Dao设计模式

• 查询people表
• 具体思路
  1. 数据库连接类（工具类）、实体类、dao接口类、dao接口实现类（继承dao接口类）、工厂接口类（service类接口）、工厂接口实现类（继承工厂接口类，service实现类）
  2. 调用方式，使用工厂接口实现类中的方法来实现对数据库的操作。
• 数据库连接类

  package com.zg.shu.util;
  
  import java.sql.*;
  
  public class JDBCUtil {
      public static Connection getConnection(){
          Connection conn=null;
          try {
              String URL = "jdbc:mysql://localhost:3306/ppp?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone = GMT";
              String USER = "root";
              String PASSWORD = "hyy5201314";
              //1.加载驱动程序
              Class.forName("com.mysql.cj.jdbc.Driver");
              //2.获得数据库链接
              conn= DriverManager.getConnection(URL, USER, PASSWORD);
          }catch (SQLException e) {
              e.printStackTrace();
          }catch (ClassNotFoundException e) {
              e.printStackTrace();
          }
          return conn;
      }
  
      public static void CloseConn(Connection conn){
          try {
              if (conn!=null){
                  conn.close();
              }
          }catch (SQLException e){
              e.printStackTrace();
          }
      }
  }

   

• 实体类

  package com.zg.shu.entity;
  
  import java.io.Serializable;
  
  public class Person implements Serializable {
      private static final long serialVersionUID = 1L;
  
      private int id;
      private String name;
      private String password;
  
      public int getId() {
          return id;
      }
  
      public void setId(int id) {
          this.id = id;
      }
  
      public String getName() {
          return name;
      }
  
      public void setName(String name) {
          this.name = name;
      }
  
      public String getPassword() {
          return password;
      }
  
      public void setPassword(String password) {
          this.password = password;
      }
  }
  

   

   

• dao接口

  package com.zg.shu.dao;
  
  import com.zg.shu.entity.Person;
  
  public interface PersonDao {
      public Person findMaster(Person person);
  }

   

•  dao接口实现类

  package com.zg.shu.daoImpl;
  
  import com.zg.shu.dao.PersonDao;
  import com.zg.shu.entity.Person;
  import com.zg.shu.util.JDBCUtil;
  
  import java.sql.Connection;
  import java.sql.PreparedStatement;
  import java.sql.ResultSet;
  
  
  public class PersonDaoImpl implements PersonDao {
      @Override
      public Person findMaster(Person person) {
          Connection conne = null;
          PreparedStatement pstmt = null;
          ResultSet rs = null;
          Person person2 = null;
          String sql = "SELECT * FROM people";
  
          try {
              conne = JDBCUtil.getConnection();
  
              // 建立了到特定数据库的连接之后，就可用该连接发送 SQL 语句。
              pstmt = conne.prepareStatement(sql);
              rs = pstmt.executeQuery();
  
              if (rs.next()) {
                  person2 = new Person();
                  person2.setId(Integer.parseInt(rs.getString("id")));
                  person2.setName(rs.getString("name"));
                  person2.setPassword(rs.getString("password"));
              }
          } catch (Exception e) {
              e.printStackTrace();
          } finally {
              JDBCUtil.CloseConn(conne);
          }
          return person2;
      }
  }
  

   

   

•  

  dao工厂接口 

  package com.zg.shu.service;
  
  import com.zg.shu.entity.Person;
  
  public interface PersonService {
      public boolean login(Person person);
  }

   

   

• dao工厂实现类

  package com.zg.shu.serviceImpl;
  
  import com.zg.shu.dao.PersonDao;
  import com.zg.shu.daoImpl.PersonDaoImpl;
  import com.zg.shu.entity.Person;
  import com.zg.shu.service.PersonService;
  
  public class PersonServiceImpl implements PersonService {
      @Override
      public boolean login(Person person) {
          boolean isLogin=false;
          PersonDao pd=new PersonDaoImpl();
          Person ps2=pd.findMaster(person);
          if (null!=ps2){
              return true;
          }
          return false;
      }
  }
  

   
•  调用

  package com.zg.shu.test;
  
  import com.zg.shu.entity.Person;
  import com.zg.shu.service.PersonService;
  import com.zg.shu.serviceImpl.PersonServiceImpl;
  
  import java.util.Scanner;
  
  public class LoginTest {
      public String Login(){
          String loginName="11";
          String loginPassword="22";
          Person person = new Person();
          person.setName(loginName);
          person.setPassword(loginPassword);
  
          PersonService ps = new PersonServiceImpl();
          boolean isLoginid = ps.login(person);
  
          if (isLoginid) {
              System.out.println("登录成功");
          } else {
              System.out.println("用户名或密码错误");
          }
          return isLoginid+"";
      }
  }