基于jsp的bbs论坛-(4)java中对dao的实现

DAO层一般有接口和该接口的实现类！ 接口用于规范实现类！ 实现类一般用于用于操作数据库！ 一般操作修改，添加，删除数据库操作的步骤很相似，就写了一个公共类DAO类 ，修改，添加，删除数据库操作时 直接调用公共类DAO类！

一、对com.itqinxun.dao包的实现

该包下有3个Java文件，分别定义了对上述包中所定义3个对象类与数据库的相关操作，也即定义了相关的功能，但只是定义，并未进行具体实现

1.1、在包下创建AccountDao.java文件

内容为：

package com.itqinxun.dao;import com.itqinxun.model.Account;import java.util.List;public interface AccountDao {    public   boolean   addAccount(Account account);//新增账号信息    public   boolean   deleteAccount(Account account);//删除账号信息,将用户权限设为2，即不可登陆    public   boolean   updateAccount(Account account);//更新账号信息    public   List<Account>   searchAccountAll();//显示所有账号信息,只查询普通童虎    public   List<Account>   searchAdminAll();//只查询管理员    public   Account   returnAccountByaccount_account(Account account);  //根据用户数字账号返回用户    public   Account   loginAccount(Account account); //查询登录信息以及返回用户    public   Account   adminloginAccount(Account account);//查询管理用户信息以及返回用户    public   boolean   setAccountAdmin(Account account);//将用户权限变为1，即使管理员}

1.2、在包下创建MessageDao.java文件

内容为：

package com.itqinxun.dao;import com.itqinxun.model.Message;import java.util.List;public interface MessageDao {    public boolean addMessage(Message message);    //新增主题帖    public boolean deleteMessage(Message message); //删除主题帖,根据主题帖的ID进行删除，即message_id    public boolean deleteMessageByaccount_account(int account_account); //删除主题帖,根据用户数字账号删除该用户所有的主题帖    public List<Message> searchMessageALL();     //显示所有主题帖信息，每查询日期，只查询了message表    public List<Message> searchMessageALL2();   //按列查询，查询了日期，以及查询了account表的发帖人名字    public List<Message> searchMessageIpost(int account_account);    //根据用户Id显示该用户所有的发布主题帖    public List<Message> searchMessage(Message message);     //根据用户数字账号ID    public List<Message> searchMessageById(Message message);     //根据用户帖子ID查找帖子    public Message returnMessageBymessage_id(Message message);//显示所有主题帖信息给用户，包括发帖人名字，回帖数}

1.3、在包下创建RevertDao.java文件

内容为：

package com.itqinxun.dao;import com.itqinxun.model.Revert;import java.util.List;public interface RevertDao {    public   boolean   addRevert(Revert revert);//新增回帖    public   boolean   deleteRevert(Revert revert); //根据帖子id删除回帖    public   boolean   deleteRevertByaccount_account(int account_account);      //根据用户数字账号，删除该用户回帖    public   boolean   deleteRevertbyMessageid(int messageid);                  //根据主题帖id删除所有回帖    public     List<Revert>     searchRevertALL();//显示所有回帖    public     List<Revert>     searchNewRevertALL();//显示最新回帖    public     List<Revert>     searchRevertById(int account_account);          //根据用户id查询该用户的所有回复    public   List<Revert> returnRevertBymessage_id( int messageid);             //显示所有主题帖信息给用户，包括发帖人名字，回帖数}

至此定义了对3个Dao对象的相关需求功能，只是进行相关定义，未进行具体实现

二、对com.itqinxun.dao.impl包的实现

• 在该包中分别完成上述定义的3个Dao对象，进行具体相关代码的实现
• 以在包下创建AccountDaoImpl.java为例：

在包下创建AccountDaoImpl.java文件，内容为：

package com.itqinxun.dao.impl;import java.sql.Connection;import java.sql.PreparedStatement;import java.sql.ResultSet;import java.sql.SQLException;import java.sql.Statement;import java.util.ArrayList;import java.util.List;import com.itqinxun.dao.AccountDao;import com.itqinxun.model.Account;import com.itqinxun.util.DBUtil;public class AccountDaoImpl implements AccountDao{    Connection conn;    Statement stmt;//评测字符串执行SQL    PreparedStatement pstmt;//?编译对象占位符 可防止sql注入    ResultSet rs;    /**     *此方法是用户注册的相关方法      *@sql中的accountnum为数据库中设置的队列，调用accountnum.nextval会形成递增的数字,且为该账号表的主键！     */    public boolean addAccount(Account account) {        // TODO Auto-generated method stub        boolean flag=false;        int i=0;        // 1.定义sql        String sql="INSERT into account_table(account_account,account_name,account_pass)VALUES(accountnum.nextval,?,?)";        // 2.获得连接        conn=DBUtil.getConnection();            try {            // 3.编译sql            pstmt = conn.prepareStatement(sql);            // 4.执行sql            pstmt.setString(1, account.getAccount_name());//1,2分别对应SQL中的问号顺序            pstmt.setString(2, account.getAccount_pass());            //5.返回数据操作结行数1            i = pstmt.executeUpdate();//对结果进行判断，返回操作成功的行数，该例成功为1，失败为0            if(i>0)                flag= true;        } catch (SQLException e) {            e.printStackTrace();         }        //6.返回方法结果        //System.out.println("addAccount..........go");        return flag;    }    /**     * 这是删除用户的方法     * 根据用户数字账号进行删除，即acount_acount（用户数字账号识别列）的值     */    public boolean deleteAccount(Account account) {        boolean flag=false;        int i = 0;        String sql = "UPDATE account_table set account_limit = 2  WHERE account_account=?";         conn = DBUtil.getConnection();        try {            pstmt = conn.prepareStatement(sql);            pstmt.setInt(1, account.getAccount_account());            i = pstmt.executeUpdate();            if(i>0)                flag= true;        } catch (SQLException e) {            e.printStackTrace();        }        //System.out.println("updateAccount..........go");        return flag;    }    /**     * 保存用户修改的方法     */    public boolean updateAccount(Account account) {        // TODO Auto-generated method stub        boolean flag=false;        int i = 0;        String sql = "UPDATE account_table set account_name =?,account_pass=? WHERE account_account=?";         conn = DBUtil.getConnection();        try {            pstmt = conn.prepareStatement(sql);            pstmt.setString(1,account.getAccount_name());            pstmt.setString(2,account.getAccount_pass());            pstmt.setInt(3, account.getAccount_account());            i = pstmt.executeUpdate();            if(i>0)                flag= true;        } catch (SQLException e) {            e.printStackTrace();        }        //System.out.println("updateAccount..........go");        return flag;    }    /**     * 查询所有用户的方法，只查询普通用户，不查询管理员     */    public List<Account> searchAccountAll() {        // TODO Auto-generated method stub        List<Account> list = new ArrayList<Account>();        Account account = null;        String sql = null;        sql = "SELECT * FROM account_table WHERE account_limit=0"; //只查询普通用户        // get connection        conn = DBUtil.getConnection();        try {            // 编译sql            pstmt = conn.prepareStatement(sql);            // 执行sql            rs = pstmt.executeQuery();//executeQuery查询/executeUpdate增加、修改、删除            while (rs.next()) {                account = new Account();                account.setAccount_account(rs.getInt("account_account"));                account.setAccount_name(rs.getString("account_name"));                account.setAccount_pass(rs.getString("account_pass"));                account.setAccount_limit(rs.getInt("account_limit"));   //account_limit     用户账号权限识别码，0为用户，1为管理员                 数字类型                account.setAccount_date(rs.getDate("account_date"));   // account_date     用户账号创建日期                      list.add(account);            }        } catch (SQLException e) {            e.printStackTrace();        }           System.out.println("searchAccountAll..........go");        return list;    }    /**     * 根据用户的账号查找其他的信息，即申明一个对象，仅赋予该对象数字账号，调用该方法会把名称，密码再赋值到该对象中，更加安全     */    public Account returnAccountByaccount_account(Account account) {        String sql = "SELECT * from account_table WHERE account_account=?";        conn = DBUtil.getConnection();        try {             pstmt = conn.prepareStatement(sql);            pstmt.setInt(1, account.getAccount_account());            rs = pstmt.executeQuery();            while (rs.next()) {                account=new Account();                account.setAccount_account(rs.getInt("account_account"));                account.setAccount_name(rs.getString("account_name"));                account.setAccount_pass(rs.getString("account_pass"));            }        } catch (SQLException e) {            e.printStackTrace();        }         return account;    }    /**     * 普通用户登录方法，查询Limit<2     */    public Account loginAccount(Account account) {        // TODO Auto-generated method stub        Account newaccount=null;        String sql = "SELECT account_account,account_name,account_pass,account_date FROM account_table WHERE account_name=? and account_pass=? and account_limit<2";        conn = DBUtil.getConnection();        try {            // 编译sql            pstmt = conn.prepareStatement(sql);            pstmt.setString(1,account.getAccount_name());            pstmt.setString(2,account.getAccount_pass() );            // 执行sql            rs = pstmt.executeQuery();//executeQuery查询/executeUpdate增加、修改、删除            if(rs.next()) {                newaccount = new Account();                newaccount.setAccount_account(rs.getInt("account_account"));                newaccount.setAccount_name(rs.getString("account_name"));                newaccount.setAccount_pass(rs.getString("account_pass"));                newaccount.setAccount_date(rs.getDate("account_date"));             }        } catch (SQLException e) {            e.printStackTrace();        }           System.out.println("loginAccount..........go");        return newaccount;    }    /**     * 普通管理员登录方法，查询Limit=1才能登录     */    public Account adminloginAccount(Account account) {        // TODO Auto-generated method stub        Account newaccount=null;        String sql = "SELECT account_account,account_name,account_pass FROM account_table WHERE account_name=? and account_pass=? and account_limit=1";        conn = DBUtil.getConnection();        try {            // 编译sql            pstmt = conn.prepareStatement(sql);            pstmt.setString(1,account.getAccount_name());            pstmt.setString(2,account.getAccount_pass() );            // 执行sql            rs = pstmt.executeQuery();//executeQuery查询/executeUpdate增加、修改、删除            if(rs.next()) {                newaccount = new Account();                newaccount.setAccount_account(rs.getInt("account_account"));                newaccount.setAccount_name(rs.getString("account_name"));                newaccount.setAccount_pass(rs.getString("account_pass"));            }        } catch (SQLException e) {            e.printStackTrace();        }           System.out.println("loginAccount..........go");        return newaccount;    }    /**     * 普通所有管理员     */    public List<Account> searchAdminAll() {        // TODO Auto-generated method stub        List<Account> list = new ArrayList<Account>();        Account account = null;        String sql = null;        sql = "SELECT * FROM account_table WHERE account_limit=1"; //只查询普通用户        // get connection        conn = DBUtil.getConnection();        try {            // 编译sql            pstmt = conn.prepareStatement(sql);            // 执行sql            rs = pstmt.executeQuery();//executeQuery查询/executeUpdate增加、修改、删除            while (rs.next()) {                account = new Account();                account.setAccount_account(rs.getInt("account_account"));                account.setAccount_name(rs.getString("account_name"));                account.setAccount_pass(rs.getString("account_pass"));                account.setAccount_limit(rs.getInt("account_limit"));   //account_limit     用户账号权限识别码，0为用户，1为管理员                 数字类型                account.setAccount_date(rs.getDate("account_date"));   // account_date     用户账号创建日期                      list.add(account);            }        } catch (SQLException e) {            e.printStackTrace();        }           System.out.println("searchAccountAll..........go");        return list;    }    /**     * 设置管理员     */    public boolean setAccountAdmin(Account account) {        // TODO Auto-generated method stub        boolean flag=false;        int i = 0;        String sql = "UPDATE account_table set account_limit = 1  WHERE account_account=?";         conn = DBUtil.getConnection();        try {            pstmt = conn.prepareStatement(sql);            pstmt.setInt(1, account.getAccount_account());            i = pstmt.executeUpdate();            if(i>0)                flag= true;        } catch (SQLException e) {            e.printStackTrace();        }        //System.out.println("updateAccount..........go");        return flag;    }}

三、总结

• 至此实现了对Dao的定义及具体实现，可通过相关调用完成相应的功能，完成对数据的相关操作访问
• 在此定义好了方法，其余编程只需进行相关调用即可
• 由于分为定义与实现，也更加方便进行相关功能的修改、增加等