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【JAVA高级】——玩转JDBC中的三层架构

最不爱吃鱼 2022-11-26 阅读 122
java架构数据库sqlideLinux系统/运维


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🥭本文内容：【JAVA高级】——玩转JDBC中的三层架构
更多内容点击👇
       【JAVA高级】——吃透JDBC中的事务及事务的封装

文章目录

  • ​​什么是三层​​
  • ​​三层架构项目搭建步骤​​
  • ​​项目环境搭建​​
  • ​​创建book表​​
  • ​​创建表​​
  • ​​向表中插入数据​​
  • ​​创建entity实体类Book​​
  • ​​创建BookDao接口​​
  • ​​创建BookDaoImpl实现类​​
  • ​​创建BookService接口​​
  • ​​创建BookServiceImpl实现类​​
  • ​​编写测试类​​
  • ​​测试增加数据​​
  • ​​测试删除数据​​
  • ​​测试修改数据​​
  • ​​测试查询单个​​
  • ​​测试查询所有​​

【JAVA高级】——玩转JDBC中的三层架构_java

什么是三层

（1）表示层（View）

  • 命名：XxxView
  • 职责：收集用户的数据和需求、数据

（2）业务逻辑层（service）

  • 命名：XxxServiceImpl
  • 职责：数据加工处理、调用DAO完成业务实现、控制事务

（3）数据访问层（Dao）

  • 命名：XxxDaoImpl
  • 职责：向业务层提供数据，将业务层加工后的数据同步到数据库

【JAVA高级】——玩转JDBC中的三层架构_架构_02

三层架构项目搭建步骤

项目环境搭建

1）新建一个项目，在项目中创建lib文件夹，将MySQL数据库jar包放在lib文件夹中，配置环境。

2）在src文件夹下面创建db.properties文件，编写数据库driver、url、user、password信息。

3）创建三层需要的各个包。

（1）utils包：存放工具类（DBUtils类、DateUtils类）

（2）entity包：存放实体类（Xxx.java）

（3）dao包：存放DAO接口

    impl包：存放DAO接口实现类

（4）service包：存放service接口

    impl：存放service接口实现类

（5）view包：存放程序启动类或测试类（main）

创建book表

创建表

CREATE TABLE IF NOT EXISTS `book`(
`bid` INT PRIMARY KEY AUTO_INCREMENT COMMENT '图书编号',
`isbn` VARCHAR(20) UNIQUE NOT NULL COMMENT '国际标准书号',
`name` VARCHAR(20) NOT NULL COMMENT '书名',
`author` VARCHAR(20) NOT NULL COMMENT '作者',
`press` VARCHAR(20) NOT NULL COMMENT '出版社',
`price` DOUBLE NOT NULL COMMENT '价格',
`classification` VARCHAR(20) NOT NULL COMMENT '分类'
);

向表中插入数据

INSERT INTO `book`(`bid`,`isbn`,`name`,`author`,`press`,`price`,`classification`)
VALUES
(1001,'978-7-5170-7654-4','SQL从入门到精通','张三','中国水利水电出版社',79.80,'数据库');

INSERT INTO `book`(`bid`,`isbn`,`name`,`author`,`press`,`price`,`classification`)
VALUES
(1002,'976-9-5245-7633-5','java从入门到精通','李四','清华大学出版社',99.80,'程序设计');

创建entity实体类Book

package com.cxyzxc.www.entity;

import java.util.Date;

/**
 * entity实体类Booke类
 */
public class Book {
  /** 图书编号 */
  private int bid;
  /** 国际标准书号 */
  private String isbn;
  /** 书名 */
  private String name;
  /** 作者 */
  private String author;
  /** 出版社 */
  private String press;
  /** 价格 */
  private double price;
  /** 分类 */
  private String classification;
  /** 出版日期 */
  private Date pubdate;

  public Book() {
    super();
  }

  public Book(String isbn, String name, String author, String press,
      double price, String classification, Date pubdate) {
    super();
    this.isbn = isbn;
    this.name = name;
    this.author = author;
    this.press = press;
    this.price = price;
    this.classification = classification;
    this.pubdate = pubdate;
  }

  public Book(int bid, String isbn, String name, String author, String press,
      double price, String classification, Date pubdate) {
    super();
    this.bid = bid;
    this.isbn = isbn;
    this.name = name;
    this.author = author;
    this.press = press;
    this.price = price;
    this.classification = classification;
    this.pubdate = pubdate;
  }

  public int getBid() {
    return bid;
  }

  public void setBid(int bid) {
    this.bid = bid;
  }

  public String getIsbn() {
    return isbn;
  }

  public void setIsbn(String isbn) {
    this.isbn = isbn;
  }

  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

  public String getAuthor() {
    return author;
  }

  public void setAuthor(String author) {
    this.author = author;
  }

  public String getPress() {
    return press;
  }

  public void setPress(String press) {
    this.press = press;
  }

  public double getPrice() {
    return price;
  }

  public void setPrice(double price) {
    this.price = price;
  }

  public String getClassification() {
    return classification;
  }

  public void setClassification(String classification) {
    this.classification = classification;
  }

  public Date getPubdate() {
    return pubdate;
  }

  public void setPubdate(Date pubdate) {
    this.pubdate = pubdate;
  }

  @Override
  public String toString() {
    return "Book [bid=" + bid + ", isbn=" + isbn + ", name=" + name
        + ", author=" + author + ", press=" + press + ", price="
        + price + ", classification=" + classification + ", pubdate="
        + pubdate + "]";
  }

}

创建BookDao接口

package com.cxyzxc.www.dao;

import java.util.List;

import com.cxyzxc.www.entity.Book;
/**
 * 定义BookDao接口，接口中定义对book表增删改查的方法
 */
public interface BookDao {
  
  //增
  int insert(Book book);
  
  //删
  int delete(int bid);
  
  //改
  int update(Book book);
  
  //查单个
  Book selectOne(int bid);
  
  //查所有
  List<Book> selectAll();

}

创建BookDaoImpl实现类

package com.cxyzxc.www.dao.impl;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import com.cxyzxc.www.dao.BookDao;
import com.cxyzxc.www.entity.Book;
import com.cxyzxc.www.utils.DBUtils;
import com.cxyzxc.www.utils.DateUtils;
/**
 * 定义BookDaoImpl类，实现BookDao接口，重写接口中的增删改查方法
 */
public class BookDaoImpl implements BookDao {

  @Override
  public int insert(Book book) {
    Connection connection = null;
    PreparedStatement preparedStatement = null;

    connection = DBUtils.getConnection();

    String sql = "INSERT INTO `book`(`isbn`,`name`,`author`,`press`,`price`,`classification`,`pubdate`)VALUES(?,?,?,?,?,?,?);";

    try {
      preparedStatement = connection.prepareStatement(sql);
      // 绑定参数
      preparedStatement.setString(1, book.getIsbn());
      preparedStatement.setString(2, book.getName());
      preparedStatement.setString(3, book.getAuthor());
      preparedStatement.setString(4, book.getPress());
      preparedStatement.setDouble(5, book.getPrice());
      preparedStatement.setString(6, book.getClassification());
      preparedStatement.setDate(7,
          DateUtils.utilDateToSqlDate(book.getPubdate()));

      int result = preparedStatement.executeUpdate();
      return result;
    } catch (SQLException e) {
      e.printStackTrace();
    }
    return 0;
  }

  @Override
  public int delete(int bid) {
    Connection connection = null;
    PreparedStatement preparedStatement = null;

    connection = DBUtils.getConnection();

    String sql = "DELETE FROM `book` WHERE `bid`=?;";

    try {
      preparedStatement = connection.prepareStatement(sql);
      // 绑定参数
      preparedStatement.setInt(1, bid);
      int result = preparedStatement.executeUpdate();
      return result;
    } catch (SQLException e) {
      e.printStackTrace();
    }
    return 0;
  }

  @Override
  public int update(Book book) {
    Connection connection = null;
    PreparedStatement preparedStatement = null;

    connection = DBUtils.getConnection();

    String sql = "UPDATE `book` SET `isbn`=?,`name`=?,`author`=?,`press`=?,`price`=?,`classification`=?,`pubdate`=? WHERE `bid`=?;";

    try {
      preparedStatement = connection.prepareStatement(sql);
      // 绑定参数
      preparedStatement.setString(1, book.getIsbn());
      preparedStatement.setString(2, book.getName());
      preparedStatement.setString(3, book.getAuthor());
      preparedStatement.setString(4, book.getPress());
      preparedStatement.setDouble(5, book.getPrice());
      preparedStatement.setString(6, book.getClassification());
      preparedStatement.setDate(7,
          DateUtils.utilDateToSqlDate(book.getPubdate()));
      preparedStatement.setDouble(8, book.getBid());

      int result = preparedStatement.executeUpdate();
      return result;
    } catch (SQLException e) {
      e.printStackTrace();
    }
    return 0;
  }

  @Override
  public Book selectOne(int bid) {
    Connection connection = null;
    PreparedStatement preparedStatement = null;
    ResultSet resultSet = null;
    Book book = null;
    connection = DBUtils.getConnection();

    String sql = "Select * FROM `book` WHERE `bid`=?;";
    try {
      preparedStatement = connection.prepareStatement(sql);
      // 绑定参数
      preparedStatement.setInt(1, bid);

      resultSet = preparedStatement.executeQuery();

      if (resultSet.next()) {
        int bookid = resultSet.getInt(1);
        String isbn = resultSet.getString(2);
        String name = resultSet.getString(3);
        String author = resultSet.getString(4);
        String press = resultSet.getString(5);
        double price = resultSet.getDouble(6);
        String classification = resultSet.getString(7);
        Date pubdate = resultSet.getDate(8);
        book = new Book(bookid, isbn, name, author, press, price,
            classification, pubdate);
      }
      return book;
    } catch (SQLException e) {
      e.printStackTrace();
    }
    return null;
  }

  @Override
  public List<Book> selectAll() {

    Connection connection = null;
    PreparedStatement preparedStatement = null;
    ResultSet resultSet = null;
    Book book = null;
    List<Book> bookList = new ArrayList<Book>();
    connection = DBUtils.getConnection();

    String sql = "Select * FROM `book`;";
    try {
      preparedStatement = connection.prepareStatement(sql);

      resultSet = preparedStatement.executeQuery();

      while (resultSet.next()) {
        int bookid = resultSet.getInt(1);
        String isbn = resultSet.getString(2);
        String name = resultSet.getString(3);
        String author = resultSet.getString(4);
        String press = resultSet.getString(5);
        double price = resultSet.getDouble(6);
        String classification = resultSet.getString(7);
        Date pubdate = resultSet.getDate(8);
        book = new Book(bookid, isbn, name, author, press, price,
            classification, pubdate);
        bookList.add(book);
      }
      return bookList;
    } catch (SQLException e) {
      e.printStackTrace();
    }

    return null;
  }

}

创建BookService接口

package com.cxyzxc.www.service;

import java.util.List;

import com.cxyzxc.www.entity.Book;
/**
 * 定义BookService接口，接口中定义业务逻辑方法
 */
public interface BookService {
  //添加图书
  int addBook(Book book);
  
  //删除图书
  int deleteBook(int bid);
  
  //修改图书
  int updateBook(Book book);
  
  //查询一本图书
  Book selectOne(int bid);
  
  //查询所有图书
  List<Book> selectAll();

}

创建BookServiceImpl实现类

package com.cxyzxc.www.service.impl;

import java.util.List;

import com.cxyzxc.www.dao.BookDao;
import com.cxyzxc.www.dao.impl.BookDaoImpl;
import com.cxyzxc.www.entity.Book;
import com.cxyzxc.www.service.BookService;
/**
 * 定义BookServiceImpl类，实现BookService接口，重写BookService接口中的所有方法
 */
public class BookServiceImpl implements BookService {

  BookDao bookDao = new BookDaoImpl();

  @Override
  public int addBook(Book book) {
    // 首先查询一下插入的图书在数据库中是否存在
    Book book2 = bookDao.selectOne(book.getBid());
    if (book2 == null) {
      return bookDao.insert(book);
    } else {
      System.out.println("插入的图书已经存在，插入失败");
    }
    return 0;
  }

  @Override
  public int deleteBook(int bid) {
    // 查询要删除的图书是否存在
    Book book2 = bookDao.selectOne(bid);
    if (book2 == null) {
      System.out.println("删除的图书不存在，无法删除");
    } else {
      return bookDao.delete(bid);
    }
    return 0;
  }

  @Override
  public int updateBook(Book book) {
    // 查询要修改的图书是否存在
    Book book2 = bookDao.selectOne(book.getBid());
    if (book2 == null) {
      System.out.println("你要修改的图书不存在");
    } else {
      return bookDao.update(book);
    }
    return 0;
  }

  @Override
  public Book selectOne(int bid) {
    Book book2 = bookDao.selectOne(bid);
    return book2;
  }

  @Override
  public List<Book> selectAll() {
    List<Book> bookList = bookDao.selectAll();
    return bookList;
  }

}

编写测试类

测试增加数据

package com.cxyzxc.www.view;

import com.cxyzxc.www.entity.Book;
import com.cxyzxc.www.service.BookService;
import com.cxyzxc.www.service.impl.BookServiceImpl;
import com.cxyzxc.www.utils.DateUtils;

public class Test01InsertBook {

  public static void main(String[] args) {

    BookService bookService = new BookServiceImpl();

    // 添加图书
    Book book = new Book("978-9-9456-3286-9", "JSP从入门到精通", "李二狗", "邮电出版社",129, "编程设计", DateUtils.strDateToUtilDate("2022-01-13"));
    int result = bookService.addBook(book);
    if (result == 1) {
      System.out.println("图书添加成功");
    } else {
      System.out.println("图书添加失败");
    }

  }

}

测试删除数据

package com.cxyzxc.www.view;

import com.cxyzxc.www.service.BookService;
import com.cxyzxc.www.service.impl.BookServiceImpl;

public class Test02DeleteBook {

  public static void main(String[] args) {

    BookService bookService = new BookServiceImpl();

    // 删除图书
    int result = bookService.deleteBook(1003);
    if (result == 1) {
      System.out.println("删除成功");
    } else {
      System.out.println("删除失败");
    }
    
  }

}

测试修改数据

package com.cxyzxc.www.view;

import com.cxyzxc.www.entity.Book;
import com.cxyzxc.www.service.BookService;
import com.cxyzxc.www.service.impl.BookServiceImpl;
import com.cxyzxc.www.utils.DateUtils;

public class Test03UpdateBook {

  public static void main(String[] args) {

    BookService bookService = new BookServiceImpl();

    // //修改图书
    Book book = new Book(1002, "976-9-5245-7633-5", "JSP从入门到放弃", "李四","清华大学出版社", 109.8, "编程设计",DateUtils.strDateToUtilDate("2022-10-13"));

    int result = bookService.updateBook(book);
    if (result == 1) {
      System.out.println("修改成功");
    } else {
      System.out.println("修改失败");
    }

  }

}

测试查询单个

package com.cxyzxc.www.view;

import com.cxyzxc.www.entity.Book;
import com.cxyzxc.www.service.BookService;
import com.cxyzxc.www.service.impl.BookServiceImpl;

public class Test04SelectOneBook {

  public static void main(String[] args) {

    BookService bookService = new BookServiceImpl();

    Book book = bookService.selectOne(1003);
    if (book == null) {
      System.out.println("没有你要查找的图书");
    } else {
      System.out.println(book);
    }
  }

}

测试查询所有

package com.cxyzxc.www.view;

import java.util.List;

import com.cxyzxc.www.entity.Book;
import com.cxyzxc.www.service.BookService;
import com.cxyzxc.www.service.impl.BookServiceImpl;

public class Test05SelectAllBook {

  public static void main(String[] args) {

    BookService bookService = new BookServiceImpl();

    List<Book> books = bookService.selectAll();
    if (books.isEmpty()) {

      System.out.println("数据库里没有书的数据");
    } else {
      for (int i = 0; i < books.size(); i++) {
        System.out.println(books.get(i));
      }
    }
  }

}

【JAVA高级】——玩转JDBC中的三层架构_sql_03


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