DAO模式应用实例

首先在数据库中建好一个表。

然后创建一个MsterDao类的接口

package com.beiwo.epte.dao;

import com.beiwo.epte.entity.Master;

public interface MasterDao extends BaseDao{

    /**
     * 保存主人
     * @param pet
     * @return
     */
    int save(Master master);
    
    
    /**
     * 删除主人
     * @param pet
     * @return
     */
    int del(Master master);
    
    /**
     * 更新主人
     * @param pet
     * @return
     */
    int update(Master master);
    
    /**
     * 根据Master对象进行查询
     * @param master
     * @return
     */
    Master findMaster(Master master);
    
}

然后创建这个MasterDao的实现类

package com.beiwo.epte.dao.impl;

import java.sql.Connection;
import java.sql.PreparedStatement;

import com.beiwo.epte.dao.MasterDao;
import com.beiwo.epte.entity.Master;
import com.beiwo.epte.util.DBUtils;
import java.sql.ResultSet;

public class MasterDaoMySqllmpl extends BaseDaoImpl implements MasterDao {

    @Override
    public int save(Master master) {
        // TODO Auto-generated method stub
        return 0;
    }

    @Override
    public int del(Master master) {
        // TODO Auto-generated method stub
        return 0;
    }

    @Override
    public int update(Master master) {
        // TODO Auto-generated method stub
        return 0;
    }

    @Override
    public Master findMaster(Master master) {
        Master master2 = null;

        Connection connection = null;
        PreparedStatement pastmt = null;
        ResultSet rSet = null;

        String sql = "SELECT * FROM master WHERE loginId=? AND password=?";

        try {
            connection = DBUtils.getConn();
            pastmt = connection.prepareStatement(sql);
            pastmt.setString(1, master.getLoginId());
            pastmt.setString(2, master.getPassword());

            rSet = pastmt.executeQuery();
            //指针下移
            if (rSet.next()) {
                master2 = new Master();
                master2.setId(rSet.getInt("id"));
                master2.setLoginId(rSet.getString("loginId"));
                master2.setPassword(rSet.getString("password"));

            }
        } catch (Exception e) {
            // TODO: handle exception
        } finally {
            DBUtils.closeAll(rSet, pastmt, connection);

        }

        return master2;
    }

}

创建Master的实体类

package com.beiwo.epte.entity;

import java.io.Serializable;

public class Master implements Serializable{

    private int id;  //ID
    private String loginId;//用户名
    private String password;//密码
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getLoginId() {
        return loginId;
    }
    public void setLoginId(String loginId) {
        this.loginId = loginId;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    
}

数据库的帮助类

package com.beiwo.epte.util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ResourceBundle;

/**
 * 数据库的帮助类
 * 
 * @author beiwo
 *
 */
public class DBUtils {

    private static String driverClass;
    private static String url;
    private static String user;
    private static String password;
    
    static{
        ResourceBundle rb=ResourceBundle.getBundle("jdbc");
        driverClass=rb.getString("driverClass");
        url=rb.getString("url");
        user=rb.getString("user");
        password=rb.getString("password");
        
        try {
            Class.forName(driverClass);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }
    

    public static Connection getConn() throws Exception {
        return DriverManager.getConnection(url, user, password);
    }
    
    
    public static void closeAll(ResultSet rs,Statement stmt,Connection conn){
        //關閉資源
        if(null!=rs){
            try {
                rs.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        if(null!=stmt){
            try {
                stmt.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        
        if(null!=conn){
            try {
                conn.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
    
    
    

}

然后再创建一个接口声明一个登陆的方法

package com.beiwo.epte.service;

public interface MsterService {
    
    //登陆
    public void login();
    

}

然后创建一个实现类来实现以下这个登陆的方法

package com.beiwo.epte.service.impl;

import java.util.Scanner;

import com.beiwo.epte.dao.MasterDao;
import com.beiwo.epte.dao.impl.MasterDaoMySqllmpl;
import com.beiwo.epte.entity.Master;
import com.beiwo.epte.service.MsterService;

public class MasterServiceImpl implements MsterService{

    Master master = null;
    @Override
    public void login() {
        
        Scanner scanner = new Scanner(System.in);
        
        System.out.println("请输入用户名:");
        String loginId = scanner.next();
        
        System.out.println("请输入密码:");
        String password = scanner.next();
        
        MasterDao masterDao = new MasterDaoMySqllmpl();
        Master master2 = new Master();
        master2.setLoginId(loginId);
        master2.setPassword(password);
        
        master=masterDao.findMaster(master2);
        
        if (null!=master) {
            System.out.println("登陆成功");
        } else {
            System.out.println("登陆失败");
        }
        
    }
}

最后创建一个测试类来调用一下这个方法，只要是输入正确都可以登陆成功。

package com.beiwo.epte.test;

import org.junit.Test;

import com.beiwo.epte.service.MsterService;
import com.beiwo.epte.service.impl.MasterServiceImpl;

public class TestMasterDao {
    @Test
    public void testLogin(){
        MsterService masterService = new MasterServiceImpl();
        masterService.login();//调用登陆的方法
        
    }
}