36、Java——一个案例学会三层架构对数据表的增删改查

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🥭本文内容:一个案例学会三层架构对数据表的增删改查

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文章目录

reactjs

在这里插入图片描述

毕业设计论文写法

案例要求

  使用读取配置文件的形式连接数据库,利用三层架构对book表进行增删改查操作。增加了接口知识点的优化,便于方法名的统一命名。

源码+论文

book表字段如下
  bid int 非空 主键 自增长 唯一 –>图书编号
  isbn varchar(20) 非空 唯一 –>国际标准书号
  name varchar(20) 非空 –>书名
  author varchar(20) 非空 –>作者
  press varchar(20) 非空 –>出版社
  press double 非空 –>价格
  classification varchar(20) 非空 –>分类

ShaderGraph

建book表

CREATE TABLE `book` (
  `bid` int(11) NOT NULL AUTO_INCREMENT COMMENT '图书编号',
  `isbn` varchar(20) 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',
  PRIMARY KEY (`bid`),
  UNIQUE KEY `isbn` (`isbn`)
) 
);

配置连接数据库

  添加mysql-connector-java-5.1.0-bin.jar文件并使用。
  添加db.properties文件

窗口函数

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/java221803
username=root
password=huanghuang

策略模式

创建实体类:Book类

  定义一个Book类,添加和Book表字段相同的私有变量

turtle

	// 定义属性
	private int bid;
	private String isbn;
	private String name;
	private String author;
	private String press;
	private double price;
	private String classification;

  添加一个无参构造

keychron

	public Book() {
		super();
	}

  添加一个全部字段的有参构造

html5

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

  添加一个不带aid字段的有参构造

自动生成

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

  给私有变量添加get/set方法

业务安全

	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;
	}

  重写ToString方法

分享到朋友圈

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

工具类

  将一些重复的功能封装成一些工具。

select选择器

DBUtils数据库工具类

  声明一个ThreadLocal对象,用来存储Connection连接对象;注册驱动、获取连接、然后释放资源方法。

pcb设计制作

	private static final Properties PROPERTIES = new Properties();
	// 声明一个ThreadLocal<Connection>对象,用来存储Connection连接对象
	private static ThreadLocal<Connection> threadLocal = new ThreadLocal<Connection>();

	static {
		InputStream is = DBUtils.class.getResourceAsStream("/db.properties");
		try {
			PROPERTIES.load(is);
			// 1、注册驱动
			Class.forName(PROPERTIES.getProperty("driver"));
		} catch (IOException e) {
			e.printStackTrace();
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
	}
		// 2、获取连接方法
	public static Connection getConnection() {
		Connection connection = threadLocal.get();
		// 2、获取连接对象
		try {
			// 如果连接对象为null,创建一个连接对象
			if (connection == null) {
				connection = DriverManager.getConnection(
						PROPERTIES.getProperty("url"),
						PROPERTIES.getProperty("username"),
						PROPERTIES.getProperty("password"));
				threadLocal.set(connection);
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
		return connection;

	}

	// 3、释放资源方法
	public static void closeAll(ResultSet resultSet, Statement statement,
			Connection connection) {
		try {
			if (resultSet != null) {
				resultSet.close();
			}
			if (statement != null) {
				statement.close();
			}
			if (connection != null) {
				connection.close();
				// 移除 ThreadLocal<Connection> 对象
				threadLocal.remove();
			}
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

  开启事务

ERC1155 协议详解

	public static void startTransaction() {
		Connection connection = getConnection();
		try {
			connection.setAutoCommit(false);
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

  提交事务

求职招聘

	public static void commitTransaction() {
		Connection connection = getConnection();
		try {
			connection.commit();
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			DBUtils.closeAll(null, null, connection);
		}
	}

  回滚事务

DNS

	public static void rollbackTransaction() {
		Connection connection = getConnection();
		try {
			connection.rollback();
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			DBUtils.closeAll(null, null, connection);
		}
	}

DateUtils日期类

public class DateUtils {
	// 声明一个SimpleDateFormat类型的静态常量
	public static final SimpleDateFormat SIMPLEDATEFORMAT=new SimpleDateFormat("yyyy-MM-dd");

	// 定义方法实现将字符串类型的数据转换成java.util.Date类型
	public static java.util.Date strToUtilDate(String strDate){
		try {
			return SIMPLEDATEFORMAT.parse(strDate);
		} catch (ParseException e) {
			e.printStackTrace();
		}
		return null;
	}

	// 定义方法实现将java.util.Date类型转换为字符串
	public static String utilDateToString(java.util.Date utilDate){
		return SIMPLEDATEFORMAT.format(utilDate);
	}
	
	// 定义方法实现架构java.util.Date类型转换为java.sql.Date类型
	public static java.sql.Date utilDateToSqlDate(java.util.Date utilDate){
		return new java.sql.Date(utilDate.getTime());
	}
}

数据访问层DAO层

  DAO层叫数据访问层,全称为data access object,属于一种比较底层,比较基础的操作,具体到对于某个表的增删改查,也就是说某个DAO一定是和数据库的某一张表一一对应的,其中封装了增删改查基本操作,建议DAO只做原子操作,增删改查。

Spring Boot

BookDao接口

package cn.bdqn.dao;
import java.util.List;
import cn.bdqn.entity.Book;

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();
}

BookDaoImpl类(实现BookDao接口)

package cn.bdqn.dao.lmpl;

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

import cn.bdqn.dao.BookDao;
import cn.bdqn.entity.Book;
import cn.bdqn.utils.DBUtils;

public class BookDaoImpl implements BookDao {

	//全局变量
	PreparedStatement preS=null;
	Connection connection;
	
	@Override
	public int insert(Book book) {
		
		//获取链接
		connection=DBUtils.getConnection();
		String sql="insert into book(isbn,name,author,press,price,classification) values(?,?,?,?,?,?);";
		
		try {
			preS=connection.prepareStatement(sql);
			// 绑定参数
//			preS.setInt(1, book.getBid());
			preS.setString(1, book.getIsbn());
			preS.setString(2, book.getName());
			preS.setString(3, book.getAuthor());
			preS.setString(4, book.getPress());
			preS.setDouble(5, book.getPrice());
			preS.setString(6, book.getClassification());
			
			return preS.executeUpdate();
		} catch (SQLException e) {
			e.printStackTrace();
		}finally{
			DBUtils.closeAll(null, preS, null);
		}		
		return 0;
	}

	@Override
	public int delete(int bid) {
		//获取链接
		connection = DBUtils.getConnection();
		String sql = "delete from book where bid = ?;";
		
		try {
			preS = connection.prepareStatement(sql);
			// 绑定参数
			preS.setInt(1, bid);
			
			return preS.executeUpdate();
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			DBUtils.closeAll(null, preS, null);
		}
		return 0;
	}

	@Override
	public int update(Book book) {
		//获取链接
		connection = DBUtils.getConnection();
		String sql = "update book set isbn = ?,name = ?, author= ?,press = ?,price = ?,classification = ? where bid=?;";

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

			return preS.executeUpdate();
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			DBUtils.closeAll(null, preS, null);
		}
		return 0;
	}

	@Override
	public Book selectOne(int bid) {
		ResultSet resultSet = null;
		Book book = null;

		//获取连接
		connection = DBUtils.getConnection();
		String sql = "select * from book where bid = ?";

		try {
			preS = connection.prepareStatement(sql);

			// 绑定参数
			preS.setInt(1, bid);
			resultSet = preS.executeQuery();

			if (resultSet.next()) {
				book=new Book(bid, resultSet.getString(2), resultSet.getString(3),resultSet.getString(4)
						,resultSet.getString(5),resultSet.getDouble(6),resultSet.getString(7));
			}

			return book;
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			DBUtils.closeAll(resultSet, preS, null);
		}
		return null;
	}

	@Override
	public List<Book> selectAll() {
		ResultSet resultSet = null;
		Book book = null;
		List<Book> bookList = new ArrayList<Book>();

		//获取连接
		connection = DBUtils.getConnection();
		String sql = "select * from book";

		try {
			preS = connection.prepareStatement(sql);
			resultSet = preS.executeQuery();

			while (resultSet.next()) {
				book=new Book(resultSet.getInt(1), resultSet.getString(2), resultSet.getString(3),resultSet.getString(4)
						,resultSet.getString(5),resultSet.getDouble(6),resultSet.getString(7));
				bookList.add(book);
			}

			return bookList;
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {
			DBUtils.closeAll(resultSet, preS, null);
		}
		return null;
	}

}

服务层Service层

  Service层叫服务层,被称为服务,粗略的理解就是对一个或多个DAO进行的再次封装,封装成一个服务,所以这里也就不会是一个原子操作了,需要事物控制。

uniapp

BookService接口

package cn.bdqn.service;

import java.util.List;

import cn.bdqn.entity.Book;

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();
}

BookServiceImpl类(实现BookService接口)

package cn.bdqn.service.Impl;

import java.util.List;

import cn.bdqn.dao.lmpl.BookDaoImpl;
import cn.bdqn.entity.Book;
import cn.bdqn.service.BookService;

public class BookServiceImpl implements BookService {

	// 定义PeopleDaoImpl对象
	BookDaoImpl bookDaoImpl = new BookDaoImpl();

	@Override
	public int addBook(Book book) {
		int num=bookDaoImpl.insert(book);
		return num;
	}

	@Override
	public int deleteBook(int bid) {
		int num=bookDaoImpl.delete(bid);
		return num;
	}

	@Override
	public int updateBook(Book book) {
		int num=bookDaoImpl.update(book);
		return num;
	}

	@Override
	public Book selectOne(int bid) {
		Book book=bookDaoImpl.selectOne(bid);
		return book;
	}

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

视图层View层

TestBookServiceImpl测试类

package cn.bdqn.view;
import java.util.List;
import cn.bdqn.entity.Book;
import cn.bdqn.service.Impl.BookServiceImpl;

public class TestBookServiceImpl {

	public static void main(String[] args) {

		// 创建BookServiceImpl对象
		BookServiceImpl bookServiceImpl = new BookServiceImpl();

		// 增
		Book book = new Book("977-8-3154-6587-3", "jQuery从入门到精通", "王五",
				"北京大学出版社", 88.88, "前端开发");
		if (bookServiceImpl.addBook(book) != 0) {
			System.out.println("图书添加成功!");
		}
		
		// 删
		if (bookServiceImpl.deleteBook(1001)!= 0) {
			System.out.println("图书删除成功!");
		}
		
		//改
		Book book1 = new Book(1003, "977-8-3154-6587-4", "jQuery从入门到精通", "王六",
				"北京大学出版社", 88.88, "前端开发");
		if (bookServiceImpl.updateBook(book1)!= 0) {
			System.out.println("图书修改成功!");
		}
		
		//查
		if(bookServiceImpl.selectOne(1002)!=null)
		{
			System.out.println("图书查询成功!图书信息为:"+bookServiceImpl.selectOne(1002).toString());
		}
		
		//查所有
		List<Book> bookList=bookServiceImpl.selectAll();
		if(bookList.size()>0){
			System.out.println("查询到所有图书为:");
			for (Book book2 : bookList) {
				System.out.println(book2);
			}
		}
		
	}
}

完整代码

book表的三层架构完整代码

Java 定时任务

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string

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