JDBC简单增删改查实现(单表)

0.准备工作

开发工具: MySQL数据库, intelliJ IDEA2017.

准备jar包: mysql-connector-java-5.1.28-bin.jar(其他均可)

1. 数据库数据准备

2. 项目结构图示

3.代码

实体类Book.java

package com.zzuli.entity;

import java.util.Date;

/**
 *
 * 图书实体类
 * Created by hejjon on 2019/5/25.
 */
public class Book {
    private int id;
    private String bookName;
    private String author;
    private Date pubDate;           // 出版日期 util.Date

    public Book() {
    }

    public Book(int id, String bookName, String author, Date pubDate) {
        this.id = id;
        this.bookName = bookName;
        this.author = author;
        this.pubDate = pubDate;
    }

    public Book(String bookName, String author, Date pubDate) {
        this.bookName = bookName;
        this.author = author;
        this.pubDate = pubDate;
    }

    public int getId() {
        return id;
    }

    public String getBookName() {
        return bookName;
    }

    public String getAuthor() {
        return author;
    }

    public Date getPubDate() {
        return pubDate;
    }

    public void setId(int id) {
        this.id = id;
    }

    public void setBookName(String bookName) {
        this.bookName = bookName;
    }

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

    public void setPubDate(Date pubDate) {
        this.pubDate = pubDate;
    }

    @Override
    public String toString() {
        return "Book{" +
                "id=" + id +
                ", bookName='" + bookName + '\'' +
                ", author='" + author + '\'' +
                ", pubDate=" + pubDate +
                '}';
    }
}

Dao层接口 BookDao.java

package com.zzuli.dao;

import com.zzuli.entity.Book;

import java.util.List;

/**
 * Created by hejjon on 2019/5/25.
 */
public interface BookDao {

    /**
     * 增添图书
     * @param book  要添加的book对象
     * @return
     */
    int insertBook(Book book);

    /**
     * 删除指定id的图书
     * @param id    要删除的图书的id
     * @return
     */
    int deleteBook(int id);

    /**
     * 修改图书
     * @param book  修改后的图书
     * @return
     */
    int updateBook(Book book);

    /**
     * 查找指定书名的图书
     * @param bookName
     * @return
     */
    Book selectBookByName(String bookName);

    List<Book> selectAllBook();
}

Dao层实现类: BookDaoImpl.java

package com.zzuli.dao.impl;

import com.zzuli.dao.BookDao;
import com.zzuli.entity.Book;

import java.sql.*;
import java.util.ArrayList;
import java.util.List;

/**
 * Created by hejjon on 2019/5/25.
 */
public class BookDaoImpl implements BookDao {

    private final String jdbcDriver = "com.mysql.jdbc.Driver";
    private final String url = "jdbc:mysql://localhost:3306/db_book";
    private final String userName = "root";
    private final String password  = "123123";

    @Override
    public int insertBook(Book book) {
        int n = 0;
        String sql = "insert into t_book values (default,?,?,?)";
        Connection conn = null;
        PreparedStatement ps = null;
        java.sql.Date pubDate = null;
        try {
            // 加载驱动
            Class.forName(jdbcDriver);
            // 获取连接
            conn = DriverManager.getConnection(url, userName, password);
            // 创建会话
            ps = conn.prepareStatement(sql);
            // 设置 ? 的值
            ps.setString(1, book.getBookName());
            ps.setString(2, book.getAuthor());
            pubDate = new java.sql.Date(book.getPubDate().getTime());
            ps.setDate(3, pubDate);
            // 执行sql
            n = ps.executeUpdate();

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {     // 关闭数据库资源
            try {
                if (null != ps) {
                    ps.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
            try {
                if (null != conn) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return n;
    }

    @Override
    public int deleteBook(int id) {
        String sql = "delete from t_book where id=?";
        int n = 0;
        Connection conn = null;
        PreparedStatement ps = null;

        try {
            // 加载驱动
            Class.forName(jdbcDriver);
            // 获取连接
            conn = DriverManager.getConnection(url, userName, password);
            // 创建会话
            ps = conn.prepareStatement(sql);
            // 设置 ? 的值
            ps.setInt(1, id);
            // 执行sql
            n =  ps.executeUpdate();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (null != ps) {
                    ps.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
            try {
                if (null != conn) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

        return n;
    }

    @Override
    public int updateBook(Book book) {
        String sql = "update t_book set bookName=?, author=?, pubDate=? where id=?";
        int n = 0;
        Connection conn =  null;
        PreparedStatement ps = null;
        try {
            // 加载驱动
            Class.forName(jdbcDriver);
            // 获取连接
            conn = DriverManager.getConnection(url, userName, password);
            // 创建会话
            ps = conn.prepareStatement(sql);
            ps.setString(1, book.getBookName());
            ps.setString(2, book.getAuthor());
            ps.setDate(3, new java.sql.Date(book.getPubDate().getTime()));
            ps.setInt(4, book.getId());
            n = ps.executeUpdate();

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (null != ps) {
                    ps.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
            try {
                if (null != conn) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return n;
    }

    @Override
    public Book selectBookByName(String bookName) {
        String sql = "select * from t_book where bookName=?";
        Book book = null;
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;
        try {
            // 加载驱动
            Class.forName(jdbcDriver);
            // 获取连接
            conn = DriverManager.getConnection(url, userName, password);
            // 创建会话
            ps = conn.prepareStatement(sql);
            ps.setString(1, bookName);
            rs = ps.executeQuery();

            if (rs.next()) {
                int id = rs.getInt("id");
                String name = rs.getString("bookName");
                String author = rs.getString("author");
                java.util.Date pubDate = rs.getDate("pubDate");
                book = new Book(id, name, author, pubDate);
            }

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (null != ps) {
                    ps.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
            try {
                if (null != conn) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        return book;
    }

    @Override
    public List<Book> selectAllBook() {
        String sql = "select * from t_book";
        List<Book> list = new ArrayList<>();
        Connection conn = null;
        PreparedStatement ps = null;
        ResultSet rs = null;

        try {
            // 加载驱动
            Class.forName(jdbcDriver);
            // 获取连接
            conn = DriverManager.getConnection(url, userName, password);
            // 创建会话
            ps = conn.prepareStatement(sql);
            // 获取结果集
            rs = ps.executeQuery();
            // 遍历结果集
            while (rs.next()) {
                int id = rs.getInt("id");
                String bookName = rs.getString("bookName");
                String author = rs.getString("author");
                Date pubDate = rs.getDate("pubDate");

                Book book = new Book(id, bookName, author, pubDate);
                list.add(book);
            }

        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (null != ps) {
                    ps.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
            try {
                if (null != conn) {
                    conn.close();
                }
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }

        return list;
    }
}

测试类:Test.java

package com.zzuli.test;

import com.zzuli.dao.BookDao;
import com.zzuli.dao.impl.BookDaoImpl;
import com.zzuli.entity.Book;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;

/**
 * 测试类
 * Created by hejjon on 2019/5/25.
 */
public class Test {
    public static void main(String[] args) {
        // testInsert();
        //  testDelete();
        // sestUpdate();
        // testSelect();

        testSelectAllBook();

    }

    private static void testSelectAllBook() {
        BookDao bookDao = new BookDaoImpl();

        List<Book> list = new ArrayList<>();

        list = bookDao.selectAllBook();

        for (Book book : list) {
            System.out.println(book);
        }
    }

    // 测试按书名查找图书
    public static void testSelect() {
        BookDao bookDao = new BookDaoImpl();
        Book book = bookDao.selectBookByName("西游记");

        System.out.println(book);
    }

    // 测试修改图书方法
    public static void testUpdate() {
        // 创建dao层实现类对象
        BookDao bookDao = new BookDaoImpl();
        String dateStr = "1788-06-15";
        Date pubDate = null;
        DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
        try {
            pubDate = df.parse(dateStr);
        } catch (ParseException e) {
            e.printStackTrace();
        }

        Book book = new Book(2, "西游记", "吴承恩", pubDate);

        int i = bookDao.updateBook(book);

        if (i > 0) {
            System.out.println("图书修改成功");
        } else {
            System.out.println("图书修改失败");
        }
    }

    // 测试删除图书方法
    public static void testDelete() {
        BookDao bookDao = new BookDaoImpl();
        int i = bookDao.deleteBook(5);

        if (i > 0) {
            System.out.println("删除图书成功");
        } else {
            System.out.println("删除图书失败");
        }
    }

    // 测试添加图书方法
    public static void testInsert() {
        // 创建dao层实现类对象
        BookDao bookDao = new BookDaoImpl();
        String dateStr = "1678-09-24";
        Date pubDate = null;
        DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
        try {
            pubDate = df.parse(dateStr);
        } catch (ParseException e) {
            e.printStackTrace();
        }

        Book book = new Book("鹿鼎记", "张三", pubDate);

        int i = bookDao.insertBook(book);

        if (i > 0) {
            System.out.println("图书添加成功");
        } else {
            System.out.println("图书添加失败");
        }
    }
}

4.总结:

java.sql.Date, java.util.Date, String 之间的相互转换:

// String ---> java.util.Date       parse()方法
String DateStr = "1997-02-24";
Date date = null;
DateFormat df = new SimpleDateFormat("yyyy-MM-dd");
try {
    date = df.parse(DateStr);
} catch (ParseException e) {
    e.printStackTrace();
}

// java.util.Date ---> String       format()方法
System.out.println(df.format(date));        // 1997-02-24

System.out.println(System.currentTimeMillis());     // 1558864421743

// java.util.Date ---> java.sql.Date
java.util.Date utilDate = new java.util.Date(1558864204513L);      // 是long类型 L别丢了

java.sql.Date sqlDate = new java.sql.Date(utilDate.getTime());
System.out.println(utilDate);        // Sun May 26 17:50:04 CST 2019
System.out.println(sqlDate);    // 2019-05-26