表述MVC与JDBC的基本操作

本文介绍了MVC模式的基本概念,包括模型、视图和控制器的职责,并详细阐述了使用JDBC进行数据增删改查的操作,涵盖了从数据库连接到Book对象的映射。同时,给出了代码示例,帮助读者理解Java开发中的这些基础概念。

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我对MVC的理解

MVC全名是Model View Controller,是模型(model)-视图(view)-控制器(controller)的缩写

  • 模型(model):接收信息,进行数据库的存取
  • 视图(view):用户看到的界面(如jsp、html等界面)
  • 控制器(controller):接收用户需求,调用模型完成用户需求

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JDBC的基本操作(实现数据的增删改查)

对Book表中的数据进行增删改查;
Book表:id int,bookName varchar,price int,description varchar
Book类:id int,bookName String ,price int,description String
DBUtil类:创建数据库连接

Book表:原有3条信息

Book类:

public class Book {
	private int id;
	private String bookName;
	private int price;
	private String description;
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getBookName() {
		return bookName;
	}
	public void setBookName(String bookName) {
		this.bookName = bookName;
	}
	public int getPrice() {
		return price;
	}
	public void setPrice(int price) {
		this.price = price;
	}
	public String getDescription() {
		return description;
	}
	public void setDescription(String description) {
		this.description = description;
	}
	public String toString(){
		return "id:"+id+"bookname:"+bookName+"price:"+price+"description:"+description;
	}
}

DBUtil类:

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.Statement;
public class DBUtil {
	static Connection conn = null;
    Statement stmt = null;
	static String driverClassName="com.mysql.jdbc.Driver";
	static String url="jdbc:mysql://localhost:3306/goods";
	static String username="root";
	static String password="123456";
	public static Connection getConn(){
		try {
			Class.forName(driverClassName);
			conn = DriverManager.getConnection(url,username,password);
		} catch (Exception e) {
			e.printStackTrace();
			System.out.println("失败");
		}
		return conn;
	}
}

BookTest类:

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class BookTest {
	public static void main(String[] args) {
		Book book = new Book();
		book.setId(4);
		book.setBookName("计算机英语");
		book.setPrice(20);
		book.setDescription("太难了");
		addBook(book);//添加
		deleteBookById(4);//删除id为4的信息
		findBookById(1);//查找id为1的信息
		Book book1 = new Book();
		book1.setId(3);//修改id为3的信息
		book1.setBookName("H5");
		book1.setPrice(20);
		book1.setDescription("从入门到学Java");
		updateBook(book1);//修改
	}
	//添加 
	public static void addBook(Book book) {
		Connection conn = DBUtil.getConn();
        PreparedStatement pstmt;
        try {
        	if (conn ==null) {
				System.out.println("conn is null");
			}
            pstmt = conn.prepareStatement("insert into Book(id,bookName,price,description) values(?,?,?,?)");
            pstmt.setInt(1, book.getId());
            pstmt.setString(2, book.getBookName());
            pstmt.setInt(3, book.getPrice());
            pstmt.setString(4,book.getDescription());
            int rs = pstmt.executeUpdate();
            System.out.println(rs+"添加成功");
        } catch (SQLException e) {
            e.printStackTrace();
        }
	}
	//根据id实现删除
    public static void deleteBookById(int id){
    	Connection conn = DBUtil.getConn();
        PreparedStatement pstmt;
        try {
            pstmt = conn.prepareStatement("delete from Book where id=?");
            pstmt.setInt(1, id);
            int rs = pstmt.executeUpdate();
            System.out.println(rs+"删除成功");
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    //根据id实现查找
    public static Book findBookById(Integer id){
        Connection conn = DBUtil.getConn();
        PreparedStatement pstmt;
        Book book = new Book();
        try {
            pstmt = conn.prepareStatement("select * from Book where id = ?");
            pstmt.setInt(1, id);
            ResultSet rs = pstmt.executeQuery();
            while (rs.next()) {
            	book.setId(rs.getInt("id"));
            	book.setBookName(rs.getString("bookname"));
            	book.setPrice(rs.getInt("price"));
                book.setDescription(rs.getString("description"));
                System.out.println(book);
            }
        } catch (SQLException e) {
            
            e.printStackTrace();
        }

        return book;
    }
    //根据id实现修改
    public static void updateBook(Book book){
        Connection conn = DBUtil.getConn();
        PreparedStatement pstmt;
        try {
            pstmt = conn.prepareStatement("update Book set bookname=?,price=?,description=? where id=?");
            pstmt.setInt(4, book.getId());
            pstmt.setString(1, book.getBookName());
            pstmt.setInt(2, book.getPrice());
            pstmt.setString(3,book.getDescription());
            int rs = pstmt.executeUpdate();
            System.out.println(rs+"修改成功");
        } catch (SQLException e) {
            
            e.printStackTrace();
        }
    }
	}

下面是按功能分解代码

  • 实现添加代码:
public static void main(String[] args) {
Book book = new Book();
		book.setId(4);
		book.setBookName("计算机英语");
		book.setPrice(20);
		book.setDescription("太难了");
		addBook(book);
		}
public static void addBook(Book book) {
		Connection conn = DBUtil.getConn();
        PreparedStatement pstmt;
        try {
        	if (conn ==null) {
				System.out.println("conn is null");
			}
            pstmt = conn.prepareStatement("insert into Book(id,bookName,price,description) values(?,?,?,?)");
            pstmt.setInt(1, book.getId());
            pstmt.setString(2, book.getBookName());
            pstmt.setInt(3, book.getPrice());
            pstmt.setString(4,book.getDescription());
            int rs = pstmt.executeUpdate();
            System.out.println(rs+"添加成功");
        } catch (SQLException e) {
            e.printStackTrace();
        }
	}

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  • 实现根据id来删除:
		deleteBookById(4);//删除id为4的信息
    public static void deleteBookById(int id){
    	Connection conn = DBUtil.getConn();
        PreparedStatement pstmt;
        try {
            pstmt = conn.prepareStatement("delete from Book where id=?");
            pstmt.setInt(1, id);
            int rs = pstmt.executeUpdate();
            System.out.println(rs+"删除成功");
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

在这里插入图片描述
在这里插入图片描述

  • 实现根据id查找
findBookById(1);//查找id为1的信息
public static Book findBookById(Integer id){
        Connection conn = DBUtil.getConn();
        PreparedStatement pstmt;
        Book book = new Book();
        try {
            pstmt = conn.prepareStatement("select * from Book where id = ?");
            pstmt.setInt(1, id);
            ResultSet rs = pstmt.executeQuery();
            while (rs.next()) {
            	book.setId(rs.getInt("id"));
            	book.setBookName(rs.getString("bookname"));
            	book.setPrice(rs.getInt("price"));
                book.setDescription(rs.getString("description"));
                System.out.println(book);
            }
        } catch (SQLException e) {  
            e.printStackTrace();
        }
        return book;
    }

在这里插入图片描述

  • 实现根据id修改信息
Book book1 = new Book();
		book1.setId(3);//修改id为3的信息
		book1.setBookName("H5");
		book1.setPrice(20);
		book1.setDescription("从入门到学Java");
		updateBook(book1);//修改
    public static void updateBook(Book book){
        Connection conn = DBUtil.getConn();
        PreparedStatement pstmt;
        try {
            pstmt = conn.prepareStatement("update Book set bookname=?,price=?,description=? where id=?");
            pstmt.setInt(4, book.getId());
            pstmt.setString(1, book.getBookName());
            pstmt.setInt(2, book.getPrice());
            pstmt.setString(3,book.getDescription());
            int rs = pstmt.executeUpdate();
            System.out.println(rs+"修改成功");
        } catch (SQLException e) { 
            e.printStackTrace();
        }
    }

在这里插入图片描述
在这里插入图片描述

以上就是我对MVC的理解和JDBC的基础操作,学习Java还需要继续努力.

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