test.*;
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import mgc.dao.test.impl.*;
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public class DAOFactory {
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public static MemberDAO getMemberDAOInstance() {
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return new MemberDAOImpl();
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}
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}
MemberDAO.java:数据库操作接口类
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package mgc.dao.test;
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import java.util.*;
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import mgc.dao.vo.*;
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//规定操作member表的全部方法
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public interface MemberDAO {
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//插入数据
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public void insert(Member member) throws Exception;
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//修改数据
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public void update(Member member) throws Exception;
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//删除数据
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public void delete( int id) throws Exception;
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//按ID查询
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public Member queryById( int id) throws Exception;
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//全部查询
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public List queryAll() throws Exception;
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}
Member.java:VO对象类
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package mgc.dao.vo;
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public class Member {
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private int id;
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private String username;
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private String password;
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public void setId( int id){
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this .id=id;
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}
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public void setUsername(String username){
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this .username=username;
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}
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public void setPassword(String password){
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this .password=password;
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}
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public int getId(){
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return this .id;
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}
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public String getUsername(){
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return this .username;
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}
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public String getPassword(){
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return this .password;
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}
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}
DatabaseConnection.java:数据库连接类
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package mgc.dao.test.dbc;
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import java.sql.*;
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public class DataBaseConnection {
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private final String DBDRIVER= "sun.jdbc.odbc.JdbcOdbcDriver" ;
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private final String DBURL= "jdbc:odbc:member" ;
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private Connection conn= null ;
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public DataBaseConnection() {
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try {
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Class.forName(DBDRIVER);
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this .conn=DriverManager.getConnection(DBURL);
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}
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catch (Exception e){}
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}
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public Connection getConnection() {
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return this .conn;
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}
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public void close() {
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try {
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this .conn.close();
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}
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catch (Exception e){}
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}
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}
MemberDAOImpl.java:数据库操作类
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package mgc.dao.test.impl;
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import java.util.*;
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import java.sql.*;
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import mgc.dao.vo.*;
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import mgc.dao.test.*;
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import mgc.dao.test.dbc.*;
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public class MemberDAOImpl implements MemberDAO {
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//插入数据
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public void insert(Member member) throws Exception {
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String sql= "Insert INTO member (username,password) VALUES (?,?)" ;
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PreparedStatement pstmt= null ;
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DataBaseConnection dbc= null ;
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try {
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//连接数据库
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dbc= new DataBaseConnection();
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pstmt=dbc.getConnection().prepareStatement(sql);
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pstmt.setString( 1 , member.getUsername());
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pstmt.setString( 2 , member.getPassword());
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//操作数据库
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pstmt.executeUpdate();
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pstmt.close();
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}
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catch (Exception e) {
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throw new Exception(e);
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}
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finally {
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//关闭数据库
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dbc.close();
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}
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}
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//修改操作
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public void update(Member member) throws Exception {
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String sql= "Update member SET username=?,password=? Where ID=?" ;
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PreparedStatement pstmt= null ;
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DataBaseConnection dbc= null ;
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try {
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//连接数据库
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dbc= new DataBaseConnection();
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pstmt=dbc.getConnection().prepareStatement(sql);
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pstmt.setString( 1 , member.getUsername());
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pstmt.setString( 2 , member.getPassword());
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pstmt.setInt( 3 ,member.getId());
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//操作数据库
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pstmt.executeUpdate();
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pstmt.close();
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}
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catch (Exception e) {
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throw new Exception(e);
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}
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finally {
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//关闭数据库
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dbc.close();
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}
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}
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public void delete( int id) throws Exception {
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String sql= "Delete FROM member Where ID=?" ;
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PreparedStatement pstmt= null ;
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DataBaseConnection dbc= null ;
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try {
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//连接数据库
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dbc= new DataBaseConnection();
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pstmt=dbc.getConnection().prepareStatement(sql);
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pstmt.setInt( 1 , id);
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//操作数据库
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pstmt.executeUpdate();
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pstmt.close();
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}
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catch (Exception e) {
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throw new Exception(e);
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}
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finally {
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//关闭数据库
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dbc.close();
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}
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}
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public Member queryById( int id) throws Exception {
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String sql= "Select * FROM member Where ID=?" ;
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PreparedStatement pstmt= null ;
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DataBaseConnection dbc= null ;
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ResultSet rs= null ;
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Member member= null ;
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try {
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//连接数据库
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dbc= new DataBaseConnection();
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pstmt=dbc.getConnection().prepareStatement(sql);
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pstmt.setInt( 1 , id);
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//操作数据库
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rs=pstmt.executeQuery();
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if (rs.next()) {
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//将查询结果保存在Member对象中
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member= new Member();
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member.setUsername(rs.getString( "username" ));
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member.setPassword(rs.getString( "password" ));
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}
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rs.close();
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pstmt.close();
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}
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catch (Exception e) {
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throw new Exception(e);
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}
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finally {
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//关闭数据库
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dbc.close();
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}
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return member;
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}
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public List queryAll() throws Exception {
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String sql= "Select * FROM member" ;
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PreparedStatement pstmt= null ;
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DataBaseConnection dbc= null ;
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ResultSet rs= null ;
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List all= new ArrayList();
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try {
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//连接数据库
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dbc= new DataBaseConnection();
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pstmt=dbc.getConnection().prepareStatement(sql);
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//操作数据库
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rs=pstmt.executeQuery();
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while (rs.next()) {
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//将查询结果保存在Member对象中
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Member member= new Member();
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member.setUsername(rs.getString( "username" ));
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member.setPassword(rs.getString( "password" ));
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all.add(member);
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}
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rs.close();
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pstmt.close();
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}
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catch (Exception e) {
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throw new Exception(e);
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}
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finally {
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//关闭数据库
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dbc.close();
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}
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return all;
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}
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}
dao.jsp:前台显示页面
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<%@page contentType="text/html;charset=GB2312" %>
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<%@page import="java.util.*" %>
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<%@page import="mgc.dao.factory.*" %>
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<%@page import="mgc.dao.test.impl.*" %>
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<%@page import="mgc.dao.vo.*" %>
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< html >
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< head >
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< title >dao.jsp</ title ></c
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gstarwd
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