一、jdbcTemplate的作用

• 它就是用于和数据库交互的，实现对表的crud。与dbutils相似

二、JdbcTemplate的使用

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.0.2.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.0.2.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>5.0.2.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.6</version>
        </dependency>

• 1.JdbcTemplate的最基本用法

package club.leyvan.jdbctemplate;

import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.datasource.DriverManagerDataSource;

/**
 * JdbcTemplate的最基本用法
 */
public class JdbcTemplateDemo1 {

    public static void main(String[] args) {
        //准备数据源：spring的内置数据源
        DriverManagerDataSource ds = new DriverManagerDataSource();
        ds.setDriverClassName("com.mysql.jdbc.Driver");
        ds.setUrl("jdbc:mysql://localhost:3306/test");
        ds.setUsername("root");
        ds.setPassword("123");

        //1.创建JdbcTemplate对象
        JdbcTemplate jt = new JdbcTemplate();
        //给jt设置数据源
        jt.setDataSource(ds);
        //2.执行操作
        jt.execute("insert into account(name,money)values('abc',1000)");
    }
}

• 2.JdbcTemplate基于Ioc的注入用法

xml的配置

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

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

    <!-- 配置数据源-->
    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"></property>
        <property name="url" value="jdbc:mysql://localhost:3306/test"></property>
        <property name="username" value="root"></property>
        <property name="password" value="1234"></property>
    </bean>
</beans>

配置后的java代码

package club.leyvan.jdbctemplate;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.jdbc.core.JdbcTemplate;

/**
 * JdbcTemplate的最基本用法
 */
public class JdbcTemplateDemo2 {

    public static void main(String[] args) {
        //1.获取容器
        ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
        //2.获取对象
        JdbcTemplate jt = ac.getBean("jdbcTemplate",JdbcTemplate.class);
        //3.执行操作
        jt.execute("insert into account(name,money)values('ddd',2222)");

    }
}

• JdbcTemplate的CRUD操作

package club.leyvan.jdbctemplate;

import com.itheima.domain.Account;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.RowMapper;

import java.sql.ResultSet;
import java.sql.SQLException;

/**
 * JdbcTemplate的CRUD操作
 */
public class JdbcTemplateDemo3 {

   public static void main(String[] args) {
        //1.获取容器
        ApplicationContext ac = new ClassPathXmlApplicationContext("bean.xml");
        //2.获取对象
        JdbcTemplate jt = ac.getBean("jdbcTemplate",JdbcTemplate.class);
        //3.执行操作
        //保存
//        jt.update("insert into account(name,money)values(?,?)","eee",3333f);
        //更新
//        jt.update("update account set name=?,money=? where id=?","test",4567,7);
        //删除
//        jt.update("delete from account where id=?",8);
        //查询所有
//        List<Account> accounts = jt.query("select * from account where money > ?",new AccountRowMapper(),1000f);
        //使用spring提供的封装策略
//        List<Account> accounts = jt.query("select * from account where money > ?",new BeanPropertyRowMapper<Account>(Account.class),1000f);
//        for(Account account : accounts){
//            System.out.println(account);
//        }
        //查询一个
//        List<Account> accounts = jt.query("select * from account where id = ?",new BeanPropertyRowMapper<Account>(Account.class),1);
//        System.out.println(accounts.isEmpty()?"没有内容":accounts.get(0));

        //查询返回一行一列（使用聚合函数，但不加group by子句）
        Long count = jt.queryForObject("select count(*) from account where money > ?",Long.class,1000f);
        System.out.println(count);


    }
}

/**
 * 定义Account的封装策略
 */
class AccountRowMapper implements RowMapper<Account>{
    /**
     * 把结果集中的数据封装到Account中，然后由spring把每个Account加到集合中
     * @param rs
     * @param rowNum
     * @return
     * @throws SQLException
     */
    @Override
    public Account mapRow(ResultSet rs, int rowNum) throws SQLException {
        Account account = new Account();
        account.setId(rs.getInt("id"));
        account.setName(rs.getString("name"));
        account.setMoney(rs.getFloat("money"));
        return account;
    }
}