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

     }
 }