Spring 用法学习总结（四）之 JdbcTemplate 连接数据库

🐉目录

9 JdbcTemplate

Spring 框架对 JDBC 进行了封装，使用 JdbcTemplate 方便实现对数据库操作

相关包：

百度网盘链接

https://pan.baidu.com/s/1Gw1l6VKc-p4gdqDyD626cg?pwd=6666

创建properties配置文件

💥注意：高版本 MySQL 需要将 useSSL 设置为 false

此外，还需将驱动器修改为适合 MySQL 的版本: mysql-connector-java各种版本下载链接https://mvnrepository.com/artifact/mysql/mysql-connector-java

如果仍报错则将 com.mysql.jdbc.Driver 改为 com.mysql.cj.jdbc.Driver

url=jdbc:mysql://localhost:3306/study?useSSL=false&useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC
name=root
password=123456
driverClassName=com.mysql.cj.jdbc.Driver

study 数据库中的 book 表

导入语法：source sql 文件地址，无法插入中文，请修改数据库编码为 utf-8

create table book(
bookid int(10) primary key auto_increment,
bookname varchar(50),
booksale double(7,2));

insert into book(bookname,booksale) values
('Spring揭秘',75.5),
('Spring实战',56),
('Spring源码深入解析',72);

创建 xml 文件

com.alibaba.druid.pool.DruidDataSource 用来配置连接池

org.springframework.jdbc.core.JdbcTemplate 用来连接数据库

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context.xsd
       http://www.springframework.org/schema/aop
       http://www.springframework.org/schema/aop/spring-aop.xsd
       http://www.springframework.org/schema/tx
       http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">

    <!--加载配置文件-->
    <context:property-placeholder location="classpath:user.properties" file-encoding="UTF-8"/>
    <!-- 数据库连接池 -->
    <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource"
          destroy-method="close">
        <property name="url" value="${url}" />
        <property name="username" value="${name}" />
        <property name="password" value="${password}" />
        <property name="driverClassName" value="${driverClassName}" />
    </bean>

    <!-- JdbcTemplate 对象 -->
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <!--注入 dataSource-->
        <property name="dataSource" ref="dataSource"></property>
    </bean>

    <!-- 组件扫描 -->
    <context:component-scan base-package="springstudy4"></context:component-scan>
</beans>

Book 类存储书籍信息

Dao 是数据库操作，其中 BookDao 为接口并且声明了对数据库操作的方法，BookDaoIml 类实现了 BookDao 接口

Service 是业务操作，可以调用 BookDao 接口中的方法

Test 类进行测试，通过 Service 类调用 BookDao 接口中的方法

创建 BookDao 接口

package springstudy4;

import java.util.List;

public interface BookDao {
    //增
    void add(Book book);

    //批量添加
    void batchAddBook(List<Object[]> batchArgs);

    //删
    void delete(int id);


    //批量删除
    void batchDeleteBook(List<Object[]> batchArgs);

    //改
    void update(Book book);

    //批量修改
    void batchUpdateBook(List<Object[]> batchArgs);

    //查
    int selectCount();

    //查询返回对象
    Book findBookInfo(int id);

    //查询返回集合
    List<Book> findAllBook();
}

创建 BookService 类

package springstudy4;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class BookService {
    //注入 dao
    @Autowired
    private BookDao bookDao;

    //添加
    public void addBook(Book book) {
        bookDao.add(book);
    }

    //批量添加
    public void batchAdd(List<Object[]> batchArgs) {
        bookDao.batchAddBook(batchArgs);
    }

    //删除
    public void deleteBook(int id) {
        bookDao.delete(id);
    }

    //批量删除
    public void batchDelete(List<Object[]> batchArgs) {
        bookDao.batchDeleteBook(batchArgs);
    }

    //修改
    public void updateBook(Book book) {
        bookDao.update(book);
    }

    //批量添加
    public void batchUpdate(List<Object[]> batchArgs) {
        bookDao.batchUpdateBook(batchArgs);
    }

    //查找
    public void findBook(int id) {
        bookDao.findBookInfo(id);
    }

    //查找全部
    public List<Book> findAll() {
        return bookDao.findAllBook();
    }
}

创建 Book 类

package springstudy4;

public class Book {
    private int bookid;
    private String bookname;
    private double booksale;

    public int getBookid() {
        return bookid;
    }

    public void setBookid(int bookid) {
        this.bookid = bookid;
    }

    public String getBookname() {
        return bookname;
    }

    public void setBookname(String bookname) {
        this.bookname = bookname;
    }

    public double getBooksale() {
        return booksale;
    }

    public void setBooksale(double booksale) {
        this.booksale = booksale;
    }

    @Override
    public String toString() {
        return "Book{" +
                "bookid=" + bookid +
                ", bookname='" + bookname + '\'' +
                ", booksale=" + booksale +
                '}';
    }
}

👀创建 BookDaoIml 类（重点）👀

BookDaoIml 类定义了 CRUD 方法，通过 JdbcTemplate 模块可以对数据库中的一条或多条数据进行操作

package springstudy4;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Repository;

import java.util.Arrays;
import java.util.List;

@Repository
public class BookDaoImpl implements BookDao {
    //注入 JdbcTemplate
    @Autowired
    private JdbcTemplate jdbcTemplate;

    //增
    @Override
    public void add(Book book) {
        String sql = "insert into book values(?,?,?)";
        jdbcTemplate.update(sql, book.getBookid(), book.getBookname(), book.getBooksale());
    }

    //批量添加
    @Override
    public void batchAddBook(List<Object[]> batchArgs) {
        String sql = "insert into book values(?,?,?)";
        int[] ints = jdbcTemplate.batchUpdate(sql, batchArgs);
        System.out.println(Arrays.toString(ints));
    }

    //删
    @Override
    public void delete(int id) {
        String sql = "delete from book where bookid=?";
        int update = jdbcTemplate.update(sql, id);
        System.out.println(update);
    }

    //批量删除
    @Override
    public void batchDeleteBook(List<Object[]> batchArgs) {
        String sql = "delete from book where bookid=?";
        int[] ints = jdbcTemplate.batchUpdate(sql, batchArgs);
        System.out.println(Arrays.toString(ints));
    }

    //改
    @Override
    public void update(Book book) {
        String sql = "update book set bookname=?,booksale=? where bookid=?";
        Object[] args = {book.getBookname(), book.getBooksale(),book.getBookid()};
        int update = jdbcTemplate.update(sql, args);
        System.out.println(update);
    }

    //批量修改
    @Override
    public void batchUpdateBook(List<Object[]> batchArgs) {
        String sql = "update book set bookname=?,booksale=? where bookid=?";
        int[] ints = jdbcTemplate.batchUpdate(sql, batchArgs);
        System.out.println(Arrays.toString(ints));
    }

    //查
    @Override
    public int selectCount() {
        String sql = "select count(*) from book";
        Integer count = jdbcTemplate.queryForObject(sql, Integer.class);
        return count;
    }

    //查询返回对象
    @Override
    public Book findBookInfo(int id) {
        String sql = "select * from book where bookid=?";
        //调用方法
        Book book = jdbcTemplate.queryForObject(sql, new
                BeanPropertyRowMapper<Book>(Book.class), id);
        return book;
    }

    //查询返回集合
    @Override
    public List<Book> findAllBook() {
        String sql = "select * from book";
        //调用方法
        List<Book> bookList = jdbcTemplate.query(sql, new
                BeanPropertyRowMapper<Book>(Book.class));
        return bookList;
    }
}

创建 Test 类

package springstudy4;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import java.util.ArrayList;
import java.util.List;

public class Test {
    public static void main(String[] args) {
        ApplicationContext context =
                new ClassPathXmlApplicationContext("bean4.xml");
        BookService bookService = context.getBean("bookService", BookService.class);

        Book book = new Book();
        List<Book> bookList;
        List<Object[]> batchArgs = new ArrayList<>();
        //查找所有
        bookList = bookService.findAll();
        for(Book i : bookList) {
            System.out.println(i);
        }
//        //增加一条
//        book.setBookid(5);
//        book.setBookname("算法导论");
//        book.setBooksale(65);
//        bookService.addBook(book);
//        //批量添加测试
//        batchArgs.clear();
//        Object[] a1 = {6,"java",26};
//        Object[] a2 = {7,"c++", 66};
//        Object[] a3 = {8,"MySQL",62};
//        batchArgs.add(a1);
//        batchArgs.add(a2);
//        batchArgs.add(a3);
//        //调用批量添加
//        bookService.batchAdd(batchArgs);

        //批量删除
        batchArgs.clear();
        Object[] b1 = {6};
        Object[] b2 = {7};
        batchArgs.add(b1);
        batchArgs.add(b2);
        //调用方法实现批量删除
        bookService.batchDelete(batchArgs);

        //批量修改
        batchArgs.clear();
        Object[] c1 = {"java", 66.5, 6};
        Object[] c2 = {"c++", 77.0, 7};
        Object[] c3 = {"MySQL",88.5, 8};
        batchArgs.add(c1);
        batchArgs.add(c2);
        batchArgs.add(c3);
        //调用方法实现批量修改
        bookService.batchUpdate(batchArgs);
    }
}