Spring中的JdbcTemplate

JdbcTemplate的基本用法：

一个简单的示例：
pom.xml

<packaging>jar</packaging>
    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.1.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-jdbc</artifactId>
            <version>5.2.1.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>5.2.1.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.38</version>
        </dependency>
    </dependencies>

JdbcTemplateDemo01:

package net.togogo.jdbcTemplate;

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

/**
 * JdbcTemplate的最基本用法
 */
public class JdbcTemplateDemo01 {
    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/eesy");
        ds.setUsername("root");
        ds.setPassword("123456");

        //1.创建JdbcTemplate对象
        JdbcTemplate jdbcTemplate = new JdbcTemplate();
        //给jdbcTemplate设置数据源
        jdbcTemplate.setDataSource(ds);
        //2.执行操作
        jdbcTemplate.execute("insert into account1(username,money)values('ccc',1000)");
    }
}

Spring基本xml的JdbcTemplate

bean.xml

<?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/eesy"></property>
        <property name="username" value="root"></property>
        <property name="password" value="123456"></property>
    </bean>
</beans>

JdbcTemplateDemo02:

package net.togogo.jdbcTemplate;

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

/**
 * JdbcTemplate的最基本用法
 */
public class JdbcTemplateDemo02 {
    public static void main(String[] args) {

        //1.获取容器
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("bean.xml");
        //2.获取对象
        JdbcTemplate jdbcTemplate = applicationContext.getBean("jdbcTemplate",JdbcTemplate.class);
        //3.执行操作
        jdbcTemplate.execute("insert into account1(username,money)values('ddd',1000)");
    }
}

JdbcTemplate的CRUD操作

package net.togogo.jdbcTemplate;

import net.togogo.bean.Account;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

import java.util.List;

/**
 * JdbcTemplate的CRUD操作
 */
public class JdbcTemplateDemo03 {
    public static void main(String[] args) {

        //1.获取容器
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext("bean.xml");
        //2.获取对象
        JdbcTemplate jdbcTemplate = applicationContext.getBean("jdbcTemplate",JdbcTemplate.class);
        //3.执行操作
        //保存
//        jdbcTemplate.update("insert into account1(username,money)values(?,?)","eee",1000f);

        //更新
//        jdbcTemplate.update("update account1 set username=?,money=? where id=?","test",1234f,5);

        //删除
//        jdbcTemplate.update("delete from account1 where id=?",5);

        //查询所有
//        List<Account> accountList = jdbcTemplate.query("select * from account1 where money > ?", new BeanPropertyRowMapper<Account>(Account.class),1000f);
//        for (Account account : accountList) {
//            System.out.println(account);
//        }
        //查询一个
//        List<Account> accountList = jdbcTemplate.query("select * from account1 where id = ?", new BeanPropertyRowMapper<Account>(Account.class), 1);
//        for (Account account : accountList) {
//            System.out.println(account);
//        }

        //查询返回一行一列（使用聚合函数，但不包括group by语句）
        Integer integer = jdbcTemplate.queryForObject("select count(*) from account1 where money > ?", Integer.class, 1000f);
        System.out.println(integer);

    }
}

实际开发中我们写在dao层是实现类中：

package net.togogo.dao.impl;

import net.togogo.bean.Account;
import net.togogo.dao.IAccountDao;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;

import java.util.List;

/**
 * 账户的持久层实现类
 */
public class AccountDaoImpl implements IAccountDao {

    private JdbcTemplate jdbcTemplate;

    public void setJdbcTemplate(JdbcTemplate jdbcTemplate) {
        this.jdbcTemplate = jdbcTemplate;
    }

    public Account findAccountById(Integer id) {
        List<Account> accountList = jdbcTemplate.query("select * from account1 where id = ?", new BeanPropertyRowMapper<Account>(Account.class), id);
        return accountList.isEmpty()?null:accountList.get(0);
    }

    public Account findAccountByName(String name) {
        List<Account> accountList = jdbcTemplate.query("select * from account1 where username = ?", new BeanPropertyRowMapper<Account>(Account.class), name);
        if(accountList.isEmpty()){
            return null;
        }
        if(accountList.size()>1){
            throw  new RuntimeException("结果集不唯一");
        }
        return accountList.get(0);
    }

    public void updateAccount(Account account) {
        jdbcTemplate.update("update account1 set username=?,money=? where id=?",account.getUserName(),account.getMoney(),account.getId());
    }
}

假如项目中有许多dao层实现类，他们都需要一个JdbcTemplate对象，那么这些dao层实现类的代码会有许多重复，而这时候这些dao层实现类可以继承JdbcDaoSupport类来减少重复代码。
不过该方法只适用于xml配置。

package net.togogo.dao.impl;

import net.togogo.bean.Account;
import net.togogo.dao.IAccountDao;
import org.springframework.jdbc.core.BeanPropertyRowMapper;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.jdbc.core.support.JdbcDaoSupport;

import java.util.List;

/**
 * 账户的持久层实现类
 */
public class AccountDaoImpl2 extends JdbcDaoSupport implements IAccountDao {

    public Account findAccountById(Integer id) {
        List<Account> accountList = super.getJdbcTemplate().query("select * from account1 where id = ?", new BeanPropertyRowMapper<Account>(Account.class), id);
        return accountList.isEmpty()?null:accountList.get(0);
    }

    public Account findAccountByName(String name) {
        List<Account> accountList = super.getJdbcTemplate().query("select * from account1 where username = ?", new BeanPropertyRowMapper<Account>(Account.class), name);
        if(accountList.isEmpty()){
            return null;
        }
        if(accountList.size()>1){
            throw  new RuntimeException("结果集不唯一");
        }
        return accountList.get(0);
    }

    public void updateAccount(Account account) {
        super.getJdbcTemplate().update("update account1 set username=?,money=? where id=?",account.getUserName(),account.getMoney(),account.getId());
    }
}